Method and device for reducing aerodynamic torque of helicopter rotor wing type
By calculating the disturbance shape coordinates by parametric expressions and superimposing them onto the rotor airfoil, the problem of long-term optimization iteration in rotor airfoil design is solved. This achieves the reduction of rotor airfoil aerodynamic torque and the maintenance of lift and drag characteristics, thereby improving the helicopter's control load and flight performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-10
- Publication Date
- 2026-03-20
AI Technical Summary
In existing technologies, the optimization design of rotor airfoils to reduce torque requires long-term iterative optimization and computational analysis, and it is difficult to balance lift and drag characteristics, which affects the flight performance and safety of helicopters.
The coordinates of the disturbance shape are calculated using parametric expressions and superimposed onto the original rotor airfoil. Through local aerodynamic shape improvement and optimization, the aerodynamic torque is reduced while maintaining good lift and drag performance.
It effectively reduces the aerodynamic moment of the rotor airfoil without changing the main external parameters, thereby improving the helicopter's control load and flight performance and extending its service life.
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Figure CN121706643A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of helicopter rotor aerodynamics technology, and particularly relates to a method and apparatus for reducing the aerodynamic torque of a helicopter rotor airfoil. Background Technology
[0002] The rotor airfoil is the two-dimensional cross-sectional shape of a helicopter rotor blade, serving as a prerequisite and input for analyzing and evaluating its aerodynamic performance, aerodynamic loads, dynamics, and flight mechanics. The performance of the rotor airfoil significantly impacts the helicopter's payload, range, speed, and other flight performance characteristics. The development of high-performance rotor airfoils has always been a key technology in the ongoing research of helicopter aerodynamics. The aerodynamic performance of a rotor airfoil mainly includes its lift, drag, and moment characteristics under different flight conditions. The lift and drag of the rotor airfoil primarily affect the helicopter's aerodynamic efficiency and flight maneuverability. The aerodynamic moment of the airfoil has a significant impact on the helicopter's aerodynamic performance, aerodynamic loads, and dynamic characteristics. Excessively high aerodynamic moments can cause torsional deformation of the helicopter rotor blades, affecting its aerodynamic performance and dynamic stability. Simultaneously, the airfoil aerodynamic moment is also a major source of control loads in the helicopter rotor system; excessively high aerodynamic moments can lead to severe control load problems, shorten the helicopter's fatigue life, and affect flight safety. Therefore, consistent rotor airfoil aerodynamic moment is a key factor that needs to be considered in the aerodynamic design of helicopters. In recent years, with the increasing demand for large-tonnage, high-speed helicopters, the blade deformation and control load problems caused by the rotor airfoil moment coefficient have a more significant impact. Therefore, developing an optimized design method suitable for reducing the aerodynamic forces of helicopter rotor airfoils is of great significance for the research and development of advanced helicopters.
[0003] Currently, there are generally two technical approaches to optimizing rotor airfoil design to reduce moment: one is to use aerodynamic moment as a constraint in the early stages of airfoil design, obtaining an airfoil shape that balances lift, drag, and moment through multi-objective optimization; the other is to modify the shape of an existing airfoil by adjusting its maximum camber, trailing edge angle, and trailing edge length to reduce airfoil moment. However, due to the complexity of the rotor airfoil's operating environment and the inherent contradictions between multiple design objectives, the first approach generally requires several years of continuous optimization iteration, computational analysis, and experimental verification to obtain an airfoil design with excellent lift, drag, and moment performance. While the second approach can effectively reduce airfoil aerodynamic moment in a short time, it generally causes a loss of other aerodynamic properties such as lift and drag. For example, while trailing edge adjustments reduce moment, they also reduce maximum lift. Summary of the Invention
[0004] To address the issues of existing technologies requiring lengthy and continuous optimization iterations, computational analysis, and verification for rotor airfoil torque reduction, and the difficulty in simultaneously considering airfoil lift and drag characteristics, this invention proposes a method and apparatus for reducing the aerodynamic torque of helicopter rotor airfoils. By parametrically improving and optimizing the local aerodynamic shape of existing airfoils, without the need for costly iterative optimization calculations or alteration of the airfoil's main shape parameters, it achieves effective reduction of airfoil aerodynamic torque while maintaining good lift and drag aerodynamic performance. The technical solution is as follows:
[0005] Firstly, a method for reducing the aerodynamic moment of a helicopter rotor airfoil is provided. The method uses parametric expressions to calculate the coordinates of the disturbed shape, and then superimposes the calculated coordinates of the disturbed shape onto the original rotor airfoil to obtain the improved airfoil aerodynamic shape, thereby reducing the aerodynamic moment.
