DESC:PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.
CROSS REFERENCE
This Application is based upon and derives the benefit of Indian Provisional Application Number 202441062236 filed on August 16, 2024, the contents of which are incorporated herein by reference.
TECHNICAL FIELD
[0001] Embodiments of the present disclosure generally relate to air-breathing engines in supersonic or hypersonic aircrafts. In particular, the present disclosure relates to a Curved Compression Ramp (CCR) air intake apparatus for ramjet and scramjet engines and method thereof.
BACKGROUND
[0002] Generally, ramjets or scramjets, are advanced airbreathing engines designed to operate efficiently at supersonic or hypersonic speeds, typically exceeding speed of sound. The ramjet engine is a form of airbreathing jet engine that requires forward motion of the engine to provide air for combustion. Further, ramjet engines work most efficiently at supersonic speeds around for example, Mach 3 (3,700 km/h). Further, the scramjet engine is a variant of the ramjet airbreathing jet engine in which flow is supersonic inside the combustor.
[0003] A vehicle is said to be travelling at hypersonic velocities when the vehicle exceeds Mach 5 or close to 1.8 km/s. In air-breathing engines, the air is captured, compressed, and passes through the combustor for heat addition and the high energy flow is expanded to generate thrust. In other words, the ramjet or scramjet engine are air-breathing engines that are the ideal propulsion system for vehicles flying at supersonic or hypersonic speeds (M>1). Scramjets are integral to next-generation high-speed aerospace vehicles due to capability of the scramjets, to sustain atmospheric flight at these extreme velocities.
[0004] FIG. 1 illustrates a schematic diagram representation of a scramjet engine 100. As illustrated in FIG. 1, a conventional scramjet engine 100 is composed of four primary components such as an air intake 101, an isolator 103, a combustor 105, and a nozzle 107. The air intake 101 may be configured to decelerate and compress an incoming high-speed airflow 109. The air intake needs to ensure that the airflow 109 entering the combustor 105 is steady and parallel, maintaining a stable supersonic flow with a sufficient mass flow rate to achieve a started condition. For optimal operation, the air intake 101 must also exhibit high thermodynamic efficiency, robustness against back-pressure fluctuations, and minimal structural weight and drag. Further, the isolator 103, positioned downstream of the air intake 101, further decelerates the compressed flow, and prevents disturbances from propagating upstream towards the air intake 101. Furthermore, the combustor 105 then adds thermal energy to the airflow, while the nozzle 107 accelerates this high-enthalpy flow to produce thrust. Moreover, effective performance of the scramjet engine depends on the air intake 101 and the isolator 103, providing a well-conditioned flow to the combustor 105.
[0005] Also, high-speed air intakes are evaluated based on compression capability (pressure ratio) and efficiency (pressure recovery) of the air intakes. FIG. 2 illustrates various two-dimensional (2D) rectangular intake configurations of the scramjet engine 100. A flat or planar simple ramp intake 201 (as shown in FIG. 2) can achieve high pressure ratios, however, the flat or planar simple ramp intake 201, a two-step ramp intake 203, and a multi-step ramp intake 205 are prone to significant stagnation pressure losses. In contrast, isentropic intakes, such as Prandtl-Meyer intake 207 and/or Busemann designs (not shown in FIG. 2), utilize compression waves to improve pressure recovery. However, these designs require extensive external compression surfaces, which increase structural weight and aero-thermal loads, making them less practical. However, designing high-speed air intakes, particularly for hypersonic applications, presents several challenges, including managing boundary layer separation on compression surfaces, mitigating adverse shock-boundary layer interactions at expansion corners, and addressing thrust losses due to intake un-start conditions.
[0006] Therefore, there is a need in the art for improved apparatus and methods to address at least the aforementioned technical problems in the prior arts, by providing a Curved Compression Ramp (CCR) air intake apparatus for high-speed air breathing engines and method thereof.

