1. A rotor for use in a screw compressor comprising of: a male rotor (101) and a female rotor (102), each having a helical profile and being housed within a compressor housing; wherein gas is drawn into an inlet, compressed between the rotor profiles, and discharged through an outlet, characterized by a biomimetic micro-textured surface (303) applied to the rotor surfaces; the micro-textures (303) comprising riblet structures (103) modelled after shark skin denticles; aligned with the direction of gas flow and fabricated using laser micromachining; additive manufacturing or nano-imprinting to reduce boundary layer drag and enhance flow dynamics within the compression chamber.

2. The rotor for use in a screw compressor as claimed in claim 1, wherein the riblet structures are V-shaped, U-shaped, or trapezoidal in cross-section.

3. The rotor for use in a screw compressor as claimed in claim 1, wherein the riblet structures are formed integrally during rotor fabrication using additive manufacturing.

4. The rotor for use in a screw compressor as claimed in claim 1, wherein the riblet structures are applied to the rotor surface using laser micromachining or nano-imprinting.

5. A screw compressor system comprising: a compressor housing; a male rotor (101) and a female rotor (102) positioned within the housing and configured to intermesh; an inlet port for admitting uncompressed gas; an outlet port for discharging compressed gas (306); bearings and seals for supporting and enclosing the rotors; characterized by the rotor surfaces comprising biomimetic micro-textured surfaces (303) formed with riblet structures (103) aligned with gas flow; the micro-textures (303) reducing boundary layer drag and enhancing internal flow dynamics.

6. The screw compressor system as claimed in claim 5, wherein the micro-textured rotor surfaces (303) are adapted for use in oil-injected or oil-free compressor configurations.

7. The screw compressor system as claimed in claim 5, wherein the riblet (103) dimensions and orientations are customized based on rotor speed, pressure conditions, and gas type.

8. A method for manufacturing a rotor for a screw compressor, the method comprising: forming a rotor with a helical profile; generating riblet structures (103) inspired by shark skin on the surface of the rotor; characterized by aligning the riblet structures (103) with gas flow direction and forming the riblets (103) using laser micromachining, additive manufacturing, or nano-imprinting to reduce aerodynamic drag and optimize boundary layer behaviour.

9. The method for manufacturing a rotor for a screw compressor as claimed in claim 8, wherein the riblet structures (103) are integrated during rotor fabrication using additive manufacturing.

10. The method for manufacturing a rotor for a screw compressor as claimed in claim 8, wherein the riblet structures (103) are applied post-fabrication using laser micromachining or nano-imprinting techniques.

Description:A) TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates to the field of screw compressors. The present invention more particularly relates to an innovative surface modification of screw rotors using biomimetic micro-textures inspired by shark skin to reduce aerodynamic drag and enhance energy efficiency.

B) BACKGROUND OF THE INVENTION
[0002] Screw compressors are widely used in industrial settings for the compression of gases due to their robustness, reliability, and capacity to deliver continuous, oil-free or oil-injected compression. These compressors typically comprise intermeshing helical male and female rotors enclosed within a tightly sealed housing. During operation, gas is drawn in through an inlet, trapped between the rotor lobes and the casing, and progressively compressed as the volume of these trapped pockets decreases along the rotor length. The compressed gas is then discharged through an outlet.
[0003] One of the primary challenges in screw compressor operation is the significant aerodynamic drag encountered by the rotating rotor surfaces as they interact with high-velocity, high-pressure gases. This drag not only results in energy losses but also contributes to inefficiencies in flow dynamics, increasing power consumption and operational costs. Additionally, turbulence and flow separation around the rotor surfaces can lead to reduced volumetric efficiency and thermal instability.
[0004] Efforts to address such inefficiencies have traditionally focused on improving rotor geometry, enhancing coatings, or modifying flow control components. However, these methods often provide incremental gains and may not effectively tackle the root cause of drag generation associated with turbulent boundary layer interactions along the rotor surfaces.
[0005] Alongside, biomimicry has emerged as a promising design strategy in engineering. Notably, the micro-textures found on shark skin, known as riblets, have been shown to reduce drag by controlling the turbulent boundary layer flow. These structures have been successfully applied to aerodynamic and hydrodynamic surfaces such as aircraft fuselages and ship hulls, leading to measurable efficiency improvements.
[0006] However, the direct application of these shark skin-inspired technologies to screw compressors has not been previously achieved due to fundamental differences in geometry, scale, and flow conditions. Shark skin technologies are typically designed for relatively flat or gently curved surfaces experiencing unidirectional flow. In contrast, screw rotors feature complex helical geometries and are subject to multi-directional, turbulent gas flows within confined high-pressure chambers.
[0007] Moreover, existing riblet-based drag reduction approaches are optimized for large-scale systems and are not readily scalable or adaptable to the small, intricate, and high-tolerance surfaces of screw rotors. The lack of compatibility with current rotor manufacturing processes, and the absence of multi-functional benefits such as wear resistance or anti-fouling capability, further limit their applicability.
[0008] Accordingly, there is a need for a novel surface engineering solution that is specifically tailored for screw compressor applications. Such a solution must effectively reduce drag under multi-directional, turbulent flow conditions, be compatible with existing rotor designs and manufacturing processes, and offer additional performance benefits including enhanced durability, maintenance reduction, and thermal regulation.
[0009] The above-mentioned shortcomings, disadvantages and problems are addressed herein, as detailed below.