[0006] Optionally, the method specifically includes:
[0007] A parametric expression for improving and optimizing the local shape of a rotor airfoil is established. This parametric expression consists of a cosine function and a polynomial function, which can achieve a continuous and smooth transition of the rotor airfoil's aerodynamic shape.
[0008] The updated dimensionless coordinates of the upper and lower surface rotor airfoils are obtained based on the parametric expressions.
[0009] Optionally, the parameterized expression for optimizing the local shape of the rotor airfoil is specifically established as follows:
[0010] (1) Obtain the chord length C of the original rotor airfoil and the coordinate values of the upper and lower surfaces of the airfoil; the chord length refers to the length of the chord line from the leading edge point to the trailing edge point of the airfoil. The airfoil coordinates take the leading edge point of the airfoil as the origin of the coordinates. The X direction of the coordinates is the same as the chord line direction, and the Y direction is perpendicular to the chord direction.
[0011] (2) Using the rotor airfoil chord length C as a reference, dimensionless processing is performed on the coordinates of the upper and lower surfaces of the airfoil to obtain the dimensionless abscissa of the upper surface. and ordinate and the dimensionless abscissa of the lower surface and ordinate
[0012] (3) Establish a parametric expression for improving and optimizing the local shape of the rotor airfoil. This parametric expression consists of a cosine function and a polynomial function, which can achieve a continuous and smooth transition of the rotor airfoil's aerodynamic shape. The parametric expression is as follows:
[0013]
[0014] In the formula, To obtain the dimensionless perturbation coordinates in the Y direction, Let X be the dimensionless coordinate of the lower surface of the rotor airfoil. Let X be the dimensionless coordinate of the center of the disturbance region, and A be the magnitude of the dimensionless disturbance coordinate.
[0015] Optionally, the updated dimensionless coordinates of the upper and lower rotor airfoils are obtained based on the parametric expressions, specifically:
[0016] Determine an optimal one To achieve optimal control of rotor airfoil aerodynamic torque: select multiple [variables] within the first preset variation range. Multiple Substituting into the parameterized expression, multiple rotor airfoil aerodynamic shapes are obtained. The aerodynamic torque reduction for each rotor airfoil is calculated, and the value corresponding to the maximum aerodynamic torque reduction is taken. The optimal
[0017] Determine the relationship between the reduction in aerodynamic torque Δm and the change of parameter A: Select a value from the second preset range as parameter A, substitute parameter A into the parameterized expression to obtain a rotor airfoil aerodynamic shape, calculate the reduction in aerodynamic torque Δm of the rotor airfoil aerodynamic shape, assign the ratio of the reduction in aerodynamic torque Δm to parameter A to k, and obtain the relationship between the reduction in aerodynamic torque Δm and parameter A: Δm = kA;
[0018] Based on the requirement to reduce the aerodynamic torque of the rotor airfoil, the value of parameter A is determined according to the variation relationship Δm=kA. Substituting parameter A into the parameterized expression, the dimensionless perturbation coordinate in the Y direction is obtained.
[0019] For the lower surface of the rotor airfoil, the dimensionless perturbation coordinates in the Y direction under the same X-axis coordinate are... Compared with the original dimensionless Y-axis coordinate values The coordinates are superimposed to obtain the updated dimensionless coordinate values of the lower surface; for the upper surface of the rotor airfoil, the coordinate values are still the original dimensionless coordinate values in the X and Y directions.
[0020] Optionally, in step (1), the coordinate values of the upper and lower surfaces of the rotor airfoil are obtained from the cross-sectional shape coordinates of the rotor blade digital model through coordinate system transformation, or by searching through the airfoil database.
[0021] Furthermore, the method also includes:
[0022] Multiply the dimensionless coordinates of the updated upper and lower rotor airfoils by the chord length C to obtain the aerodynamic shape of the rotor airfoil after the torque reduction improvement design.
