Claims:We claim:
1. A high loaded three dimensional (3D) moving blade (100) for an axial steam turbine, comprising:
a set of subsonic blade profiles (1-9) having a suction curve and a pressure curve, wherein the set of subsonic blade profiles (1-9) is located between root section and shroud section;
a plurality of blades (1, 3, 5) configured with circumferentially grooved T roots (1r, 3r, 5r);
a plurality of guide blades (2; 4) interposed between the plurality of blades (1, 3;3, 5), in which the guide blades (2; 4) are configured with circumferentially grooved T roots (2r, 4r) at a shroud;
a passage between moving blade rows defines a path for a portion of steam flow; and
a plurality of blade platforms (1s-5s) determine the flow path passage through each moving blade.
2. The high loaded three dimensional (3D) moving blade (100) as claimed in claim 1, wherein the moving blade (100) includes a concave surface (10), a convex surface (11), a trailing edge (16) and a leading edge (15), wherein height of the leading edge (15) is at range 40 mm to 73 mm and height of the trailing edge (16) is at range 41.6 mm to 78 mm.
3. The high loaded three dimensional (3D) moving blade (100) as claimed in claim 1or 2, wherein shape of moving blade is made up of smooth surface passing through optimized profile section at radial location (H) defined by the suction and pressure curves.
4. The high loaded three dimensional (3D) moving blade (100) as claimed in the claims 1-3, wherein the suction profile curve and the pressure profile curve are represented by specific determinations such as herein described.
5. The high loaded three dimensional (3D) moving blade (100) as claimed in the claims 1-4, wherein leading edge radius (Rle) and trailing edge radius (Rte) are located between a hub and a shroud, wherein the radius of leading edge (15) and trailing edge (16) are defined by following determinations:
Leading Edge Radius (Rle) = -0.0019x + 1.9463
Trailing Edge Radius (Rte) = -0.0017x + 1.0356
6. The high loaded three dimensional (3D) moving blade (100) as claimed in the claims 1-5, wherein each blade profile from the set of subsonic blade profiles (1-9) includes multiple curves, which define the leading edge (15), suction side curve, pressure side curve and trailing edge (16) connected at a junction point with high order of smoothness.
7. The high loaded three dimensional (3D) moving blade (100) as claimed in the claims 1-6, wherein the moving blade (100) is mounted in a rotor groove which is coupled at a root and axially positioned between adjacent blade rows.
8. The high loaded three dimensional (3D) moving blade (100) as claimed in the claims 1-7, wherein pressure and Mach number distribution, flow separation, channel width change, profile smoothness, profile loss, allowable stresses and manufacturability form aerodynamic and structural parameters that influence the shape of blade profile section.
9. The high loaded three dimensional (3D) moving blade (100) as claimed in the claims 1-8, wherein shape of the blade (100) determines the aerodynamic characteristics and the plurality of blades (1, 3, 5) arranged circumferentially determines the characteristic of blade rows.
10. The high loaded three dimensional (3D) moving blade (100) as claimed in the claims 1-9, wherein the aerodynamic performance parameters include profile loss, profile loss coefficient, flow deflection and surface Mach number distribution. , Description:[001] The present invention relates to a three dimensional (3D) moving blades for axial steam turbine, which are required to convert thermal energy of main steam in to mechanical energy with high loading. In particular, to the 3D blades for subsonic flow, consisting of 3D aerofoils, root platform and integral shroud. The blades are capable to meet the requirement of mechanical stresses arising out of energy conversion of high enthalpy entry steam, wherein the blades to withstand the static and dynamic stresses caused by the increased blade loading and due to centrifuging action.
BACKGROUND OF THE INVENTION
[002] Generally, a high pressure (HP) or intermediate pressure (IP) steam turbine moving blades mounted on rotor in a circumferential groove projected outward in the flow path. The moving blades are arranged in alternating rows so that the flow of steam guided by previous blade row enters the moving row of blades at the correct angle. Thus, steam properties such as temperature, pressure and velocity changes as the steam expands through the blade path. It converts the thermal energy to mechanical energy and rotates the rotor. The moving blades are the most important component of the turbine in determining the turbine efficiency and consequently the heat rate of the power plant.
[003] Accordingly, the steam turbine requires to operate with high efficiency and reliability with reduced costs. In particular, in the steam turbine, it is desirable to reduce a number of stages and reduce the number of blades in each row for high pressure and intermediate pressure zone to reduce the overall cost.