SUMMARY
[0007] This summary is provided to introduce a selection of concepts, in a simple manner, which is further described in the detailed description of the disclosure. This summary is neither intended to identify key or essential inventive concepts of the subject matter nor to determine the scope of the disclosure.
[0008] An aspect of the present disclosure provides a Curved Compression Ramp (CCR) air intake apparatus for ramjet and scramjet engines. The CCR air intake apparatus comprises a Curved Compression Ramp (CCR) assembly configured to perform flow shaping of incoming high-speed airflow. The curved compression ramp assembly further comprises a fore segment with a curved surface configured to induce a curved shock wave through an interaction of an oblique ramp shock wave and a continuous series of isentropic compression waves. In an embodiment, the curved surface may generate a series of compression waves that progressively and isentropically compress the airflow. Further, the curved compression ramp assembly comprises a planar aft segment downstream of the curved surface configured to manage and stabilize the airflow. In an embodiment, the planar aft segment may be tangentially aligned with an end of the curved surface and inclined at a pre-defined angle to manage and stabilize a compressed airflow. Further, the curved compression ramp assembly comprises a leading edge of the curved compression ramp assembly positioned to generate a small flow deflection angle of the incoming high-speed airflow, and generate the oblique ramp shock wave transitioning into a curved shock wave profile due to interaction with the isentropic compression waves along the curved surface in the fore segment surface. Further, the CCR air intake apparatus comprises a curved cowl assembly positioned opposite to the curved compression ramp assembly. The curved cowl assembly comprises a cowl lip on the curved cowl assembly positioned downstream to the leading edge of the curved compression ramp assembly, to satisfy a shock-on-lip condition at a pre-determined location on the cowl lip. In an embodiment, the cowl lip may be positioned relative to the leading edge of the curved compression ramp assembly, based on at least one design configuration. Furthermore, the curved cowl assembly comprises a concavely curved inner surface with the at least one design configuration and aligned with the curved compression ramp assembly to direct airflow into an isolator section with at least parallel walls and non-parallel walls downstream to the curved cowl assembly.
[0009] Another aspect of the present disclosure includes a method for managing high-speed airflow in a Curved Compression Ramp (CCR) air intake apparatus for ramjet and scramjet engines. The method includes performing, by a Curved Compression Ramp (CCR) air intake apparatus, a flow shaping incoming high-speed airflow using a Curved Compression Ramp (CCR) assembly. In an embodiment, the flow shaping comprises generating, by the CCR air intake apparatus, an initial oblique ramp shock wave at a leading edge of the CCR assembly by generating a small flow deflection angle in the incoming airflow. Further, the flow shaping comprises inducing, by the CCR air intake apparatus, a curved shock wave through an interaction of the oblique ramp shock wave with a series of isentropic compression waves along a curved fore segment of the CCR assembly. Furthermore, the flow shaping comprises stabilizing and managing, by the CCR air intake apparatus, the compressed airflow in a planar aft segment tangentially aligned with an end of the curved fore segment, wherein the planar aft segment is inclined at a pre-defined angle. The method then includes directing, by the CCR air intake apparatus, the compressed airflow into an isolator section with at least one of parallel walls and non-parallel walls downstream to a curved cowl assembly being positioned opposite to the CCR assembly. In an embodiment, directing the compressed airflow comprises aligning, by the CCR air intake apparatus, a leading-edge portion of an isolator top-plate comprising a concavely curved inner surface of the curved cowl assembly to guide the airflow into the isolator section. Subsequently, directing the airflow comprises configuring, by the CCR air intake apparatus, a cowl lip of the curved cowl assembly to satisfy a shock-on-lip condition at a pre-defined location relative to the leading edge of the CCR assembly. In an embodiment, the cowl lip may be positioned relative to the leading edge of the curved compression ramp assembly, based on at least one design configuration. Furthermore, in an embodiment, the cowl lip location may be optimized for intake stability and capture efficiency under both design and off-design conditions.
[0010] To further clarify the advantages and features of the present disclosure, a more particular description of the disclosure will follow by reference to specific embodiments thereof, which are illustrated in the appended figures. It is to be appreciated that these figures depict only typical embodiments of the disclosure and are therefore not to be considered limiting in scope. The disclosure will be described and explained with additional specificity and detail with the appended figures.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
[0011] The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and, together with the description, serve to explain the disclosed principles. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system and/or methods in accordance with embodiments of the present subject matter are now described, by way of example only, and with reference to the accompanying figures, in which:
[0012] FIG. 1 illustrates a schematic diagram representation of a scramjet engine;
[0013] FIG. 2 illustrates schematic diagram representations of a plurality of types of rectangular Two-Dimensional (2D) intake configurations of scramjet engines such as those shown in FIG. 1;
[0014] FIG. 3 illustrates a schematic representation of a Curved Compression Ramp (CCR) air intake apparatus for ramjet engine and scramjet engine, in accordance with an embodiment of the present disclosure;
[0015] FIG. 4 illustrates a schematic diagram representation of a supersonic or hypersonic flow past a curved compression wedge at zero-angle-of-attack, in accordance with an embodiment of the present disclosure;
[0016] FIG. 5 illustrates a side view of a schematic diagram representation of an exemplary model of Curved Compression Ramp (CCR) assembly, in accordance with an embodiment of the present disclosure;
[0017] FIG. 6 illustrates a schematic diagram representation of an exemplary CCR air intake apparatus including a provision for isolator back pressure variation, in accordance with an embodiment of the present disclosure;
[0018] FIG. 7 illustrates a side view of a schematic diagram representation of an exemplary Curved Compression Ramp (CCR) air intake apparatus strut-mounted in a test-section of a wind tunnel for isolator back pressure variation studies, in accordance with an embodiment of the present disclosure;
[0019] FIG. 8 illustrates schematic diagram representations of different states of intake operation and flow features of the CCR air intake apparatus based on variation in isolator back pressure, in accordance with an embodiment of the present disclosure;
[0020] FIG. 9 illustrates a graph diagram representation of a variation in isolator back pressure ratio and throttling ratio as a function of time, in accordance with an embodiment of the present disclosure;
[0021] FIG. 10 illustrates a schematic diagram representation of the CCR air intake apparatus used for angle-of-attack variation studies, in accordance with an embodiment of the present disclosure;
[0022] FIG. 11 illustrates schematic diagram representations of different states of intake operation and flow features of the CCR air intake apparatus based on variation in angle of attack, in accordance with an embodiment of the present disclosure; and
[0023] FIG. 12 illustrates a flow chart representation of a method for managing high-speed airflow in a Curved Compression Ramp (CCR) air intake apparatus for ramjet and scramjet engines, in accordance with an embodiment of the present disclosure.
[0024] Further, those skilled in the art will appreciate that elements in the figures are illustrated for simplicity and may not have necessarily been drawn to scale. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the figures by conventional symbols, and the figures may show only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the figures with details that will be readily apparent to those skilled in the art having the benefit of the description herein.
DETAILED DESCRIPTION
[0025] For simplicity and illustrative purposes, the present disclosure is described by referring mainly to examples thereof. The examples of the present disclosure described herein may be used together in different combinations. In the following description, details are set forth in order to provide an understanding of the present disclosure. It will be readily apparent, however, that the present disclosure may be practiced without limitation to all these details. Also, throughout the present disclosure, the terms “a” and “an” are intended to denote at least one of a particular element. The terms “a” and “an” may also denote more than one of a particular element. In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings. The singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise.
[0026] As used herein, the term “includes” means includes but not limited to, the term “including” means including but not limited to. The term “based on” means based at least in part on, the term “based upon” means based at least in part upon, and the term “such as” means such as but not limited to. The term “relevant” means closely connected or appropriate to what is being performed or considered.
[0027] For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Such alterations and further modifications in the illustrated system, and such further applications of the principles of the disclosure as would normally occur to those skilled in the art are to be construed as being within the scope of the present disclosure. It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the disclosure and are not intended to be restrictive thereof.
[0028] In the present document, the word “exemplary” is used herein to mean “serving as an example, instance, or illustration”. Any embodiment or implementation of the present subject matter described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.
[0029] While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however that it is not intended to limit the disclosure to the forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.
[0030] The terms “comprise”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that one or more devices or sub-systems or elements or structures or components preceded by “comprises… a” does not, without more constraints, preclude the existence of other devices, sub-systems, additional sub-modules. Appearances of the phrase “in an embodiment”, “in another embodiment”, “in an exemplary embodiment” and similar language throughout this specification may, but not necessarily do, all refer to the same embodiment.
[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure belongs. The system, methods, and examples provided herein are only illustrative and not intended to be limiting.
[0032] A description of an embodiment with several components in communication with each other does not imply that all such components are required. On the contrary, a variety of optional components are described to illustrate the wide variety of possible embodiments of the invention. In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.
[0033] In the present disclosure, terms such as “upper”, “lower”, “left”, “right”, “front”, “rear”, “vertical”, “horizontal”, “side”, “bottom”, “opposite”, “down”, “relative” and the like, may refer to an orientation or a positional relationship based on that shown in the drawings, and are merely relational terms, which are used for convenience in describing structural relationships of various components or elements of the present invention, and do not denote any one of the components or elements of the present disclosure, and are not to be construed as limiting the present invention.
[0034] In the present disclosure, terms such as “attached”, “coupled”, “connected”, “positioned”, and the like are to be construed broadly and refer to either a fixed connection, or a movable, or an integral or removable connection; can be directly connected or indirectly connected through an intermediate medium. The specific meaning of the terms in the present disclosure can be determined according to circumstances by a person skilled in the relevant art or the art and is not to be construed as limiting the present disclosure.
