Multi-trailing edge flap active control rotor aerodynamic noise rapid calculation method
By establishing aerodynamic data tables and rotorcraft models, and combining them with the FW-H equations, the problems of long calculation cycles and low accuracy of rotor noise were solved, enabling rapid and efficient assessment and accurate prediction of rotor noise.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-09
- Publication Date
- 2026-03-27
AI Technical Summary
Existing technologies for evaluating the aerodynamic noise of rotors with active control of multiple trailing edge flaps have long calculation cycles and cannot accurately account for the effects of blade elastic deformation, resulting in inaccurate noise prediction.
A rapid calculation method for rotor aerodynamic noise using active control with multiple trailing edge flaps is adopted. By establishing aerodynamic data tables, aerodynamic model of the rotorcraft, and FW-H equations, and combining the compact source method, the influence of blade elastic deformation is considered to quickly evaluate rotor noise.
It achieves fast, efficient, and accurate rotor noise calculation, and can provide precise load input under deformation conditions, thus improving the accuracy of noise prediction.
Smart Images
Figure CN121744487A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of helicopter rotor aerodynamic design technology, and relates to a method for rapid calculation of aerodynamic noise of a rotor with active control of multiple trailing edge flaps. Background Technology
[0002] The high noise level of helicopters is a major factor limiting their development and application. The aerodynamic noise generated by the rotor rotation is the main source of helicopter flight noise. Therefore, a lot of research has been conducted on the aerodynamic noise characteristics of rotors and noise reduction measures. Among them, arranging several flap sections at the trailing edge of the blade and applying active control is considered to be one of the promising technical directions for rotor noise reduction.
[0003] For aerodynamic noise assessment of rotors actively controlled by trailing edge flaps, high-precision CFD methods combined with the FW-H equations are mainly used for calculation. However, there are two shortcomings. First, it requires fine meshing of local areas such as the trailing edge flaps and the gap between the flaps and the blades. Moreover, the frequent mesh updates and flow field iterations during the high-frequency motion simulation of the trailing edge flaps result in extremely long calculation cycles. Second, rotor blades undergo elastic deformation during operation, especially when controlled by trailing edge flaps, where the elastic deformation becomes more significant. CFD-based methods cannot account for the influence of elastic deformation, thus failing to obtain the true blade surface load and providing accurate load input for noise calculation. This inevitably leads to inaccurate noise prediction. Summary of the Invention Purpose of the invention: To provide a rapid calculation method for aerodynamic noise of a rotor with active control of multiple trailing edge flaps, which can not only improve the calculation efficiency of rotor aerodynamic noise and meet the needs of rapid iterative design in engineering, but also make the noise calculation results of the trailing edge flap rotor, especially under large deformation conditions, more accurate.
[0004] The technical solution is as follows: A rapid calculation method for aerodynamic noise of a rotor with active control using multiple trailing edge flaps is proposed, and the steps are as follows: (1) Establish a table of aerodynamic data for a two-dimensional airfoil with trailing edge flaps; (2) Input the aerodynamic data table into the rotorcraft aerodynamics comprehensive analysis software; (3) Establish a conventional rotor aerodynamic / structural model in the rotorcraft aerodynamics comprehensive analysis software, and set parameters including overall parameters, aerodynamic parameters and structural parameters; (4) Add a trailing edge flap model to the conventional rotor aerodynamic / structural model and set parameters including flap configuration parameters and motion control parameters; (5) Perform the dynamics solution of the trailing edge flap rotor to obtain the blade surface load data; (6) Solve the rotor aerodynamic noise using the FW-H equation based on the compact source method.
[0005] Furthermore, step (1) specifically involves: for two-dimensional airfoils with different trailing edge flaps and flap deflection angles, performing aerodynamic flow field simulation using CFD, constructing an aerodynamic data table for subsequent three-dimensional calculation interpolation.
[0006] Furthermore, step (2) specifically involves inputting the aerodynamic data table into the rotorcraft aerodynamics comprehensive analysis software. The airfoil data table contains lift coefficient, drag coefficient, and moment coefficient data for the airfoil and flaps.
[0007] Furthermore, the overall parameters of step (3) are specifically: flight status and overall rotor parameters, including flight speed, flight attitude, rotor speed, rotor radius, number of blades, rotor control amount, and rotation direction.
[0008] Furthermore, the aerodynamic parameters in step (3) are specifically: aerodynamic shape parameters of the rotor blades, including airfoil arrangement, chord length distribution, and forward and backward sweep angles.
[0009] Furthermore, the structural parameters in step (3) are specifically: rotor structural parameters, including hub configuration parameters, blade mass distribution, flapping / swaying / torsional stiffness, cross-sectional moment of inertia, center of gravity distribution, and torsion angle distribution.