[004] The unit cost and component length while maintaining the efficiency level can be attempted either by reducing number of stages or reducing the number of blades per rows. The number of stages and size of the turbine is limited by heat drop per stage. In order to reduce the number of stages and maintain the same overall power generation across the turbine, high stage aerodynamic loading (i.e. heat drop across each stage as the flow passes through the turbine) is essentially required. Unfortunately, as the stage aerodynamic loading increases the flow over the aerofoil Surface tends to Separate causing aerodynamic losses.
[005] In accordance with suitable modification in the blade, which allows for higher flow turning and at the same time maintaining the efficiency to acceptable levels through proper optimization permits to increase the heat drop per stage and hence overall heat drop can be achieved with fewer number of stages. There by this technique lead to a significant reduction in overall length and number of blade. Designing the cascade with higher flow turning and area variation suitably from inlet to outlet helps in suppressing flow separation, which is generally the case for highly loaded turbine. Typically increasing the stage loading by 10% per stage will decrease number of stages by 10% approximately. Reduction in number of blades per row also improve the blade loading by 5-8% (approximately). The conventional high pressure (HP) or intermediate pressure (IP) steam turbine blade, which allow expanding of the working fluid are limited to 20-30 kJ/kg of heat drop in order to keep the acceptable efficiency level.
[006] These turbine blades with higher blade loading are subjected to increased steady and dynamic stress levels than the conventional blades. The centrifugal stress is the mean stress at the operating speed of the turbine, and the alternating stress in the blades as the results of unsteady forces that exist in the turbine. The magnitude to dynamic loads also increases as these blades are suitable for higher diameter and also due to high flow deflections than the conventional blades. Further, there is a higher pressure & density gradient in these sections than the conventional blades, which further alleviate the stress level.
[007] The flow turning, blade chord, inlet and outlet blade angles, leading edge & trailing edge radius, maximum thickness of the profile, location of maximum thickness of the profile, blade height, blade lean, mean diameter, operating speed and aerodynamic conditions are the important factors that influence the aerodynamic and mechanical design of the blade. Due to higher stage loading, extremely complex flow field in the blade passage, losses at root & top region are inherently higher, therefore, requires a precisely defined profile for optimal performance with minimal losses. Damping and proper Stimulus ratio are the factors which must also be considered in the mechanical design of the blade. These mechanical and dynamic behavior of the blades, as well as others, such as aero-thermodynamic properties or material selection, all influence the optimum design of blade shape.
[008] The patent search has been carried out on this subject, but the complete information related to this invention is not directly available. The following patent documents (US 6,579,066 B1, WO2005040559 A1, DE102010053798A1, and US 7,175,393 B2). The prior art documents relate to High Pressure and Intermediate pressure steam turbine design that uses modular principles and also uses the standardized profiles which are pre-engineered and well evaluated through cascade testing, CFD and FEA at design and off-design condition for development of blade geometry to the extent possible.
[009] In accordance with the prior art documents are different from the present invention. The present invention relates to high and medium pressure turbine moving blade comprises of subsonic blade profiles capable of carrying higher heat drop than conventional turbine blade without scarifying the efficiency whereas the prior art is related mainly lower heat drop per stage and also founds application mainly in gas turbine and axial compressor. Also, the prior art blades are much less efficient if operated with higher heat drop per stage.
[0010] Fig. 1 illustrates outlook of a turbine bucket of the prior art reference, US 6,579,066 B1, assigned to Mitsubishi Hitachi Power Systems Ltd. The prior art reference shows a turbine bucket for at the low pressure last stage of a steam turbine with the bucket is formed by twisted sectional configuration from the blade root portion to a blade tip side. The blade Sections having +0.3 mm tolerance from respective points defining blade Section configurations. These blades are suitable for supersonic flow regions and not for subsonic flow regions, whereas the present patent is related to high and intermediate pressure turbine moving blade where the flow is mainly in subsonic region.
[0011] Accordingly, the prior art is related to transonic profiles for low pressure turbine blade. The transonic profiles mentioned which is used to develop 3D low pressure turbine blades is suitable for low pressure blading with low back pressure, whereas present invention refers to high pressure and or medium pressure moving turbine blade consists of optimized subsonic profiles.