[0035] Embodiments described herein provide a Curved Compression Ramp (CCR) air intake apparatus and method for managing high-speed airflow in a Curved Compression Ramp (CCR) air intake apparatus for ramjet and scramjet engines. The CCR air intake apparatus includes a Curved Compression Ramp (CCR) assembly configured to perform flow shaping of incoming high-speed airflow. The curved compression ramp assembly further includes a fore segment with a curved surface configured to induce a curved shock wave through an interaction of an oblique ramp shock wave and a continuous series of isentropic compression waves. In an embodiment, the curved surface may generate a series of compression waves that progressively and isentropically compress the airflow. Further, the curved compression ramp assembly includes a planar aft segment downstream of the curved surface configured to manage and stabilize the airflow. In an embodiment, the planar aft segment may be tangentially aligned with an end of the curved surface and inclined at a pre-defined angle to manage and stabilize a compressed airflow. Further, the curved compression ramp assembly includes a leading edge of the curved compression ramp assembly positioned to generate a small flow deflection angle of the incoming high-speed airflow, and generate the oblique ramp shock wave transitioning into a curved shock wave profile due to interaction with the isentropic compression waves along the curved surface in the fore segment surface. Further, the CCR air intake apparatus includes a curved cowl assembly positioned opposite to the curved compression ramp assembly. The cowl assembly includes a cowl lip on the curved cowl assembly positioned downstream to the leading edge of the curved compression ramp assembly, to satisfy a shock-on-lip condition at a pre-determined location on the cowl lip. In an embodiment, the cowl lip may be positioned relative to the leading edge of the curved compression ramp assembly, based on at least one design configuration. Furthermore, the curved cowl assembly includes a concavely curved inner surface with the at least one design configuration and aligned with the curved compression ramp assembly to direct airflow into an isolator section with at least one of parallel walls and non-parallel walls downstream to the curved cowl assembly.
[0036] Referring now to the drawings, and more particularly to FIG. 3 through FIG. 12, where reference characters denote corresponding features consistently throughout the figures, there are shown preferred embodiments, and these embodiments are described in the context of the following exemplary system and/or method.
[0037] FIG. 3 illustrates a schematic representation of a Curved Compression Ramp (CCR) air intake apparatus 300 for ramjet engine and scramjet engine (not shown in FIG. 3), in accordance with an embodiment of the present disclosure. The CCR air intake apparatus 300 may include a Curved Compression Ramp (CCR) assembly 301, and a curved cowl assembly 307. The CCR assembly 301 may include a fore segment 301a, a planar aft segment 301b, and a leading edge 301c. The curved cowl assembly 307 may include a cowl lip 307a, a concavely curved inner surface 307b. For example, the CCR air intake apparatus 300 may be a structured component in an air intake system designed to compress incoming airflow efficiently using a curved ramp. The CCR assembly 301 may be a part of the air intake system that directs and compresses the airflow before the airflow enters the engine or combustion chamber. The fore segment 301a may be a front portion of the CCR assembly 301 where airflow first contacts the ramp. Furthermore, the planar aft segment 301b may be a slightly flatter, rear portion of the ramp that directs the compressed airflow further into the system, and the leading edge 301c may be a forwardmost part of the ramp that initially interacts with the airflow, playing a crucial role in aerodynamics and compression. Additionally, the curved cowl assembly 307 may be a structural component that encloses and directs airflow through the intake system. The curved cowl assembly 307 includes the cowl Lip 307a, which is an outermost edge of the cowl that interacts with incoming air, shaping the airflow into the intake. The curved cowl assembly 307 includes the concavely curved inner surface 307b, which may be an inner portion of the cowl that has a concave curvature, designed to optimize airflow direction and compression.
[0038] The Curved Compression Ramp (CCR) air intake apparatus 300 may be a specialized component used in advanced aerospace applications, particularly in hypersonic vehicles, spacecraft, High-Speed Civil Transport (HSCT), scramjet propulsion systems, drones and Unmanned Aerial Vehicles (UAVs), experimental aerospace vehicles, high-speed wind tunnel testing, aircraft, missile designs and the like. For example, primary purpose of the CCR air intake apparatus 300 may be to manage the airflow entering the engine or propulsion system, ensuring that the air pressure is increased (compressed) in a controlled and efficient manner as the air flows towards a combustor of an engine. Further, aspects of the CCR air intake apparatus 300 may include compression and curvature. As air flows through an intake system, the air needs to be compressed before it enters combustion chambers of the engine. Higher pressure is critical for engine efficiency and performance, especially in high-speed or supersonic flight. Further, a ramp refers to a physical surface or surface feature within the intake that changes the direction and pressure of the incoming airflow. Typically, this ramp is angled or curved to create shock waves or cause air deceleration, leading to increased pressure. Curvature is a curved nature of the compression ramp that helps in managing the air flow in a more gradual and controlled manner. The curvature also helps in ensuring that shock waves (from supersonic air intake) are directed in a way that optimizes the pressure increase without causing excessive drag or stagnation pressure losses.
[0039] In high-speed aircraft, especially those that travel at supersonic speeds (greater than the speed of sound), air entering the engine is initially moving at a high velocity. A direct entry of this high-speed air into the engine would be inefficient and could cause damage. Further, the CCR air intake uses curved compression ramp to create a controlled series of shock waves and compression waves as the fast-moving air decelerates. The ramp’s design deflects the airflow, causing it to slow down in stages, which results in a gradual compression of the air. By the time the air flow enters the combustor, the pressure of the air flow may be high enough for efficient functioning of the engine, particularly for engines designed for supersonic and hypersonic flight, such as ramjets and scramjets.
[0040] In an example, the curved ramp helps in smooth air compression, leading to more efficient operation of the engine. The controlled compression helps maintain stability of the engine, even at high speeds, and improves its thrust-to-weight ratio. The CCR intake is particularly effective in supersonic and hypersonic flight. CCR intakes are commonly used in advanced aircraft/jets, which operate at supersonic speeds and hypersonic speeds and need to efficiently manage airflow into the engine at high Mach numbers. The precise angle and curvature of the ramp must be carefully designed to achieve the desired compression without causing excessive drag. Since the intake system operates under high-speed and high-temperature conditions, materials used for CCR ramps must be heat-resistant and capable of withstanding the extreme aerodynamic forces.
[0041] The CCR air intake apparatus 300 may include the Curved Compression Ramp (CCR) assembly 301 configured to perform flow shaping of incoming high-speed airflow. Further, the CCR assembly 301 may include the fore segment 301a with a curved surface configured to induce a curved shock wave 303 through an interaction of an oblique ramp shock wave and a continuous series of isentropic compression waves 305 emanating from the curved surface of the CCR assembly 301. In an embodiment, the curved surface of the CCR assembly 301 may generate a series of compression waves 305 that progressively and isentropically compress the airflow. In an embodiment, the fore segment 301a may include for example, but not limited to, a geometry configured to generate at least, for example, but not limited to, one gradient such as a constant pressure gradient, and the like, in a freestream direction along the CCR assembly 301 for a pre-defined design Mach number. The at least one gradient may include for example, but not limited to, pressure gradient, a Mach number gradient, a flow density gradient, and the like. Further, in an embodiment, the CCR assembly 301 may be configured to optimize intake stability to mitigate boundary layer effects.
[0042] Further, the CCR assembly 301 may include a planar aft segment 301b downstream of the curved surface configured to manage and stabilize the airflow. In an embodiment, the planar aft segment 301b may be tangentially aligned with an end of the curved surface and inclined at a pre-defined angle to manage and stabilize a compressed airflow. Further, the CCR assembly 301 may include a leading edge 301c of the curved compression ramp assembly 301 positioned to generate a small flow deflection angle (?i) of the incoming high-speed airflow, and generate the oblique ramp shock wave (shown as an enlarged view in FIG. 3) transitioning into a curved shock wave 303 profile due to interaction with the isentropic compression waves 305 along the curved surface in the fore segment 301a surface. For example, the leading edge 301c may be configured to generate weak oblique shock waves, in which the generated weak oblique shock waves interact with the compression waves 305 to generate a curved shock wave 303. For example, the small flow may be a slight deflection of the incoming high-speed airflow as the air flow interacts with the leading edge 301c of the CCR assembly 301. The leading edge 301c is positioned at an angle that causes a minor change or deflection in the direction of the airflow. This deflection is not large but significant enough to influence the airflow characteristics. As the airflow is deflected, it interacts with the isentropic compression waves 305 along the curved surface of the ramp. The small flow deflection angle may fall within a range of few degrees, depending on the design requirements and operating conditions. For mild compression ramps, the deflection angle is usually few degrees to prevent excessive shock losses and maintain high total pressure recovery. For stronger compression effects, such as in mixed compression inlets, the deflection may be few degrees, optimizing both oblique and curved shock formations.
[0043] The CCR air intake apparatus 300 may further include the curved cowl assembly 307 positioned opposite to the curved compression ramp assembly 301. The curved cowl assembly 307 may include a cowl lip 307a on the curved cowl assembly 307 positioned downstream to the leading edge 301c of the curved compression ramp assembly 301, to satisfy a shock-on-lip condition at a pre-determined location on the cowl lip 307a. In an embodiment, the cowl lip 307a may be positioned relative to the leading edge 301c of the curved compression ramp assembly 301, based on at least one design configuration. The at least one design configuration may include at least one of, but not limited to, Strong Shock Design (SSD) principle/ technique/configuration, and the like. Further, the curved cowl assembly 307 may include a concavely curved inner surface 307b with the at least one design configuration and aligned with the curved compression ramp assembly 301 to direct airflow into an isolator section with at least one of, for example, but not limited to, parallel walls, and non-parallel walls downstream to the curved cowl assembly 307. The at least one design configuration may include at least one of, but not limited to, inverse design principle/technique/configuration, and the like.
[0044] In an embodiment, the total flow-turning angle induced by the CCR assembly 301 may be represented as ‘d’ (as shown in FIG. 3). Further, the curved shock wave 303 may reflect off the cowl lip 307a as a terminal shock 309 (as shown in FIG. 3). Further, in an embodiment, a normal line 311 dropped from the cowl lip 307a of the curved cowl assembly 307, on the planar portion of the CCR assembly 301, may demarcate the external compression section from the internal compression section. For example, a Mach number distribution along the normal line 311 may be non-uniform due to the curved nature of the curved shock wave 303, with the local Mach number being maximum at the surface of the CCR assembly 301 and decreasing monotonically to a minimum at the curved cowl assembly 307.