[0010] Furthermore, the trailing edge flap model in step (4) is specifically: a trailing edge flap aerodynamic / dynamic coupling model; The aerodynamic model is calculated using the free wake method to obtain the induced velocity distribution of the blade at different spanwise positions and different azimuth angles, thereby obtaining the effective angle of attack of the profile. Combined with the Mach number, the aerodynamic load of the blade profile is obtained by interpolation from the aerodynamic data table of the two-dimensional airfoil with trailing edge flaps. The dynamic model describes the blade with a complex structure as a one-dimensional beam and a two-dimensional cross-section. The flap deflection coordinate system is established with the flap rotation axis in the cross-section as the origin to describe the motion of the point on the trailing edge flap caused by the flap deflection. The kinetic energy and strain energy are further obtained by differentiation and variation. Based on Hamilton's principle, the dynamic differential equation of the trailing edge flap is constructed. The aerodynamic and dynamic models of the trailing edge flaps exchange information in a loosely coupled manner, and the calculated aerodynamic loads on the blade profile will take into account the influence of the blade elastic deformation caused by the high-frequency motion of the trailing edge flaps.
[0011] Furthermore, the flap configuration parameters in step (4) are specifically: the number of flaps, flap chord length, flap span, the chordal and thickness spacing of the flap axis relative to the 1 / 4 chord line of the blade, the center of gravity and mass of the flap, and the stiffness and damping of the flap axis hinge spring; the motion control parameters are specifically: the relevant control parameters of the flap motion deflection angle δ, including the static quantity θ of the flap deflection angle, the highest harmonic order M of the flap deflection motion, the amplitude of the higher-order deflection cosine DC, and the amplitude of the higher-order deflection sine DS, where DC and DS determine the motion phase; the formula for the flap motion deflection angle is as follows: ,in This represents the rotor's azimuth angle.
[0012] Furthermore, step (5) specifically involves: for flap motion δ under different amplitude, phase, and frequency control, solving the rotor aerodynamic / dynamic response, and quickly obtaining the blade profile aerodynamic load considering the influence of elastic deformation at different azimuth angles and spanwise positions, including the blade profile lift coefficient and drag coefficient.
[0013] Further, step (6) specifically involves: using the FW-H equation based on the compact source method, with noise calculation parameters including blade tip Mach number, harmonic order of spectral analysis, and blade surface load data as input, to solve the rotor load noise component; simultaneously, with blade chord length, torsion, and sweep angle parameters as input, to quickly obtain the rotor thickness noise component by fitting the shape of the blade with trailing edge flaps using the basis function; and superimposing the load noise component and the thickness noise component to obtain the rotor aerodynamic noise.
[0014] In summary, the beneficial effects of the present invention are as follows: The aerodynamic noise calculation method for actively controlled rotors with trailing edge flaps provided by this invention can quickly, efficiently, and accurately evaluate the noise value of any rotor with trailing edge flap combinations. For a 4m diameter multi-trail-edge flap actively controlled rotor blade, such as... Figure 1 As shown, modeling and evaluation of its rotor aerodynamic noise are performed. From Figure 2 It can be seen that the calculation results of this method are in good agreement with the experimental results, indicating high accuracy. Figure 3 It can be seen that this method can effectively evaluate the rotor noise reduction effect brought about by applying active control. Attached Figure Description
[0015] Figure 1 The rotor blade shape of the 4m diameter multi-trailing-edge flap active control system is used to implement the present invention; Figure 2 It compares the calculated values with the experimental values obtained by implementing the method of this invention; Figure 3 The method of this invention is used to calculate the impact of active control on rotor noise. Detailed Implementation
[0016] 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, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0017] A rapid calculation method for aerodynamic noise of a rotor with active control using multiple trailing edge flaps is proposed, and the steps are as follows: (1) Establish a table of aerodynamic data for a two-dimensional airfoil with trailing edge flaps; (2) Input the aerodynamic data table into the rotorcraft aerodynamics comprehensive analysis software; (3) Establish a conventional rotor aerodynamic / structural model in the rotorcraft aerodynamics comprehensive analysis software, and set parameters including overall parameters, aerodynamic parameters and structural parameters; (4) Add a trailing edge flap model to the conventional rotor aerodynamic / structural model and set parameters including flap configuration parameters and motion control parameters; (5) Perform the dynamics solution of the trailing edge flap rotor to obtain the blade surface load data; (6) Solve the rotor aerodynamic noise using the FW-H equation based on the compact source method.