[0012] Fig. 2 illustrates high lift rotor and stator blades with multiple adjacent aerofoils cross-section of prior art reference, WO2005040559 A1, assigned to “Paolo Pietricola”. The prior art reference describes a plurality of rotor blades, which is constituted by a main fin and or at least by second fin placed nearby the trailing edge of the main fin and a secondary fin located close to upper and or lower surface of the main fin, whereas the present invention consists of no such type of fins.
[0013] Fig. 3 illustrates rotor row with hybrid profile shape in a turbomachine of prior art reference, DE102010053798A1, assigned to Rolls-Royce Deutschland Ltd and Co KG. The prior art reference describes rotor/stator blade of a turbomachine with hybrid profile shape, where the distribution of passage width with minimum in the central

region. The flow in blade rows aerodynamically highly loaded but suffer from separation of the boundary layer flow on the blade profile whereas the present invention is free from such separation up to sufficiently high loading.
[0014] Fig. 4 illustrates aerofoil for an axial flow path turbo machine for the prior art reference, US 7,175,393 B2, assigned to Bharat Heavy Electricals Ltd. The prior art describes Mach number distribution for the hub profile section. The suction and Pressure surface Mach number distribution are intersection very earlier from the trailing edge which will results into high separation and secondary losses. In the present invention the profile is optimized to minimize for profile and secondary losses.
[0015] In accordance with the above mentioned prior art references 1 and 4 geometry is in Cartesian co-ordinates in terms of turbine bucket at various span location, whereas the present invention the 3D blade geometry made up of smoothly joined surface between with suction, pressure, leading and trailing edge curve and in form of 5th order polynomials and parameterized. In the prior art reference 2 and 3 geometry is not defined neither in terms of coordinates nor in terms of parameterized form.
[0016] In the conventional high and intermediate pressure profiles are not allowing to reduce the number of stages and hence size of the turbine efficiently, while operated at same rotor radius & higher stage loading whereas the present invention is permit to reduce the number of stages by 30 to 60% depends upon the rating of the steam turbine, without compromising much efficiency.
[0017] The information disclosed in this background of the disclosure section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
OBJECTS OF THE INVENTION
[0018] The principal object of the present invention is to provide various types of 3D blades for axial steam turbine especially for high and medium pressure turbine.
[0019] Another object of the present invention is to provide high or intermediate pressure turbine moving blades.
[0020] Yet another object of the present invention is to convert the total thermal energy required for power generation in fewer blades from the steam and to sustain the increased mechanical loads arises from the increased stage loading.
[0021] Yet another object of the invention to improve the power density across the stages of loading.
[0022] Further object of the present invention is to reduce the number of stages by 30 to 60% depends upon the rating of the steam turbine, without compromising the efficiency.
[0023] These and other objects and advantages of the present subject matter will be apparent to a person skilled in the art after consideration of the following detailed description taken into consideration with accompanying drawings in which preferred embodiments of the present subject matter are illustrated.
SUMMARY OF THE INVENTION
[0024] One or more drawbacks are overcome through the processes claimed in the present invention along with the additional advantages. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be a part of the claimed disclosure.
[0025] The present subject matter relates to a high loaded three dimensional (3D) moving blade for an axial steam turbine. The moving blade comprises a set of subsonic blade profiles having a suction curve and a pressure curve, wherein the set of the multiple subsonic blade profiles is located between root section and shroud section. Further, the moving blade includes a plurality of blades that is configured with circumferentially grooved T roots, a plurality of guide blades that is interposed between the plurality of blades and configured with circumferentially grooved T roots at a shroud, a passage between moving blade rows defines a path for a portion of steam flow, and a plurality of blade platforms that determine the flow path passage through each moving blade.
[0026] Accordingly, each blade profile of the set of subsonic blade profiles includes a plurality of curves, which defines the leading edge, suction side curve, pressure side curve and trailing edge connected at a junction point with high order of smoothness. A set of profile sections of blade profiles at H distances is joined smoothly with one another to form the complete moving blade of high and intermediate pressure turbine. The moving blade is stated with improved stage loading by 36% over the conventional one with scarifying the overall efficiency of the turbine.