[0045] FIG. 4 illustrates a schematic diagram representation 400 of a supersonic or hypersonic flow past a curved compression wedge at zero-angle of attack, in accordance with an embodiment of the present disclosure. As shown in FIG. 4, the curvature of the curved shock wave 303 may be clearly seen in representation 400.
[0046] In an embodiment, the placement of the curved cowl assembly 307 is of utmost importance which would determine the overall performance of the intake of the airflow, not just at the design condition, and at different off-design conditions that the vehicle may experience during flight (deviations from design angle of attack while maneuvering, fluctuations in pressure due to combustor). The startability of an intake may be determined by its ability to capture all the high-speed flow that enters its inlet area, represented as A?? (as shown in FIG. 3). Further, the curved cowl assembly 307 may be positioned to satisfy shock on lip condition. For example, the curved cowl assembly 307 is positioned opposite to the CCR assembly 301. The cowl lip 307a is positioned downstream to the leading edge of the CCR assembly 301. While there may be multitude of locations along the curved shock wave 303, where the curved cowl assembly 307 may be positioned, it is important to assess the influence of the effect of each of these positions on the efficiency of the intake. When not positioned carefully, the intake of the airflow may turn out to be unstable and sensitive even to minute perturbations, eventually leading to engine failure. Therefore, careful placement of the curved cowl assembly 307 may be important for the resilient performance of the intake. As the shock on lip condition may need to be satisfied for the intake of the airflow to remain started, and to be able to capture all of the flow entering the inlet area (A??), high-speed air intakes may be sensitive to even minute changes in angle of attack, resulting in unstable operation eventually leading to engine failure. This is because, with a change in vehicle orientation (angle of attack), the shock structure may also change.
[0047] In an embodiment, the extent of compression achieved by the intake of the airflow may also depend on the location of the curved cowl assembly 307 (designed according to at least, but not limited to, strong shock design principle, and the like), as it may determine the nature of the second shock wave. Further, the overall compression may depend on the entire shockwave system. Moreover, curvature of the curved cowl assembly 307 may be carefully designed to get a desired flow distribution once again, taking into consideration the robust off-design performance needed for such an intake of the airflow.
[0048] In an embodiment, the optimal combination of the CCR assembly 301, the curved cowl assembly 307, and strong shock design principle employed in this design results in exemplary performance in comparison with the conventional and contemporary intake designs. The present disclosure provides performance (from experimental examination), supreme maneuverability using the CCR intake apparatus. The resilience of this model has been experimentally demonstrated, wherein the intake reverts to a stable operating state (started state) from an undesirable operating state (un-started intake) on appropriately adjusting the isolator pressure value. Intake un-starts (potential engine failure) at thrice the pressure ratio value at which we detect that it is about to unstart (signs of engine failure). It is helpful in the design of early unstart warning systems.
[0049] The contour of the CCR assembly 301 may be estimated based on the analytical framework proposed in our recent work for choosing an optimal design configuration with robust performance. The design methodology followed for the determination of the cowl lip 307a location is unique. This step forms the crux of all the advantages that have been perceived for this design compared to the existing conventional high-speed air-intakes. The resulting design has demonstrated very high maneuverability and efficiency in comparison with the conventional designs. It is robust to the combustor-driven isolator back pressure fluctuations and angle of attack variation that would be encountered in real flight scenarios.
[0050] FIG. 5 illustrates a side view of a schematic diagram representation of an exemplary model of Curved Compression Ramp (CCR) assembly 301, in accordance with an embodiment of the present disclosure.
[0051] In an example embodiment, two unique aspects of the CCR air intake apparatus 300 of a scramjet engine may include a design procedure generic for any freestream Mach number, and a design configuration designed, for example, for Mach 6. For example, the design procedure generic for any freestream Mach number may include a design methodology and procedure, which may be universally applied to design an optimal CCR air intake apparatus 300 for any supersonic freestream Mach number. The steps involved in the comprehensive design procedure includes, but not limited to, choosing the CCR assembly 301 geometry, estimating cowl lip 307a coordinates, satisfying the shock-on-lip condition, adjusting coordinates based on experimental data, designing the curved cowl assembly 307 and an isolator 501 (as shown in FIG. 5) walls, and the like. Further, in an embodiment, choosing the CCR assembly 301 geometry may include an initial step which involves selecting the appropriate geometry of the CCR assembly 301 for a given freestream Mach number. This may be based on the analytical framework, which aims to for example, but not limited to, design an intake configuration capable of self-starting for a strong shock design, and the like.
[0052] Furthermore, estimating cowl lip 307a coordinates represented as (xcowl, ycowl) may include estimating the coordinates of the cowl lip 307a relative to the leading-edge 301c coordinates represented as (xi, yi) (as shown in FIG. 5) of the CCR assembly 301, using for example, but not limited to, the Strong Shock Design (SSD) principle, and the like. This may ensure that the cowl lip 307a may be correctly positioned to interact with the curved shock wave 303. Further, in an embodiment, the curved shock wave 303 may impinge directly on the cowl lip 307a, to satisfy the shock-on-lip condition. The analytical algorithm used for initial design may not account for the boundary layer, as shown in FIG. 4.
[0053] Further, in an embodiment, adjusting coordinates of the cowl lip 307a may be based on experimental data which may further include retaining the x-coordinate (xcowl) derived from the analytical framework, using the strong shock design principle. However, the y-coordinate (ycowl) of the cowl lip 307a, may be corrected according to the shock profile obtained from experimental schlieren (flow visualization) results. This may ensure the shock-on-lip condition is met accurately. Furthermore, designing the curved cowl assembly 307 and the isolator 501 walls may include designing the curved cowl assembly 307 with a curved contour which may be concave, based on the inverse design principle. In other words, the curved cowl assembly 307 may include contour in concave shape and designed according to the at least one design configuration.
[0054] Moreover, the walls of the isolator 501 may be parallel to the direction of the freestream flow, facilitating optimal airflow through the air intake (not shown in FIG. 5). In an embodiment, the CCR air intake apparatus 300 may include an isolator 501 section downstream of the curved cowl assembly 307. The isolator 501 may include the parallel walls configured to guide the compressed airflow towards a downstream combustor (not shown in FIG. 5) while maintaining airflow stability, in which the parallel walls may be aligned to at least one of, for example, but not limited to, a pre-defined angle. The pre-defined angle may include, for example, but not limited to, 00 and/or any acute angle. Further, a feedback control system may be coupled between the isolator 501 and the combustor. The feedback control system may be configured to monitor isolator 501 back pressure and dynamically adjust a fuel flow rate of a combustor associated with at least one of ramjet and scramjet engines, for reversion to a stable operating state and recovery from an un-started state, in which the fuel flow rate may be adjusted for controlling pressure fluctuations induced by the combustor. In an embodiment, the isolator back pressure may be induced by the combustor at the isolator 501 exit of the at least one of ramjet and scramjet engines.
[0055] Further, in an embodiment, the CCR air intake apparatus 300 may include a sensor array positioned along the CCR assembly 301, the curved cowl assembly 307, and the isolator 501 section to monitor one or more parameters and one or more flow parameters, in which the sensor array may be configured to generate sensor data to be utilized by the feedback control system to maintain stable intake operation, and to adjust the fuel flow rate in the combustor to manage the pressure at the isolator 501 exit. In an embodiment, the one or more parameters may include, for example, but not limited to, at least one of a pressure, a temperature, a Mach number, density gradient, parameters measured using one or more optical diagnostic techniques, and aero-dynamic flow parameters, and the like.
[0056] In an example scenario, a specific design configuration, for example, for Mach 6 may include designing the CCR intake model and testing for Mach 6 demonstrated exceptional performance compared to conventional intake designs. The primary objective may be to develop a fixed geometry intake that could self-start at Mach 6 while maintaining excellent performance under off-design conditions. Key aspects of this configuration may include, but not limited to, two-dimensional ramp design, initial planar section, curved segment for isentropic compression, downstream planar section, interaction of compression waves and shock waves, physical dimensions, and the like. Two-dimensional ramp design may include the CCR assembly 301, which may further create at least one gradient (e.g., gradient of a flow parameter) along the freestream direction for a Mach 6 inviscid flow at a zero angle of attack (a = 0). This design may ensure efficient compression and management of high-speed flows. The CCR assembly 301 may include a short planar section at the leading edge 301c angled at, for example, but not limited to, ?i = 4° at the leading edge 301c. Along the surface of the curved section, the flow undergoes isentropic compression from a Mach number ??1 immediately downstream of the leading edge shock wave to a reduced Mach number ??C, which may be set at for example, 4. Following the curved segment, there is another planar section downstream, set tangential to the curved segment at its end, inclined at for example, ?? = 19.05o relative to the freestream direction. A continuous series of compression waves from the curved surface interact with the oblique shock wave generated at the leading edge, causing it to curve gradually and form the observed concave shape.
[0057] Further, in an embodiment, a continuous series of compression waves 305 from the fore segment 301a may interact with the oblique shock wave generated at the leading edge 301c. This interaction may cause the oblique shock wave to gradually curve into a concave shape to generate a curved shock wave 303, optimizing the compression process and reducing potential stagnation pressure losses. In an embodiment, Table 1 represented below, may represent physical dimensions of the CCR air intake apparatus 300 that may provide a comprehensive overview of the geometric parameters and their impact on the performance of the intake of the airflow.
Geometric parameters Length
Location of the leading edge of the compression ramp, ???? 0.00 mm
y-coordinate of the leading edge of the compression ramp, y?? 0.00 mm
Location of the initial point of the curvature along the compression ramp, ???? 10.00 mm
Location of the terminal point of the curvature along the compression ramp, ???? 70.00 mm
Location of the expansion corner of the compression ramp, ????h 100.00 mm
Location of the isolator back pressure measurement probe, ???? 170.50 mm
Location of the sliding plate, ?????? 227.84 mm
Location of the isolator exit, ???????? 250.00 mm
Height of the intake inlet area, H?? 36.50 mm
Height of the isolator, ???????? 12.10 mm
Width of the intake model (in the spanwise direction), ?? 100.00 mm
x-coordinate of the cowl lip, xcowl 96.30 mm
y-coordinate of the cowl lip, ycowl 36.52 mm
Table 1: Physical dimensions of the CCR air intake apparatus.