[0023] Optionally, the first preset variation range is 0.65 to 0.75. This ensures that the disturbance shape and the quarter chord point of the rotor airfoil maintain a sufficient distance, thereby generating sufficient aerodynamic torque control effect. At the same time, it ensures that the disturbance shape does not cause changes in aerodynamic parameters such as the leading edge radius, trailing edge angle, maximum thickness, and maximum camber of the rotor airfoil, thus maintaining good lift and drag characteristics while reducing torque.
[0024] Optionally, the second preset range is 0 to 0.01. In this way, the parameter A in the parameterized expression and the torque reduction have a linear relationship within this range, and the value within this range will not cause drastic changes in the rotor airfoil shape, thus avoiding any loss of lift and drag performance.
[0025] In a second aspect, an apparatus is provided for performing the method for reducing the aerodynamic torque of a helicopter rotor airfoil as described in any of the first aspects, comprising:
[0026] The calculation module uses parametric expressions to calculate the coordinates of the disturbed shape.
[0027] The superposition module is similar to superimposing the calculated disturbance shape coordinates onto the original rotor airfoil to obtain the improved airfoil aerodynamic shape, thereby reducing the aerodynamic torque.
[0028] The beneficial effects of this invention are at least as follows:
[0029] Based on extensive analysis and research on rotor airfoils, this invention proposes a parametric expression. This expression is used to improve and optimize the local shape of the rotor airfoil, thereby reducing aerodynamic torque. This method achieves quantitative control of the rotor airfoil's aerodynamic shape and aerodynamic torque through simple parameter adjustments, eliminating the need for time-consuming multi-round iterative calculations. The improvement and optimization do not require changes to key aerodynamic parameters such as maximum camber and maximum thickness of the rotor airfoil. While effectively reducing the rotor airfoil's aerodynamic torque, it maintains good lift and drag characteristics, thus minimizing the adverse effects of the improved design on helicopter flight performance. Attached Figure Description
[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0031] Figure 1 A schematic diagram of the aerodynamic shape parameters of a rotor airfoil with a thickness of 9.5%;
[0032] Figure 2 Schematic diagram of disturbance coordinates
[0033] Figure 3 A comparison of the dimensionless aerodynamic shapes of the original rotor airfoil with a thickness of 9.5% and the improved airfoil;
[0034] Figure 4 Comparison of the dimensionless aerodynamic shape of the original rotor airfoil with a thickness of 12% and the improved airfoil;
[0035] Figure 5 A comparison of the aerodynamic moment coefficients of the original rotor airfoil with a thickness of 9.5% and the improved airfoil (the moment coefficient in the figure is positive when it is tilted downwards);
[0036] Figure 6 A comparison chart of the aerodynamic drag coefficients of the original rotor airfoil with a thickness of 9.5% and the improved airfoil.
[0037] Figure 7 A comparison of the aerodynamic lift coefficients of the original rotor airfoil with a thickness of 9.5% and the improved airfoil.
[0038] Figure 8 A comparison of the aerodynamic moment coefficients of the original rotor airfoil with a thickness of 12% and the improved airfoil (the moment coefficient in the figure is positive when it is tilted downwards);
[0039] Figure 9 A comparison chart of the aerodynamic drag coefficients of the original rotor airfoil with a thickness of 12% and the improved airfoil.
[0040] Figure 10 This is a flowchart of the method of the present invention. Detailed Implementation
[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0042] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.
[0043] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited from each other.
[0044] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.
[0045] This invention provides an optimized design method for reducing the aerodynamic moment of helicopter rotor airfoils. It primarily achieves effective reduction of aerodynamic moment through local aerodynamic shape improvements to the airfoil, while maintaining good lift and drag characteristics. This invention has significant application value for reducing the control load on helicopter rotors, thereby improving helicopter weight efficiency and service life.
[0046] The specific implementation of the present invention will be described using two commonly used rotor airfoils with a maximum thickness of 9.5% and 12% as two application examples. The two rotor airfoils will be referred to as the 9.5% thickness rotor airfoil and the 12% thickness rotor airfoil, respectively.
[0047] First, regarding the 9.5% thickness rotor airfoil, see... Figure 10 The method for reducing the aerodynamic torque of the rotor airfoil in this invention shall be implemented according to the following steps:
[0048] (1) The coordinate values of the upper and lower surfaces of the 9.5% thickness rotor airfoil were obtained by measuring the cross-sectional shape coordinates of the rotor blade digital model and performing coordinate system transformation. The X direction of the coordinate system is the same as the chord direction, and the Y direction is perpendicular to the chord direction. The chord length C of the 9.5% thickness rotor airfoil was obtained by measuring the length of the chord.