[0027] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, 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 or methods or structure in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
FIG. 1 illustrates outlook of turbine bucket with high pressure turbine rotating blade of prior art;
FIG. 2 illustrates view of high lift rotor and stator blades with multiple adjacent aerofoils cross-section of prior art;
FIG. 3 illustrates view of rotor row with hybrid profile shape for use in a turbomachine of prior art;
FIG. 4 illustrates view of aerofoil for an axial flow turbo machine of prior art;
FIG. 5 illustrates view of Meridional flow path of high or intermediate pressure turbine, in accordance with a present subject matter;
FIG. 6 illustrates cross section view of moving blade, in accordance with a present subject matter;
FIG. 7 illustrates prospective view of three-dimensional (3D) last stage moving blade for high or intermediate pressure turbine, in accordance with a present subject matter;
FIG. 8 illustrates graphical representation of Mach number distribution across the blade channel at a hub section; in accordance with a present subject matter;
FIG. 9 illustrates graphical representation of Mach number distribution across the blade channel at a tip section; in accordance with a present subject matter;
FIG. 10 illustrates graphical representation of local lean for a moving blade; in accordance with a present subject matter;
FIG. 11 illustrates graphical representation of finite element stress analysis result for a moving blade; in accordance with a present subject matter;
FIG. 12 illustrates diagrammatic view of finite element stress analysis result for a moving blade; in accordance with a present subject matter; and
FIG. 13 illustrates diagrammatic view of moving blade deformation; in accordance with a present subject matter.
[0029] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0030] While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.
[0031] The terms “comprises”, “comprising”, or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusion, such that a device, system, assembly that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such system, or assembly, or device. In other words, one or more elements in a system or device proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or device.
[0032] The present subject matter relates generally to the field of aerodynamics and, more specifically a high and medium pressure turbine moving blade shape with improved stage loading. The blade shape made up of smooth surface passing through optimized profile section at radial location H defined by suction and pressure curves. The moving blade comprises a set of subsonic blade profiles where each blade profile is made up with suction and pressure curves defined in accordance with specific determinations, and leading and trailing edge radius defined by another specific determination are optimized profile for improved blade loading for subsonic flow up to Mach number 0.8 within high and intermediate pressure turbine applications. Each blade profile includes a plurality of curves, which defines the leading edge, suction side curve, pressure side curve and trailing edge connected at the junction point with high order of smoothness. The profile sections of blade profiles at H distances are joined with one another to form the complete moving blade of high and intermediate pressure turbine. The moving blade is stated having improved stage loading by 36% over the conventional one with scarifying the overall efficiency of the turbine.
[0033] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0034] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0035] Referring to FIG. 5 illustrates view of Meridional flow path of high or intermediate pressure turbine, in accordance with a present subject matter. The Meridional flow path of high or intermediate pressure turbine has a plurality of blades (1, 3, 5) with circumferentially grooved T roots (1r, 3r, 5r) and a plurality of guide blades (2, 4) that is interposed between the plurality of blades (1, 3, 5) and circumferentially grooved T root (2r, 4r) at a shroud. A plurality of moving blades is mounted in the rotor groove which are coupled at the root and axially positioned between adjacent blade rows. A passage is formed between the moving blades row defines the path for a portion of steam flow, and a blade platform (1s, 3s, 5s) determines the flow path passage through each moving blade.
[0036] Referring to FIG. 6 illustrates cross section view of the moving blade, in accordance with a present subject matter. The moving blade 100 comprises a profile section of blade profiles 1-9 having pressure curve, leading edge curve, trailing edge curve and suction curve. Pressure and Mach number distribution, flow separation, channel width change, profile smoothness, profile loss, allowable stresses and manufacturability are some of the aerodynamic and structural parameters that influence final shape of the blade profile section.