[0058] By following the methodical design procedure as shown in Table 1, the present disclosure may ensure optimal performance at supersonic and hypersonic freestream Mach numbers, particularly demonstrating superior capabilities at, for example, Mach 6.
[0059] FIG. 6 illustrates a schematic diagram representation of an exemplary CCR air intake apparatus 300 including a provision for isolator back pressure variation, in accordance with an embodiment of the present disclosure.
[0060] In an example, the CCR air intake apparatus 300 may be strut-mounted in the wind tunnel test section (not shown in FIG. 6). For example, in an experimental setup, a sliding plate 601 may be used to induce isolator back pressure variation in the isolator 501 section, to replicate the combustor pressure. The pressure fluctuations induced by a combustor in an actual engine were simulated by using a sliding plate that varies the pressure induced by varying the blockage. The throttling ratio may be defined as the percentage of blockage produced by the sliding plate 601 in the isolator 501 section. For example, the throttling ratio may be represented as shown in equation (1) below:
(???? = ??????/???????? x 100) ------------(1)
[0061] By altering the area blockage through the movement of the sliding plate 601, the throttling ratio of the isolator 501 may be adjusted, causing changes in isolator back pressure. This arrangement may mimic the isolator back pressure variation induced by a combustor (not shown in FIG. 6) at the exit of the isolator 501 of an actual engine. Further, the motion of the sliding plate 601 may be precisely controlled using a lead screw 603 mechanism actuated by a stepper motor 605. The sliding plate 601 may be inclined at for example, but not limited to, 25 degrees to prevent the formation of a detached shock wave in the isolator 501 section.
[0062] FIG. 7 illustrates a side view of a schematic diagram representation of an exemplary Curved Compression Ramp (CCR) air intake apparatus 300 strut-mounted in an example test-section of a wind tunnel for isolator back pressure variation studies, in accordance with an embodiment of the present disclosure.
[0063] In an embodiment, the resilience and reversion to started state, may include demonstrating the intake significant resilience by reverting back to its started state when desirable isolator 501 pressure values are achieved. In an embodiment, the isolator 501 pressure may be intentionally increased to induce an unstable operating state (un-started state) by increasing the exit blockage through the upward movement of a sliding plate 601. Subsequently, the sliding plate 601 may be lowered to reduce the blockage and thereby decrease the isolator 501 back pressure. Upon reducing the isolator back pressure, the intake may be returned to stable operating state (started state). This capability may be crucial for engine operation, suggesting that engine failure may be prevented, and the engine may be revived by appropriately adjusting the fuel flow rate in the combustor (not shown in FIG. 7). Further, an appropriate feedback loop system may be designed to monitor and control the intake unstart condition, with the ideal location for installing a sensor for isolator 501 pressure measurements (pb) as shown in Table 1.
[0064] FIG. 8 illustrates schematic diagram representations of different states of intake operation and flow features of the CCR air intake apparatus 300 based on variations in isolator 501 back pressure, in accordance with an embodiment of the present disclosure.
[0065] In an embodiment, engine revival and failure prevention may include the ability to revive the engine and prevent engine failure by managing the isolator 501 back pressure through adjustments in the fuel flow rate. By incorporating an appropriate feedback loop system that may continuously monitor the isolator 501 pressure, the CCR air intake apparatus 300 may dynamically adjust to maintain the air intake in the started state. This proactive management of isolator 501 pressure may ensure the air intake remains stable, thereby enhancing the reliability and efficiency of the engine. Further, the specific location for pressure sensor installation, may be critical for accurate pressure monitoring and effective feedback loop operation. Moreover, by varying the isolator 501 back pressure, FIG. 8 may demonstrate robustness and superiority of the Curved Compression Ramp (CCR) air intake apparatus 300 over conventional designs.
[0066] In an embodiment, the resilience and reversion to started state, includes demonstrating the intake significant resilience by reverting back to its started state when desirable isolator pressure values are achieved. The isolator 501 pressure may be intentionally increased to induce an unstable operating state (un-started state) by raising the exit blockage through the upward movement of the sliding plate 601. Subsequently, the sliding plate 601 may be lowered to reduce the blockage and thereby decrease the isolator 501 back pressure. Upon reducing the isolator back pressure, the intake may be returned to stable operating state (started state).
[0067] For example, (a) of FIG. 8 represents a started intake with zero blockage. Further, (b) of FIG. 8 represents intermediate stage of operation with a moderate blockage. Furthermore, (c) of FIG. 8 represents an un-started intake with shock system disgorged from the isolator 501 at an extremely high blockage.
[0068] FIG. 9 illustrates an exemplary graph diagram representation of a variation in isolator back pressure ratio and throttling ratio as a function of time, in accordance with an embodiment of the present disclosure.
[0069] In an embodiment, the characteristic of the CCR air intake apparatus 300 highlights the robustness of the design with respect to the isolator 501 back pressure rise induced by the combustor that may lie downstream to the isolator 501. The ideal location of the isolator 501 back pressure measurement probe, ‘????’ for detecting the pressure fluctuations and the state of operation of the CCR air intake apparatus 300 is specified in Table 1. Further, the variation in the isolator 501 back pressure ratio, ????/??8 with respect to the throttling ratio, ‘????’ may be plotted as a function of time in graph of FIG. 9 with different states of intake operation demarcated. For example, as shown in graph of FIG. 9, (1) may be represented as commencement of strong shock wave propagation, (2) may be represented as onset of intake un-start, and (3) may be represented as onset of intake buzz phenomenon.
[0070] FIG. 10 illustrates a schematic diagram representation of the CCR air intake apparatus 300 used for angle-of-attack variation studies, in accordance with an embodiment of the present disclosure.
[0071] For example, as shown in FIG. 10, a rake 1001 may be used for estimation of distribution of Mach number and pressure recovery (efficiency) in cross-stream direction inside the isolator 501 section. In an example, the CCR air intake apparatus 300 may be sting-mounted to a support sector installed in the test-section of the wind tunnel. The angle of attack of the intake model may be increased from for example, but not limited to, -7.5° to 21° at the rate of around 8°/s during the course of a blowdown. In an embodiment, the positive angle may denote an increase in the total flow deflection angle induced by the CCR assembly 301. This set-up may further evaluate the maneuverability of the scramjet intake with respect to the variation in the flight angle of attack. The variation in the intake efficiency (stagnation pressure recovery) with respect to the angle of attack may also be estimated using the example experimental set-up.
[0072] FIG. 11 illustrates schematic diagram representations of different states of intake operation and flow features of the CCR air intake apparatus 300 based on variation in angle of attack, in accordance with an embodiment of the present disclosure.
[0073] In an embodiment, the CCR air intake apparatus 300 may remain in the stable operating state (started state) over a wide range of angles of attack (0° to around 10°), with shock on lip condition being satisfied throughout this range of angles of attack, i.e., the CCR air intake apparatus 300 may be capturing all of the flow entering an inlet area (Ai) throughout this range of angle of attack variation. The inlet area (Ai) may be an area obtained by projecting the planar surface spanning the line joining the leading edge of the CCR assembly 301 and the cowl lip 307a axially to the freestream flow. This may also provide a wide spectrum of attack angles for picking the design angle of attack of the CCR air intake apparatus 300. At further higher angles of attack up to 21o, although there may be a spillage with all the flow entering the inlet area not getting ingested by the CCR air intake apparatus 300, the flow in the isolator 501 may continue to be supersonic. Over this range of angle of attack (10° to 21°), although the intake efficiency is not at its best, the engine may be still fail-safe. For example, throughout the range of angle of attack (10° to 21°), the CCR air intake apparatus 300 may be transitioned between started state, stage 1 of intake unstarts, and stage 2 of intake unstart. Even at extremely high angle of attack, the CCR air intake apparatus 300 may not reach stage 3 of intake unstart, in which at the point of stage 3 of intake unstart, the CCR air intake apparatus 300 may be prone to a non-revivable mode of engine failure.
[0074] An extremely high intake efficiency (stagnation pressure recovery of close to 40%) may be estimated over a sub-range of angles of attack (3° to 6°) within the range of angles of attack in which the intake is operating in the started state.
[0075] In an embodiment, the intake may remain in the stable operating state (started state) over a wide range of angles of attack (00 to around 100), with shock on lip condition being satisfied throughout this range of angles of attack, i.e., the intake is capturing all of the flow entering the inlet area (Ai) throughout this range of angle of attack variation. This also provides a wide spectrum of attack angles for picking the design angle of attack of the intake model. At further higher angles of attack up to 200, although there is spillage with all the flow entering the inlet area (Ai) not getting ingested by the intake, the flow in the isolator 501 continues to be supersonic. Over this range of angle of attack (100 to 20.50), although the intake efficiency is not at its best, the engine is still fail-safe. Further, a capture area (Acap) may be a throughflow area of the freestream flow entering the geometric opening of the intake.
[0076] For example, (a) of FIG. 11 represents started intake at the design angle of attack. Further, (b) of FIG. 11 represents first stage of intake unstart indicating a minute flow spillage. Furthermore, (c) of FIG. 11 represents second stage of intake unstart indicating a detached shockwave at the cowl lip 307a. Subsequently, (d) of FIG. 11 represents third stage of the intake unstart indicating a shockwave system disgorged from the isolator 501.
[0077] FIG. 12 illustrates a flow chart representation of a method 1200 for managing high-speed airflow in a Curved Compression Ramp (CCR) air intake apparatus 300 for ramjet engine and scramjet engine, in accordance with an embodiment of the present disclosure.
[0078] At step 1201, the method 1200 includes generating, by the CCR air intake apparatus 300, an initial oblique ramp shock wave at a leading edge 301c of the CCR assembly 301 by generating a small flow deflection angle in the incoming airflow.
[0079] At step 1202, the method 1200 includes inducing, by the CCR air intake apparatus 300, a curved shock wave 303 through an interaction of the oblique ramp shock wave with a series of isentropic compression waves 305 along a curved fore segment 301a of the CCR assembly 301.
[0080] At step 1203, the method 1200 includes stabilizing and managing, by the CCR air intake apparatus 300, the compressed airflow in a planar aft segment 301b tangentially aligned with an end of the curved fore segment 301a, in which the planar aft segment 301b may be inclined at a pre-defined angle.
[0081] At step 1204, the method 1200 includes aligning, by the CCR air intake apparatus 300, a leading-edge portion of an isolator top-plate including a concavely curved inner surface of the curved cowl assembly 307 to guide the airflow into the isolator 501 section.
[0082] At step 1205, the method 1200 includes configuring, by the CCR air intake apparatus 300, a cowl lip 307a of the curved cowl assembly 307 to satisfy a shock-on-lip condition at a pre-defined location relative to the leading edge 301c of the CCR assembly 301, in which the cowl lip 307a may be positioned relative to the leading edge 301c of the curved compression ramp assembly 301, based on at least one design configuration, in which the cowl lip 307a location may be optimized for intake stability and capture efficiency under both design and off-design conditions.
[0083] The present disclosure discloses use of a Curved Compression Ramp (CCR) intake which combines the advantages of simple ramp intake or multi-step ramp intake and isentropic designs such as a Busemann intake and a Prandtl-Meyer intake. More specifically, the CCR intake generates a weak oblique shock wave at the leading edge of a ramp, which gets gradually strengthened downstream through interaction with compression waves produced by the curvature of the ramp. This design approach enhances compression capability and efficiency while reducing the overall length of the intake compared to other contemporary and conventional designs.
[0084] Further, the CCR intakes with at least one gradient along the curved wall enable superior resistance to boundary layer separation compared to multi-step ramp intake designs. For example, the at least one gradient may include, but not limited to, a pressure gradient, flow density gradient, and the like. Furthermore, CCR intakes are more practical due to their shorter length compared to purely isentropic intakes. Furthermore, the CCR intakes provide better pressure recovery and performance at off-design conditions. These intakes provide a shorter compression ramp length and stable boundary layers, contributing to their overall effectiveness. Design variations, such as weak and strong shock configurations, also influence intake performance, with strong shock designs generally providing improved startability and robustness against back-pressure variations.
[0085] Further, the present disclosure facilitates the use of a curved cowl lip, which helps to reduce the strength of terminal shock waves and minimize separation bubble size at the expansion corner, enhancing overall performance of the intake.
[0086] Further, in comparison with the existing conventional multi-step ramp intakes and other isentropic intakes, the curved compression ramp employed in the present disclosure is shorter in length for the same mass flow rate captured and promises improved performance. Further, the broad range of isolator pressure values observed in the intermediate state (intake unstarts at almost thrice the isolator pressure value at which the onset of unstart is observed) provides a sufficient window to act and prevent the engine from failure.
[0087] Moreover, the use of a curved compression ramp mitigates the issue of boundary layer separation that is usually observed for conventional intake designs at high angles of attack. Furthermore, the present disclosure provides very high maneuverability in terms of angle of attack variation, with the intake remaining in the stable operating state (started state) over a wide range of angles of attack (for example, 0° to around 10°), thereby enabling a wide spectrum of angles of attack for picking the design angle of attack of the intake model. Subsequently, the present disclosure achieves an extremely high compression efficiency (stagnation pressure recovery of 40%) over a sub-range of angles of attack (3° to 6°).
[0088] Various embodiments of the present disclosure enable an intake with high robustness to off-design conditions, including variations in combustor-driven isolator pressure and changes in the vehicle's angle of attack. A unique aspect of the present disclosure includes the design procedure which is versatile and can be applied to create an optimal CCR intake for any supersonic freestream Mach number. This generic methodology ensures that the design can be adapted to various conditions, making it highly flexible and applicable to a wide range of scenarios. The CCR intake model adheres to the strong shock design principle, with the location of the curved cowl assembly 307 relative to the leading edge of the CCR assembly being a crucial factor.
[0089] The combination of a CCR assembly, curved cowl assembly 307, and strong shock design principle results in exceptional performance compared to conventional intake designs. The CCR air intake apparatus is notably shorter, experiences less drag and other aerothermal loads and achieves significantly higher efficiency than traditional high-speed air intakes. The optimal location of the cowl lip relative to the CCR assembly, determined through thorough analytical and experimental studies, is central to the remarkable performance of this intake. This positioning differentiates the CCR intake from conventional and contemporary intake geometries. The CCR intakes may also be referred to as isentropic intakes. However, the compression ramp geometrics of the isentropic intakes may be tuned based on design requirements.
[0090] Further, the CCR intake showcases supreme maneuverability. It operates efficiently over a broad range of angles of attack in the started state and maintaining a fail-safe mode. This extensive operability range is unprecedented for high-speed air intakes designed for Mach 6. The resilience of this model has been experimentally demonstrated, with the intake reverting to a stable operating state from an un-started state by adjusting the isolator pressure appropriately. Additionally, the intake enables a wide margin of combustor pressure variation at the isolator exit before unstarting, providing a significant window to prevent engine failure. The intake unstarts at a pressure value for example, nearly three times the isolator pressure observed at the onset of unstart. A proposed sensor location for pressure measurement can be used to design a feedback loop to prevent engine failure by adjusting the fuel flow rate in the combustor to manage the pressure at the isolator exit.
[0091] The contour of the CCR assembly may be determined using the analytical framework, which ensures an optimal design configuration with robust performance. The unique methodology for determining the cowl lip location is key to the advantages of this design compared to existing high-speed air intakes. The design demonstrates high maneuverability and efficiency, being robust to combustor-driven isolator back pressure fluctuations and angle of attack variations in real flight scenarios.
[0092] One of the ordinary skills in the art will appreciate that techniques consistent with the present disclosure are applicable in other contexts as well without departing from the scope of the disclosure.
[0093] What has been described and illustrated herein are examples of the present disclosure. The terms, descriptions, and figures used herein are set forth by way of illustration only and are not meant as limitations. Many variations are possible within the scope of the subject matter, which is intended to be defined by the following claims and their equivalents in which all terms are meant in their broadest reasonable sense unless otherwise indicated.
[0094] The written description describes the subject matter herein to enable any person skilled in the art to make and use the embodiments. The scope of the subject matter embodiments is defined by the claims and may include other modifications that occur to those skilled in the art. Such other modifications are intended to be within the scope of the claims if they have similar elements that do not differ from the literal language of the claims or if they include equivalent elements with insubstantial differences from the literal language of the claims.
[0095] The embodiments herein may include hardware and software elements. The embodiments that are implemented in software include but are not limited to, firmware, resident software, microcode, and the like. The functions performed by various modules described herein may be implemented in other modules or combinations of other modules.
[0096] A description of an embodiment with several components in communication with each other does not imply that all such components are required. On the contrary, a variety of optional components are described to illustrate the wide variety of possible embodiments of the invention. When a single device or article is described herein, it will be apparent that more than one device/article (whether or not they cooperate) may be used in place of a single device/article. Similarly, where more than one device or article is described herein (whether or not they cooperate), it will be apparent that a single device/article may be used in place of the more than one device or article, or a different number of devices/articles may be used instead of the shown number of devices or programs. The functionality and/or the features of a device may be alternatively embodied by one or more other devices which are not explicitly described as having such functionality/features. Thus, other embodiments of the invention need not include the device itself.
[0097] The illustrated steps are set out to explain the exemplary embodiments shown, and it should be anticipated that ongoing technological development will change the manner in which particular functions are performed. These examples are presented herein for purposes of illustration, and not limitation. Further, the boundaries of the functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternative boundaries may be defined so long as the specified functions and relationships thereof are appropriately performed. Alternatives (including equivalents, extensions, variations, deviations, and the like., of those described herein) will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein. Such alternatives fall within the scope of the disclosed embodiments. Also, the words "comprising," "having," "containing," and "including," and other similar forms are intended to be equivalent in meaning and be open-ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items or meant to be limited to only the listed item or items. It must also be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.
[0098] Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the invention be limited not by this detailed description, but rather by any claims that issue on an application based here on. Accordingly, the embodiments of the present invention are intended to be illustrative, but not limited, of the scope of the invention, which is outlined in the following claims.
REFERRAL NUMERALS:
Reference number Description
300 Curved Compression Ramp (CCR) air intake apparatus
301 Curved Compression Ramp (CCR) assembly
301a Fore segment
301b Planar aft segment
301c Leading edge
303 Curved shock wave
305 Compression wave
307 Cowl assembly
307a Cowl lip
307b Curved inner surface
309 Terminal shock
311 Normal line
400 Schematic representation
501 Isolator
601 Sliding plate
603 Lead screw
605 Stepper motor