[0018] The specific steps (1) are as follows: for two-dimensional airfoils with different trailing edge flaps and flap deflection angles, CFD is used to simulate the aerodynamic flow field and construct an aerodynamic data table for subsequent three-dimensional calculation interpolation.
[0019] The specific steps (2) are as follows: inputting the aerodynamic data table into the rotorcraft aerodynamic comprehensive analysis software. The airfoil data table contains data such as the lift coefficient, drag coefficient and moment coefficient of the airfoil and flaps.
[0020] The overall parameters in step (3) are: flight status and overall rotor parameters, including flight speed, flight attitude, rotor speed, rotor radius, number of blades, rotor control amount, and rotation direction.
[0021] The aerodynamic parameters in step (3) are specifically: aerodynamic shape parameters of the rotor blades, including airfoil arrangement, chord distribution, and sweep angle.
[0022] The structural parameters in step (3) are specifically: rotor structural parameters, including hub configuration parameters, blade mass distribution, flapping / swaying / torsional stiffness, cross-sectional moment of inertia, center of gravity distribution, and torsion angle distribution.
[0023] The trailing edge flap model in step (4) is specifically as follows: a coupled aerodynamic / dynamic model of the trailing edge flap. The aerodynamic model is calculated using the free wake method to obtain the induced velocity distribution of the blade at different spanwise positions and different azimuth angles, thereby obtaining the effective angle of attack of the profile. Combined with the Mach number, the aerodynamic load of the blade profile is obtained by interpolation from the aerodynamic data table of the two-dimensional airfoil with trailing edge flap. The dynamic model describes the blade with a complex structure as a one-dimensional beam and a two-dimensional profile. With the flap rotation axis in the profile as the origin, a trailing edge flap deflection coordinate system is established to describe the motion of the point on the trailing edge flap caused by the flap deflection. Kinetic energy, strain energy, etc. are further obtained through differentiation and variation. Based on Hamilton's principle, the dynamic differential equation of the trailing edge flap is constructed. The aerodynamic model and the dynamic model of the trailing edge flap exchange information in a loosely coupled manner.
[0024] The specific flap configuration parameters in step (4) are: number of flaps, flap chord length, flap span, chord and thickness spacing of the flap axis relative to the 1 / 4 chord line of the blade, flap center of gravity and mass, and flap axis hinge spring stiffness and damping. The specific motion control parameters are: relevant control parameters of the flap motion deflection angle δ, including the static quantity of the flap deflection angle θ, the highest harmonic order of the flap deflection motion M, the amplitude of the higher-order deflection cosine DC, and the amplitude of the higher-order deflection sine DS, where DC and DS determine the motion phase; the formula for the flap motion deflection angle is as follows: ,in This represents the rotor's azimuth angle.
[0025] The specific steps (5) are as follows: for flap motion δ under different amplitude, phase and frequency control, solve the rotor aerodynamic / dynamic response, and quickly obtain the blade profile aerodynamic load considering the influence of elastic deformation at different azimuth angles and spanwise positions, including the blade profile lift coefficient and drag coefficient.
[0026] The specific steps (6) are as follows: using the FW-H equation based on the compact source method, with noise calculation parameters including blade tip Mach number, harmonic order of spectral analysis, and blade surface load data as input, the rotor load noise component is solved; at the same time, with blade chord length, torsion, and sweep angle parameters as input, the rotor thickness noise component is quickly obtained by fitting the shape of the blade with trailing edge flaps through the basis function; the load noise component and the thickness noise component are superimposed to obtain the rotor aerodynamic noise.
[0027] Example A rapid calculation method for aerodynamic noise of a rotor with active control of multiple trailing edge flaps.
[0028] For a rotor with a diameter of 4m and 5 trailing edge winglets, Figure 1 The rotor blade profile for implementing the multi-trailing-edge flap active control of the present invention is given.
[0029] Figure 2 A comparison between calculated and experimental values for implementing the method of the present invention is provided to demonstrate the effectiveness of the method of the present invention.
[0030] Figure 3 The method of implementing this invention is presented to calculate the impact of active control on rotor noise. In the calculation, the trailing edge flap motion deflection angle is set to δ = -3° + 1.5sin(3Ωt). It can be seen that the rotor noise value is reduced after applying motion control.
[0031] Obviously, the embodiments described in the specific implementation details of this application are merely for the purpose of more clearly explaining the technical solutions in the specification, and are only a part of the embodiments of this application, and are not intended to limit this application. All other embodiments obtained by those skilled in the art based on the embodiments in the specific implementation details without creative effort should fall within the protection scope of this application.