[0037] Accordingly, the moving blade comprises suction profile curve and pressure profile curves is represented by below determinations:
X and Y coordinated of pressure curve is related with the following determinations:
X_ps= Ax_chord* [0.178156839*a_ps*((1-t)^5)*(t^1)+
5.25562674*a_ps*((1-t)^4)*(t^2)+
8.976980566*a_ps*((1-t)^3)*(t^3)+
9.976782965*a_ps*((1-t)^2)*(t^4)+
5.433783579*a_ps*((1-t)^1)*(t^5)+
0.986947316*((1-t)^0)*(t^6)] ……..1
Y_ps= 1.5294* Ax_chord* [[ 1.439460359*a_c*((1-t2)^5)*(t2^1)+
7.925888815*a_c*((1-t2)^4)*(t2^2)+
6.779747953*a_c*((1-t2)^3)*(t2^3)+
12.00504572*a_c*((1-t2)^2)*(t2^4)+
4.842849219*a_c*((1-t2)^1)*(t2^5)+
((1-t)^0)*(t2^6)]/[8.5278*b_c*((1-t2)^5)*(t2^1)+
65.646*b_c*((1-t2)^4)*(t2^2)+
25.678*b_c*((1-t2)^3)*(t2^3)-
78.7755*b_c*((1-t2)^2)*(t2^4)-
24.9936*b_c*((1-t2)^1)*(t2^5)-
11.9607*((1-t2)^0)*(t2^6)]] * b_ps* ((1-t)^5)*(t^1)
-8.9211*b_ps*((1-t)^4)*(t^2)
+0.8708*b_ps*((1-t)^3)*(t^3)-
13.8709*b_ps*((1-t)^2)*(t^4)-
8.9542*b_ps*((1-t)^1)*(t^5) –
11.9039*((1-t)^0)*(t^6) ………2

X and Y coordinated of suction curve is related with the following determinations:
X_ss = Ax_chord * [-0.107323397*a_ss*((1-t)^5)*(t^1)+
3.353856149*a_ss*((1-t)^4)*(t^2)+
13.77316925*a_ss*((1-t)^3)*(t^3)+
11.62670132*a_ss*((1-t)^2)*(t^4)+
5.545042167*a_ss*((1-t)^1)*(t^5)+
1.00349761*((1-t)^0)*(t^6)) ] ………….. 3

Y_ss = 5.7118*Ax_chord*[[ 2.441088586*a_c*((1-t2)^5)*(t2^1)+
4.845497325*a_c*((1-t2)^4)*(t2^2)+
6.183327667*a_c*((1-t2)^3)*(t2^3)+
13.91159262*a_c*((1-t2)^2)*(t2^4)+
4.781763853*a_c*((1-t2)^1)*(t2^5)+
((1-t)^0)*(t2^6)] / [17.6478*b_c*((1-t2)^5)*(t2^1)+
13.545*b_c*((1-t2)^4)*(t2^2)+
126.49*b_c*((1-t2)^3)*(t2^3)-
144.5235*b_c*((1-t2)^2)*(t2^4)-
22.9044*b_c*((1-t2)^1)*(t2^5)-
12.0034*((1-t2)^0)*(t2^6)]]*b_ss*((1-t)^5)*(t^1)+
1.9983*b_ss*((1-t)^4)*(t^2)
+19.3638*b_ss*((1-t)^3)*(t^3)-
1.6054*b_ss*((1-t)^2)*(t^4)+
2.1553*b_ss*((1-t)^1)*(t^5) –
11.8049*((1-t)^0)*(t^6) ………….4
[0038] Accordingly, the high or intermediate pressure turbine moving blade comprises shape parameters of blade profile defined in accordance with Table 1.
Parameters
a_ps a_ps a_ss b_ss t2
Profile 1 1.041034 1.286023 1.079862 1.198876 0.005
Profile 2 1.03133 1.240651 1.068475 1.15681275 0.005
Profile 3 1.021625 1.195279 1.057087 1.1147495 0.005
Profile 4 1.011921 1.149906 1.0457 1.07268625 0.005
Profile 5 1.002216 1.104534 1.034312 1.030623 0.005
Profile 6 0.992512 1.059162 1.022925 0.98855975 0.005
Profile 7 0.982807 1.01379 1.011537 0.9464965 0.005
Profile 8 0.973103 0.968417 1.00015 0.90443325 0.005
Profile 9 0.963398 0.923045 0.988762 0.86237 0.005
Table 1
[0039] Referring to FIG. 7 illustrates prospective view of three-dimensional (3D) moving blade for high or intermediate pressure turbine, in accordance with a present subject matter. The moving blade 100 is designed with a plurality of blade profiles (1-9) located between a root section and a shroud section and connected to define the blade shape. The shape of blade determines the aerodynamic characteristic of the blade and a plurality of blades when arranged circumferentially determines the characteristic of blade rows. The moving blade 100 includes a blade portion that comprises of a concave surface 10, a convex surface 11, a trailing edge 16 and a leading edge 15, wherein the steam flows generally from the leading edge 15 to the trailing edge 16. The concave surface 10 and convex surface 11 are connected at the leading edge 15 and the trailing edge 16, and extend radially between a rotor blade root and a rotor blade tip. A blade chord distance L is a distance measured from the leading edge 1 to the trailing edge 3 at any point along a radial length H of the moving blade 100.