C) OBJECTS OF THE INVENTIONS
[0010] The primary object of the present invention is to reduce aerodynamic drag on the surfaces of screw compressor rotors by implementing biomimetic micro-textured structures inspired by shark skin. This drag reduction aims to improve gas flow efficiency and significantly lower the energy consumption associated with gas compression operations.
[0011] Another object of the present invention is to enhance the energy efficiency of screw compressors by minimizing power losses caused by turbulent boundary layer interactions along the rotor surfaces. By optimizing the surface characteristics, the invention contributes to sustainable and cost-effective industrial operations.
[0012] Yet another object of the present invention is to improve the flow dynamics within the compression chamber of screw compressors. The micro-textured surfaces are designed to streamline gas flow, reduce turbulence and flow separation, and thereby increase the volumetric efficiency of the compression cycle.
[0013] Yet another object of the present invention to incorporate multi-functional surface properties into the rotors. The micro-textures not only reduce drag but also exhibit anti-fouling characteristics, preventing the accumulation of deposits and contaminants on the rotor surfaces. This reduces the need for frequent maintenance and prolongs the operational lifespan of the compressor.
[0014] Yet another object of the present invention is to enhance the durability and thermal stability of screw compressor rotors. The micro-textures are designed to withstand high-pressure, high-speed, and abrasive operating environments, while also facilitating better heat dissipation through improved gas flow characteristics, thereby minimizing thermal stress on the rotors.
[0015] Yet another object of the present invention is to enable seamless integration of the invention into existing manufacturing workflows and compressor designs. The micro-textures can be applied using advanced, scalable techniques such as laser micromachining, additive manufacturing, or nano-imprinting, ensuring compatibility with current production methods without compromising rotor balance or performance.
[0016] A still further object of the invention is to provide a versatile and scalable solution that can be employed across a broad spectrum of screw compressor types and configurations. The micro-textured surfaces are customizable to suit different rotor geometries and gas flow profiles, making the invention suitable for varied operational requirements and deployment environments.
[0017] These and other objects and advantages of the embodiments herein will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.

D) SUMMARY OF THE INVENTION
[0018] The various embodiments of the present invention disclose a screw compressor rotor surface design that incorporates micro-textures inspired by shark skin riblets. These micro-textures are engineered to align with the helical geometry of male and female screw rotors and are designed to minimize boundary layer drag and improve aerodynamic flow characteristics within the compression chamber.
The reference numerals used in the drawings and the invention description herein below are as follows:
Reference Numeral Description
101 Male Rotor
102 Female Rotor
103 Riblet(s) / riblet structures
201 Low Pressure side
202 High Pressure Side
203 Radial Clearance
204 Interlobe Clearance
205 Discharge axial clearance
301 Start gas intake
302 Gas trapped in rotor pockets
303 Mirco-textured surfaces reduce drag
304 Reduced turbulence and improved flow dynamics
305 Lower power consumption and energy efficiency
306 Compressed gas discharge
307 End