,CLAIMS:We claim:

1. A Curved Compression Ramp (CCR) air intake apparatus (300) for ramjet and scramjet engines, comprising:
a Curved Compression Ramp (CCR) assembly (301) configured to perform flow shaping of incoming high-speed airflow, wherein the CCR assembly (301) comprises:
a fore segment (301a) with a curved surface configured to induce a curved shock wave (303) through an interaction of an oblique ramp shock wave and a continuous series of isentropic compression waves (305), wherein the curved surface generates a series of compression waves (305) that progressively and isentropically compress the incoming high-speed airflow;
a planar aft segment downstream (301b) of the curved surface configured to manage and stabilize the airflow, wherein the planar aft segment (301b) is tangentially aligned with an end of the curved surface, and inclined at a pre-defined angle to manage and stabilize a compressed airflow; and
a leading edge (301c) of the CCR assembly (301) positioned to generate a small flow deflection angle of the incoming high-speed airflow, and generating the oblique ramp shock wave transitioning into a curved shock wave (303) profile due to interaction with the isentropic compression waves (305) along the curved surface in a surface of the fore segment (301a); and
a curved cowl assembly (307) positioned opposite to the CCR assembly (301), the curved cowl assembly (307) comprising:
a cowl lip (307a) on the curved cowl assembly (307) positioned downstream to the leading edge (301c) of the CCR assembly (301), to satisfy a shock-on-lip condition at a pre-determined location on the cowl lip (307a), wherein the cowl lip (307a) is positioned relative to the leading edge (301c) of the CCR assembly (301), based on at least one design configuration; and
a concavely curved inner surface (307b) with the at least one design configuration and aligned with the CCR assembly (301) to direct airflow into an isolator (501) section with at least one of parallel walls, and non-parallel walls downstream to the curved cowl assembly (307).