Claims
1. A method for rapid calculation of aerodynamic noise of a rotor with active control of multiple trailing edge flaps, characterized in that, The steps are as follows: (1) Establish a table of aerodynamic data for a two-dimensional airfoil with trailing edge flaps; (2) Input the aerodynamic data table into the rotorcraft aerodynamics comprehensive analysis software; (3) Establish a conventional rotor aerodynamic / structural model in the rotorcraft aerodynamics comprehensive analysis software, and set parameters including overall parameters, aerodynamic parameters and structural parameters; (4) Add a trailing edge flap model to the conventional rotor aerodynamic / structural model and set parameters including flap configuration parameters and motion control parameters; (5) Perform the dynamics solution of the trailing edge flap rotor to obtain the blade surface load data; (6) Solve the rotor aerodynamic noise using the FW-H equation based on the compact source method.
2. The method according to claim 1, characterized in that: The specific steps (1) are as follows: for two-dimensional airfoils with different trailing edge flaps and flap deflection angles, CFD is used to simulate the aerodynamic flow field and construct an aerodynamic data table for subsequent three-dimensional calculation interpolation.
3. The method according to claim 2, characterized in that: The specific steps (2) are as follows: inputting the aerodynamic data table into the rotorcraft aerodynamic comprehensive analysis software. The airfoil data table contains the lift coefficient, drag coefficient and moment coefficient data of the airfoil and flaps.
4. The method according to claim 3, characterized in that: The overall parameters in step (3) are: flight status and overall rotor parameters, including flight speed, flight attitude, rotor speed, rotor radius, number of blades, rotor control amount, and rotation direction.
5. The method according to claim 4, characterized in that: The aerodynamic parameters in step (3) are specifically: aerodynamic shape parameters of the rotor blades, including airfoil arrangement, chord distribution, and sweep angle.
6. The method according to claim 5, characterized in that: The structural parameters in step (3) are specifically: rotor structural parameters, including hub configuration parameters, blade mass distribution, flapping / swaying / torsional stiffness, cross-sectional moment of inertia, center of gravity distribution, and torsion angle distribution.
7. The method according to claim 6, characterized in that: The trailing edge flap model in step (4) is specifically: the trailing edge flap aerodynamic / dynamic coupling model; The aerodynamic model is calculated using the free wake method to obtain the induced velocity distribution of the blade at different spanwise positions and different azimuth angles, thereby obtaining the effective angle of attack of the profile. Combined with the Mach number, the aerodynamic load of the blade profile is obtained by interpolation from the aerodynamic data table of the two-dimensional airfoil with trailing edge flaps. The dynamic model describes the blade with a complex structure as a one-dimensional beam and a two-dimensional cross-section. The flap deflection coordinate system is established with the flap rotation axis in the cross-section as the origin to describe the motion of the point on the trailing edge flap caused by the flap deflection. The kinetic energy and strain energy are further obtained by differentiation and variation. Based on Hamilton's principle, the dynamic differential equation of the trailing edge flap is constructed. The aerodynamic and dynamic models of the trailing edge flaps exchange information in a loosely coupled manner, and the calculated aerodynamic loads on the blade profile will take into account the influence of the blade elastic deformation caused by the high-frequency motion of the trailing edge flaps.
8. The method according to claim 7, characterized in that: The specific flap configuration parameters in step (4) are: number of flaps, flap chord length, flap span, chord and thickness spacing of the flap axis relative to the 1 / 4 chord line of the blade, flap center of gravity and mass, flap axis hinge spring stiffness and damping; the specific motion control parameters are: relevant control parameters of the flap motion deflection angle δ, including the static quantity of flap deflection angle θ, the highest harmonic order of flap deflection motion M, the amplitude of the higher order deflection cosine DC, and the amplitude of the higher order deflection sine DS, where DC and DS determine the motion phase; the formula for the flap motion deflection angle is as follows: ,in This represents the rotor's azimuth angle.
9. The method according to claim 8, characterized in that: The specific steps (5) are as follows: for flap motion δ under different amplitude, phase and frequency control, solve the rotor aerodynamic / dynamic response, and quickly obtain the blade profile aerodynamic load considering the influence of elastic deformation at different azimuth angles and spanwise positions, including the blade profile lift coefficient and drag coefficient.
10. The method according to claim 9, characterized in that: The specific steps (6) are as follows: using the FW-H equation based on the compact source method, with noise calculation parameters including blade tip Mach number, harmonic order of spectral analysis, and blade surface load data as input, the rotor load noise component is solved; at the same time, with blade chord length, torsion, and sweep angle parameters as input, the rotor thickness noise component is quickly obtained by fitting the shape of the blade with trailing edge flaps through the basis function; the load noise component and the thickness noise component are superimposed to obtain the rotor aerodynamic noise.