[0049] (2) Using the chord length C as a reference, dimensionless processing is performed on the coordinates of the upper and lower surfaces of the rotor airfoil to obtain the dimensionless coordinates of the upper surface. and and the dimensionless coordinates of the lower surface and Figure 1A schematic diagram of the aerodynamic parameters of a 9.5% thickness rotor airfoil is provided. In the diagram, the chord line is the line connecting the leading and trailing edges; the X-direction is the chord direction of the rotor airfoil, and the Y-direction is the normal direction of the rotor airfoil. and as well as These are the dimensionless coordinates of the shape points on the upper and lower surfaces of the rotor airfoil, respectively.
[0050] (3) The perturbation coordinates for the optimization of the 9.5% thickness rotor airfoil shape are calculated using the parametric expressions in this invention. The parametric expressions are as follows:
[0051]
[0052] In the formula, To obtain the dimensionless perturbation coordinates in the Y direction, Let X be the dimensionless coordinate of the lower surface of the rotor airfoil. Let A be the dimensionless X-axis coordinate of the center of the disturbance region (which can be optimized to obtain the best torque control effect), and let A be the amplitude of the dimensionless disturbance coordinate (the torque coefficient can be quantitatively controlled by changing the value of A).
[0053] (4) Change within the range of 0.65 to 0.75 The value of will be different Substituting the parameterized expressions, multiple rotor airfoil aerodynamic shapes are obtained. The aerodynamic torque reduction for each rotor airfoil is calculated using CFD methods, and the value corresponding to the maximum aerodynamic torque reduction is taken. The optimal This step utilizes the open-source CFD software CFL3D to compare and analyze the reduction in aerodynamic torque. The turbulence model used in the calculation is the kω-SST model, and the rotor airfoil mesh employs a structured body-fitted mesh with good shape simulation accuracy. The thickness of the first mesh layer satisfies the requirement that Y+ is less than 1, and the outer boundary dimension of the mesh is 10 times the chord length. Based on the calculation results, the 9.5% thickness rotor airfoil exhibits optimal aerodynamic torque control. The value is 0.7.
[0054] (5) Take a value within the range of 0 to 0.01 as parameter A, substitute parameter A into the parameterized expression to obtain the aerodynamic shape of a rotor airfoil, and use the CFD software CFL3D to calculate the reduction in aerodynamic moment Δm of the rotor airfoil. From this, the relationship between the reduction in aerodynamic moment Δm of a 9.5% thickness rotor airfoil and the variation of parameter A can be obtained as Δm = 0.7A, where Δm is in the form of a dimensionless aerodynamic moment coefficient.
[0055] (6) In order to achieve a 5% reduction in aerodynamic torque at a lift coefficient of 0.6 for a 9.5% thickness rotor airfoil, If A and B are respectively set to 0.7 and 0.001, then the parameterized expression can be written in the following form:
[0056]
[0057] The disturbance coordinates calculated based on this parameterized expression are as follows: Figure 2 As shown.
[0058] (7) For the lower surface of the rotor airfoil, the dimensionless perturbation coordinates in the Y direction under the same X-axis coordinate are... Compared with the original dimensionless Y-axis coordinate values The coordinates are superimposed to obtain the updated dimensionless coordinate values of the lower surface; for the upper surface of the rotor airfoil, the coordinate values are still the original dimensionless coordinate values in the X and Y directions. Figure 3 A dimensionless aerodynamic shape comparison of the original and improved airfoils of a 9.5% thickness rotor airfoil is presented. It can be seen that, compared with the original airfoil, the improved airfoil only differs in the chordal direction on the lower surface of the airfoil. The aerodynamic shape of the local area was changed, but the main aerodynamic shape parameters such as the maximum thickness, maximum camber, maximum thickness chord position, and maximum camber chord position of the airfoil were not changed.
[0059] (8) Multiply the dimensionless coordinates of the updated upper and lower rotor airfoil surfaces by the chord length C to obtain the improved rotor airfoil aerodynamic shape.