2. The CCR air intake apparatus (300) as claimed in claim 1, further comprises:
the isolator (501) section downstream of the curved cowl assembly (307), comprising:
the parallel walls configured to guide the compressed airflow towards a downstream combustor while maintaining airflow stability, wherein the parallel walls are aligned to a pre-defined angle;
a feedback control system coupled to the isolator (501) section, configured to monitor isolator back pressure and dynamically adjust a fuel flow rate of a combustor associated with at least one of ramjet and scramjet engines, for reversion to a stable operating state and recovery from an un-started state, wherein the fuel flow rate is adjusted for controlling pressure fluctuations induced by the combustor, wherein the isolator back pressure is induced by the combustor at an isolator exit of the at least one of ramjet and scramjet engines; and
a sensor array positioned along the CCR assembly (301), the curved cowl assembly (307), and the isolator (501) section to monitor one or more flow parameters, wherein the sensor array is configured to generate sensor data to be utilized by the feedback control system to maintain stable intake operation, and to adjust the fuel flow rate in the combustor to manage the back pressure at the isolator exit.

3. The CCR air intake apparatus (300) as claimed in claim 1, wherein the fore segment (301a) comprises a geometry configured to generate at least one gradient in a freestream direction along the CCR assembly (301) for a pre-defined design Mach number.