[0019] The primary embodiment of the present invention the screw rotors are manufactured with a series of micro-scale riblet structures that are aligned in the direction of gas flow. These riblets (103) can take various cross-sectional shapes such as V-shaped, U-shaped, or trapezoidal, and are precisely dimensioned to interact optimally with the turbulent boundary layer that develops during compression.
[0020] According to another embodiment of the present invention involves integrating the micro-textures onto existing rotor surfaces using advanced manufacturing techniques, including laser micromachining, additive manufacturing, or nano-imprinting. These methods allow for the creation of high-resolution patterns without compromising the rotor’s structural integrity or balance.
[0021] According to yet another embodiment of the present invention, the micro-textures (303) are formed during the rotor fabrication process through additive manufacturing. This approach enables the riblets (103) to be an inherent part of the rotor body, reducing manufacturing steps and ensuring alignment with rotor geometry.
[0022] Yet another embodiment of the present invention provides for a layered or coated structure wherein a micro-textured surface (303) layer is deposited or bonded onto the rotor’s base material. This configuration provides flexibility in material selection and allows for additional performance attributes such as enhanced wear resistance or anti-fouling capability.
[0023] According to yet another embodiment of the present invention, the riblet (103) dimensions are dynamically optimized based on the specific operating conditions of the compressor, such as rotor speed, pressure differential, and gas type. Computational modeling and flow analysis tools may be employed to tailor the micro-texture (303) parameters accordingly.
[0024] Yet another embodiment of the present invention provides for configurations for both oil-injected and oil-free screw compressors, with micro-textures (303) adapted to the differing lubrication and cooling requirements of these systems. The riblet (103) orientation and placement may vary based on the intended direction of gas flow and thermal load distribution.
[0025] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
E) BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:
Fig. 1 illustrates visualization of Shark Skin-Inspired V-Shaped Riblets (103) (10 Microns Depth) on Male and Female Screw Compressor Rotors (101, 102) for Drag Reduction and Energy Efficiency.
Fig. 2 illustrates clearances in an Assembled Screw Compressor: Highlighting Radial clearance (203), interlobe clearance (204), and Discharge Axial clearance (205) in Relation to Low and High-Pressure Sides (201, 202).
Fig. 3 illustrates a flowchart of the complete process with micro-textured surfaces (303) to reduce drag.

F) DETAILED DESCRIPTION OF THE INVENTION
[0027] The present invention relates to a system and method for reducing drag in screw compressors using shark skin-inspired micro-textured rotor surfaces (303). The system comprises a pair of intermeshing / interlocking screw rotors i.e., male and female, enclosed within a compressor housing. Each rotor is equipped with micro-textured surfaces (303) formed of riblet (103) structures that follow the helical rotor profile. These micro-textures (303) are specifically adapted to manage turbulent, multi-directional gas flows during compression.
[0028] The riblet structures (103) on the rotor surfaces are aligned parallel to the gas flow path and are dimensioned based on fluid dynamic parameters such as Reynolds number and skin friction coefficient. The textures may take V-shaped, U-shaped, or trapezoidal forms and are manufactured using precision techniques such as laser micromachining, additive manufacturing, or nano-imprinting. These textures alter the structure of the turbulent boundary layer, leading to drag reduction and improved flow characteristics.
[0029] The system further includes standard components of a screw compressor such as the compressor housing, inlet and outlet ports, drive mechanism, bearings, and seals. The compressor housing provides the enclosure for rotor operation and channels the gas flow through the compression cycle. The inlet port allows the uncompressed gas to enter the rotor chamber, while the outlet port discharges the compressed gas (306).
[0030] The bearings support the rotors at either end, ensuring proper alignment and reducing mechanical losses due to friction. Seals are positioned around the rotor shafts to prevent leakage of compressed gas and maintain chamber integrity. A drive mechanism, which can be typically an electric motor provides rotational input to the male rotor (101), which in turn drives the female rotor (102) through intermeshing engagement.
[0031] Optionally, a cooling system may be integrated to manage heat generated during compression. The system may employ oil or water cooling, depending on whether the compressor is oil-injected or oil-free. In oil-injected systems, the micro-textures (303) are adapted to retain a thin oil film for lubrication, without sacrificing aerodynamic efficiency. In oil-free configurations, the riblets (103) are optimized to dissipate heat through enhanced flow dynamics.
[0032] The invention also provides a method for operating the screw compressor system comprising micro-textured (303) rotors. The method includes the steps of:
i. Receiving uncompressed gas through an inlet port.
ii. Trapping the gas within rotor pockets (302) as the rotors rotate.
iii. Compressing the gas by reducing the pocket volume along the rotor length.
iv. Reducing drag and turbulence via boundary-layer manipulation by the riblet (103) structures.
v. Discharging the compressed gas (306) through the outlet port.
vi. Regulating heat and wear through improved gas flow and optional cooling.
[0033] The method may further include dynamic adjustment or customization of riblet (103) geometries depending on the rotor speed, gas properties, and system pressure. Such customization ensures optimal drag reduction under varying operational conditions.
[0034] The system and method of the present invention maintain compatibility with existing compressor architectures, allowing for retrofit or new-build implementation. The rotors can be produced using conventional materials and machining tolerances, and the micro-textures (303) do not require significant design changes to housings or ancillary components.
[0035] The invention also encompasses configurations where the riblets (103) are embedded in a coating or layer bonded to the rotor substrate. This layer may offer enhanced anti-fouling or wear-resistant properties, and can be replaced or refurbished independently of the rotor body. Additionally, computational tools may be used to simulate and optimize the gas flow interaction with the riblet structures (103) before manufacturing.
[0036] In essence, the detailed description includes a comprehensive system integrating biomimetic micro-textured (303) rotors, housing, flow paths, sealing components, and thermal regulation subsystems. The method of operation focuses on improved aerodynamic behaviour during compression cycles to enhance efficiency, reduce power consumption, and extend component lifespan. , Claims:We Claim:
1. A rotor for use in a screw compressor comprising of:

a male rotor (101) and a female rotor (102), each having a helical profile and being housed within a compressor housing;

wherein gas is drawn into an inlet, compressed between the rotor profiles, and discharged through an outlet,

characterized by

a biomimetic micro-textured surface (303) applied to the rotor surfaces;

the micro-textures (303) comprising riblet structures (103) modelled after shark skin denticles;

aligned with the direction of gas flow and fabricated using laser micromachining;

additive manufacturing or nano-imprinting to reduce boundary layer drag and enhance flow dynamics within the compression chamber.

2. The rotor for use in a screw compressor as claimed in claim 1, wherein the riblet structures are V-shaped, U-shaped, or trapezoidal in cross-section.

3. The rotor for use in a screw compressor as claimed in claim 1, wherein the riblet structures are formed integrally during rotor fabrication using additive manufacturing.

4. The rotor for use in a screw compressor as claimed in claim 1, wherein the riblet structures are applied to the rotor surface using laser micromachining or nano-imprinting.

5. A screw compressor system comprising:
a compressor housing;

a male rotor (101) and a female rotor (102) positioned within the housing and configured to intermesh;
an inlet port for admitting uncompressed gas;
an outlet port for discharging compressed gas (306);
bearings and seals for supporting and enclosing the rotors;

characterized by

the rotor surfaces comprising biomimetic micro-textured surfaces (303) formed with riblet structures (103) aligned with gas flow;

the micro-textures (303) reducing boundary layer drag and enhancing internal flow dynamics.

6. The screw compressor system as claimed in claim 5, wherein the micro-textured rotor surfaces (303) are adapted for use in oil-injected or oil-free compressor configurations.

7. The screw compressor system as claimed in claim 5, wherein the riblet (103) dimensions and orientations are customized based on rotor speed, pressure conditions, and gas type.

8. A method for manufacturing a rotor for a screw compressor, the method comprising:

forming a rotor with a helical profile;
generating riblet structures (103) inspired by shark skin on the surface of the rotor;

characterized by

aligning the riblet structures (103) with gas flow direction and forming the riblets (103) using laser micromachining, additive manufacturing, or nano-imprinting to reduce aerodynamic drag and optimize boundary layer behaviour.

9. The method for manufacturing a rotor for a screw compressor as claimed in claim 8, wherein the riblet structures (103) are integrated during rotor fabrication using additive manufacturing.

10. The method for manufacturing a rotor for a screw compressor as claimed in claim 8, wherein the riblet structures (103) are applied post-fabrication using laser micromachining or nano-imprinting techniques.