[0060] Furthermore, for a 12% thickness rotor airfoil, the method for reducing the aerodynamic moment of the rotor airfoil in this invention is implemented. The specific steps of the implementation method are similar to those for a 9.5% thickness rotor airfoil, and will not be described in detail here. The parameterized expression... With A and 0.72 and 0.002 respectively, the disturbance shape coordinates are calculated, and then the calculated disturbance shape coordinates are superimposed onto the original rotor airfoil. Figure 4 A dimensionless aerodynamic shape comparison is given between the original airfoil and the improved airfoil with a 12% thickness rotor airfoil.
[0061] The following calculations of the aerodynamic moment, lift, and drag of the rotor airfoil before and after the shape update were performed using the CFD software CFL3D, thereby evaluating the technical effect of the improved airfoil in reducing aerodynamic moment in the two application cases of this invention.
[0062] Figure 5 The aerodynamic moment coefficients of the 9.5% thickness rotor airfoil before and after the improvement were obtained from CFD calculations under different lift coefficients. It can be clearly seen that the aerodynamic moment of the airfoil improved by this method is significantly reduced compared to the original airfoil. The aerodynamic moment is reduced by about 5% when the lift coefficient is 0.6. Figure 6A comparison of the drag coefficients of the 9.5% thickness rotor airfoil before and after the improvement, obtained from CFD calculations, clearly shows that the drag characteristics of the improved airfoil are basically the same as those of the original airfoil. Figure 7 A comparison of the lift coefficients of the 9.5% thickness rotor airfoil before and after the improvement, obtained by CFD calculation, clearly shows that the lift characteristics of the improved airfoil are basically the same as those of the original airfoil.
[0063] Figure 8 A comparison of the aerodynamic moment coefficients of the 12% thickness rotor airfoil before and after the improvement at different Mach numbers obtained by CFD calculation shows that the aerodynamic moment of the improved airfoil is significantly reduced compared to the original airfoil, with a reduction of about 13% at Mach number 0.7. Figure 9 A comparison of the drag coefficients of the 12% thickness rotor airfoil before and after the improvement, obtained from CFD calculations, clearly shows that the drag characteristics of the improved airfoil are basically the same as those of the original airfoil.
[0064] This demonstrates that the method can be applied to reduce aerodynamic torque under various operating conditions with different thicknesses, lift coefficients, and Mach numbers for rotor airfoils, while maintaining good lift and drag characteristics.
[0065] An embodiment of the present invention also provides an apparatus for performing the method for reducing the aerodynamic moment of a helicopter rotor airfoil as described in the embodiments of the present invention, comprising:
[0066] The calculation module uses parametric expressions to calculate the coordinates of the disturbed shape.
[0067] The superposition module is similar to superimposing the calculated disturbance shape coordinates onto the original rotor airfoil to obtain the improved airfoil aerodynamic shape, thereby reducing the aerodynamic torque.
[0068] The specific execution process of each module in this invention can be referred to the specific process of the relevant steps of the above method, and will not be repeated here.
[0069] It should be noted that the above process operations can be combined to varying degrees. For the sake of simplicity, the implementation methods of various combinations will not be elaborated further. Those skilled in the art can flexibly adjust or combine the order of the steps of the above method (or the position of the components of the product) according to the actual situation.
[0070] It should be noted that the functional components shown in the above embodiments can be implemented in hardware, software, or a combination of both. When implemented in hardware, they can be electronic circuits, application-specific integrated circuits (ASICs), plug-ins, function cards, etc. When implemented in software, they can be programs or code segments used to perform the required tasks. Programs or code segments can be stored in a machine or readable medium, or they can be transmitted over a transmission medium or communication link via data signals carried in a carrier wave.
[0071] The above description merely illustrates embodiments of the present invention and is quite specific and detailed; however, it should not be construed as limiting the scope of the patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Furthermore, any parts of the present invention not described in detail are conventional techniques.
Claims
1. A method for reducing the aerodynamic moment of a helicopter rotor airfoil, characterized in that, The disturbance shape coordinates are calculated using parametric expressions. The calculated disturbance shape coordinates are then superimposed onto the original rotor airfoil to obtain the improved airfoil aerodynamic shape, thereby reducing the aerodynamic torque.