4. The CCR air intake apparatus (300) as claimed in claim 1, wherein the CCR assembly (301) is configured to optimize intake stability to mitigate boundary layer effects.

5. The CCR air intake apparatus (300) as claimed in claim 1, wherein the curved shock wave (303) reflects off the cowl lip (307a) as a terminal shock (309), and a normal line (311) dropped from the cowl lip (307a) on a planar portion of the CCR assembly (301) demarcates an external compression section from an internal compression section.

6. The CCR air intake apparatus (300) as claimed in claim 5, wherein, along the normal line (311), a Mach number distribution is non-uniform due to a curved nature of an upstream shock wave, wherein the Mach number comprises a local Mach number being maximum at a surface of the ramp decreases monotonically and attains a minimum value at the cowl lip (307a) of the curved cowl assembly (307).

7. The CCR air intake apparatus (300) as claimed in claim 1, wherein the curved cowl assembly (307) comprises contour in concave shape and designed according to the at least one design configuration.

8. The CCR air intake apparatus (300) as claimed in claim 2, wherein the one or more flow parameters comprise at least one of a pressure, a temperature, a Mach number, density gradient, parameters measured using one or more optical diagnostic techniques, and aero-dynamic flow parameters.

9. A method for managing high-speed airflow in a Curved Compression Ramp (CCR) air intake apparatus (300) for ramjet and scramjet engines, the method comprising:
performing, by a Curved Compression Ramp (CCR) air intake apparatus (300), a flow shaping incoming high-speed airflow using a Curved Compression Ramp (CCR) assembly (301), the flow shaping comprising:
generating, by the CCR air intake apparatus (300), an initial oblique ramp shock wave at a leading edge (301c) of the CCR assembly (301) by generating a small flow deflection angle in the incoming high-speed airflow;
inducing, by the CCR air intake apparatus (300), a curved shock wave (303) through an interaction of the initial oblique ramp shock wave with a series of isentropic compression waves (305) along a curved fore segment (301a) of the CCR assembly (301); and
stabilizing and managing, by the CCR air intake apparatus (300), a compressed airflow in a planar aft segment (301b) tangentially aligned with an end of the curved fore segment (301a), wherein the planar aft segment (301b) is inclined at a pre-defined angle; and
directing, by the CCR air intake apparatus (300), the compressed airflow into an isolator (501) section with at least one of parallel walls and non-parallel walls downstream to a curved cowl assembly (307) being positioned opposite to the CCR assembly (301), the directing comprising:
aligning, by the CCR air intake apparatus (300), a leading-edge portion of an isolator (501) top-plate comprising a concavely curved inner surface of the curved cowl assembly (307) to guide the incoming high-speed airflow into the isolator (501) section; and
configuring, by the CCR air intake apparatus (300), a cowl lip (307a) of the curved cowl assembly (307) to satisfy a shock-on-lip condition at a pre-defined location relative to the leading edge (301c) of the CCR assembly (301), wherein the cowl lip (307a) is positioned relative to the leading edge (301c) of the CCR assembly (301), based on at least one design configuration, wherein the cowl lip (307a) is located in optimal position for intake stability and capture efficiency under both design and off-design conditions.

10. The method as claimed in claim 9, further comprising:
guiding, by the CCR air intake apparatus (300), the compressed airflow through an isolator (501) section downstream of the curved cowl assembly (307), the guiding comprising:
aligning, by the CCR air intake apparatus (300), parallel walls of the isolator (501) section with a pre-defined angle; and
controlling, by the CCR air intake apparatus (300), isolator back pressure within the isolator (501) section, the controlling comprising:
varying dynamically, by the CCR air intake apparatus (300), a fuel flow rate of a combustor coupled downstream of the isolator (501) section and manage pressure fluctuations induced by the combustor.

11. The method as claimed in claim 10, further comprising:
monitoring, by the CCR air intake apparatus (300), one or more parameters of the airflow throughout the CCR assembly (301), the cowl assembly (307), and the isolator (501) section using a sensor array, the monitoring comprising:
measuring, by the CCR air intake apparatus (300), one or more flow parameters comprising at least one of a pressure, a temperature, a Mach number, density gradient, parameters measured using one or more optical diagnostic techniques, and aero-dynamic flow parameters; and
transmitting, by the CCR air intake apparatus (300), sensor data to a feedback control system.

12. The method as claimed in claim 11, further comprising:
reflecting, by the CCR air intake apparatus (300), the curved shock wave (303) off the cowl lip (307a) as a terminal shock (309);
demarcating, by the CCR air intake apparatus (300), an external compression section from an internal compression section along a normal line (311) dropped from the cowl lip (307a) on a planar portion of the CCR assembly (301); and
controlling, by the CCR air intake apparatus (300), a Mach number distribution along the normal line (311), wherein the Mach number decreases monotonically from a maximum at the ramp surface to a minimum at the curved cowl assembly (307) due to a curved nature of an upstream shock wave.