[0040] The leading edge 15 and the trailing edge 16 are defined by the determinations 5 and 6. The trailing edge radius (Rte) confirms the strength and vibration requirement criteria.
Leading Edge Radius (Rle):
Rle = -0.0019x + 1.9463 …… 5
Trailing Edge Radius (Rte):
Rte = -0.0017x + 1.0356 ……6
[0041] The pressure surface 2 and the suction surface 4 are determined by the stated determinations 1 to 6 in order to maintain the smooth surface along the radial length H of moving blade. Accordingly, height of the leading edge 15 is in the range of 40 mm to 73 mm, and height of the trailing edge 16 is in the range of 41.6 mm to 78 mm. Although the leading and trailing edge height described herein 56 mm and 59.6 mm respectively.
[0042] Referring to Fig. 8 and 9 illustrate graphical representation of Mach number distribution across the blade channel at hub and tip sections, respectively. Two dimensional (2D) and three dimensional (3D) aero foils are designed for aerodynamic performance using streamline curvature code. Therefore, optimization of the blade loading is done with genetic algorithm coupled to Computational Fluid Dynamics (CFD). The aerodynamic performance parameters such as profile loss, profile loss coefficient, flow deflection, surface Mach number distribution are evaluated during 2D cascade analysis.
[0043] Referring to Fig. 10 illustrates graphical representation of local lean for a moving blade; in accordance with a present subject matter. The local lean is defined as the local angle made by the line passing through centre of gravity of two adjacent profile with the radial line passing through the centre of gravity of hub profile and angle placement of profiles centre of gravity in radial direction. In addition, the use of local lean an additional X and Y shift in the centre of gravity of profile located from the section 2 to section 7 for with respect to profile located at section 1 is provided to take the advantage in static and dynamic stress induced during the operation. This local lean and shift in profile centre of gravity defines the 3D shape of the blade.
[0044] In accordance with an embodiment of the present subject matter relates to the vibration characteristic that is fixed and any change in shape can change the vibration characteristic in undesired way after manufacturing the blade. A profile chord of moving blade is important criteria to ensure structural integrity during operation. The moving blade 100 is provided with the high back pressure staged herein having optimized chord for wide range of operation, thereby maintaining the intended performance of blade, and modifying the shape of blade may be subjected to determine the modified behavior through computer analysis.
[0045] Accordingly, the analysis determine the optimum amount of mass required to achieve level of dynamic stress. The modified blade is provided by removing the mass increase the natural frequency of blade and adding mass increases the natural frequency of blade.
[0046] Referring to Fig. 11-13 illustrate dynamic stresses of the blade to be characterized by Campbell and Goodman diagram. The strength and vibration characteristic for low pressure turbine moving blade 100 with high back pressure are more difficult than the conventional low pressure blading. Design for low pressure turbine moving blades for high back pressure tends towards thicker blade than the conventional low pressure blading. Thicker blade shifts generally shifts the natural frequency of the blade 100 to lower side, which is ensured through vibration analysis and dynamic stress evaluation.
[0047] In accordance with the present subject matter provides many advantages over conventional high and intermediate pressure blading, which includes improved stage loading by 30-40% greater than the conventional without scarifying the efficiency. Further, this improvement permits to reduce the number of stages and in-turn overall size of the turbine for the same power rating of the turbine. In addition, the tangent and curvature continuity has to be ensured for all the curve during manufacturing to maintain the surface continuity, the local lean of the moving blade eliminates secondary losses in the hub area and also reduces the pressure gradient in radial direction.
Reference Numerals
Fig. 5 and 6
Moving Blade of Turbine-101
Blade Root-102
Shroud-103
Suction side curve-201
Pressure side curve-202
Leading Edge Radius-Rle
Trailing Edge Radius-Rte
Fig. 11
Bending Stress at LE-301
Normal Stress-302
Bending Stress-303
Bending Stress at TE-304
[0048] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances, where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”
[0049] It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of “comprising” or “including” also contemplates embodiments that “consist essentially of” or “consist of” the recited feature.
[0050] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.