2. The method according to claim 1, characterized in that, The method specifically includes: A parametric expression for improving and optimizing the local shape of a rotor airfoil is established. This parametric expression consists of a cosine function and a polynomial function, which can achieve a continuous and smooth transition of the rotor airfoil's aerodynamic shape. The updated dimensionless coordinates of the upper and lower surface rotor airfoils are obtained based on the parametric expressions.
3. The method according to claim 2, characterized in that, The specific parametric expression for optimizing the local shape of a rotor airfoil is as follows: (1) Obtain the chord length C of the original rotor airfoil and the coordinate values of the upper and lower surfaces of the airfoil; the chord length refers to the length of the chord line from the leading edge point to the trailing edge point of the airfoil. The airfoil coordinates take the leading edge point of the airfoil as the origin of the coordinates. The X direction of the coordinates is the same as the chord line direction, and the Y direction is perpendicular to the chord direction. (2) Using the rotor airfoil chord length C as a reference, dimensionless processing is performed on the coordinates of the upper and lower surfaces of the airfoil to obtain the dimensionless abscissa of the upper surface. and ordinate and the dimensionless abscissa of the lower surface and ordinate (3) Establish a parametric expression for improving and optimizing the local shape of the rotor airfoil. This parametric expression consists of a cosine function and a polynomial function, which can achieve a continuous and smooth transition of the rotor airfoil's aerodynamic shape. The parametric expression is as follows: In the formula, To obtain the dimensionless perturbation coordinates in the Y direction, Let X be the dimensionless coordinate of the lower surface of the rotor airfoil. Let X be the dimensionless coordinate of the center of the disturbance region, and A be the magnitude of the dimensionless disturbance coordinate.
4. The method according to claim 3, characterized in that, The updated dimensionless coordinates of the upper and lower rotor airfoils are obtained based on the parametric expressions, specifically: Determine an optimal one To achieve optimal control of rotor airfoil aerodynamic torque: select multiple [variables] within the first preset variation range. Multiple Substituting into the parameterized expression, multiple rotor airfoil aerodynamic shapes are obtained. The aerodynamic torque reduction for each rotor airfoil is calculated, and the value corresponding to the maximum aerodynamic torque reduction is taken. For optimal Determine the relationship between the reduction in aerodynamic torque Δm and the change of parameter A: Select a value from the second preset range as parameter A, substitute parameter A into the parameterized expression to obtain a rotor airfoil aerodynamic shape, calculate the reduction in aerodynamic torque Δm of the rotor airfoil aerodynamic shape, assign the ratio of the reduction in aerodynamic torque Δm to parameter A to k, and obtain the relationship between the reduction in aerodynamic torque Δm and parameter A: Δm = kA; Based on the requirement to reduce the aerodynamic torque of the rotor airfoil, the value of parameter A is determined according to the variation relationship Δm=kA. Substituting parameter A into the parameterized expression, the dimensionless perturbation coordinate in the Y direction is obtained. For the lower surface of the rotor airfoil, the dimensionless perturbation coordinates in the Y direction under the same X-axis coordinate are... Compared with the original dimensionless Y-axis coordinate values The coordinates are superimposed to obtain the updated dimensionless coordinate values of the lower surface; for the upper surface of the rotor airfoil, the coordinate values are still the original dimensionless coordinate values in the X and Y directions.
5. The method according to claim 1, characterized in that, In step (1), the coordinate values of the upper and lower surfaces of the rotor airfoil are obtained from the cross-sectional shape coordinates of the rotor blade digital model through coordinate system transformation, or by searching through the airfoil database.
6. The method according to claim 1, characterized in that, The method further includes: Multiply the dimensionless coordinates of the updated upper and lower rotor airfoils by the chord length C to obtain the aerodynamic shape of the rotor airfoil after the torque reduction improvement design.
7. The method according to claim 4, characterized in that, The first preset variation range is 0.65 to 0.
75.
8. The method according to claim 4, characterized in that, The second preset range is 0 to 0.
01.
9. An apparatus for performing the method for reducing the aerodynamic torque of a helicopter rotor airfoil according to any one of claims 1 to 8, characterized in that, include: The calculation module uses parametric expressions to calculate the coordinates of the disturbed shape. The superposition module is similar to superimposing the calculated disturbance shape coordinates onto the original rotor airfoil to obtain the improved airfoil aerodynamic shape, thereby reducing the aerodynamic torque.