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CN-121994449-A - Wind tunnel test method for evaluating pneumatic noise performance of rotary wing aircraft

CN121994449ACN 121994449 ACN121994449 ACN 121994449ACN-121994449-A

Abstract

The invention discloses a wind tunnel test method for evaluating pneumatic noise performance of a rotor craft, which belongs to the field of wind tunnel tests, comprehensively considers the influence of pneumatic noise characteristics of the rotor craft and acoustic wind tunnel environments, provides a standard wind tunnel test method for pneumatic noise of the rotor craft, can effectively measure the pneumatic noise radiation characteristics of the rotor craft, establishes a standard wind tunnel test data processing flow and method for pneumatic noise of a rotor craft model, provides an extrapolation method for pneumatic noise wind tunnel test results of the rotor craft model to real objects, can effectively correct the influence of background noise, wind tunnel jet shear layers, atmospheric sound absorption, doppler, model scale and the like on test evaluation, and effectively improves the accuracy of the pneumatic noise characteristic evaluation of the rotor craft. The test method has the advantages of standard flow, clear data processing theory and feasible data processing method, and can provide means and technical support for the pneumatic noise performance evaluation of the rotor craft.

Inventors

  • CHEN ZHENGWU
  • ZHANG WEIGUO
  • LU XIANGYU
  • ZHENG XIE

Assignees

  • 中国空气动力研究与发展中心低速空气动力研究所

Dates

Publication Date
20260508
Application Date
20260410

Claims (8)

  1. 1. A wind tunnel test method for evaluating pneumatic noise performance of a rotor craft is characterized by comprising the following steps: S1, sequentially installing a rotor craft test bed and a far-field noise measurement system in the center of an acoustic wind tunnel, and debugging; S2, measuring background noise when the rotor craft model is not taken at a given wind speed; s3, installing a body model with a rotor hub on a rotor wing test bed, and measuring aerodynamic noise of the body model under the condition of given wind speed and rotor hub rotating speed; S4, installing a rotor wing model, and measuring the pneumatic noise of the rotor wing aircraft model under the conditions of given wind speed and model state; S5, carrying out data processing and correction on the aerodynamic noise data of the rotary wing aircraft model; and S6, carrying out Doppler effect correction and model scale correction on the processed data, and carrying out characteristic evaluation on the aerodynamic noise of the rotary wing aircraft, wherein the Doppler effect correction and the model scale correction are used for extrapolating test results to a real object.
  2. 2. The wind tunnel test method for evaluating aerodynamic noise performance of a rotary wing aircraft according to claim 1, wherein the far-field noise measurement system comprises a plurality of circular arc microphone arms positioned outside wind tunnel jet flow, and a plurality of free field microphones are arranged on the circular arc microphone arms.
  3. 3. The wind tunnel test method for evaluating aerodynamic noise performance of a rotary wing aircraft according to claim 2, wherein the radius of the circular arc microphone arm is not smaller than 3 times of the characteristic dimension of the rotary wing aircraft.
  4. 4. Wind tunnel test method for evaluating aerodynamic noise performance of a rotary-wing aircraft according to claim 2, characterized in that the angle between adjacent free-field microphones on each circular-arc microphone arm and the centre of the arm is not more than 10 °, and that the arrangement range of all free-field microphones on the circular-arc microphone arm covers at least 0 ° to 70 °.
  5. 5. The wind tunnel test method for evaluating aerodynamic noise performance of a rotary wing aircraft according to claim 4, wherein the center of one circular arc-shaped microphone arm is located at the center of the wind tunnel, and the azimuth angles of the adjacent circular arc-shaped microphone arms relative to the center of the wind tunnel are not more than 60 °.
  6. 6. Wind tunnel test method for the performance evaluation of aerodynamic noise of a rotorcraft according to claim 1, characterized in that said rotorcraft model aerodynamic noise measurement comprises the following steps: s401, starting a rotor craft test bed, and adjusting a rotor craft model to a target attitude angle and a target rotor rotation speed; s402, starting a wind tunnel and adjusting to a target test wind speed; S403, controlling the attack angle of the rotor craft model to a test target value, balancing, adjusting the vertical force of the rotor craft model to the test target value, and adjusting to enable the pitching moment value and the rolling moment value of the rotor craft model to be close to zero; s404, collecting noise data according to set collection frequency and collection time; S405, repeating the processes of S401-S404 to finish all test working conditions; S406, stopping the wind tunnel, operating the rotor craft model in real time, ensuring that the rotor pulling force, pitching moment, rolling moment and system vibration are in a safe range, and gradually reducing the rotating speed of the rotor craft test bed to the stopping state.
  7. 7. A wind tunnel test method for evaluating aerodynamic noise performance of a rotorcraft according to claim 1, wherein said processing of aerodynamic noise data of a rotorcraft model comprises the steps of: s501, preprocessing data, including framing and filtering time domain discrete acoustic signals measured by a microphone; s502, performing spectrum analysis on the preprocessed data, and converting a time domain signal measured by a microphone into a frequency domain signal; s503, correcting background noise, performing wind tunnel background noise subtraction by adopting a spectrum subtraction method, and inhibiting the influence of other noise such as background noise and the like on rotor noise by adopting a phase averaging method, wherein the phase averaging method is as follows: , in the formula, For the maximum average frame number, determined by the signal-to-noise ratio requirement, For the 1 st frame and the 1 st The time corresponding to the phase shift of the frame, For the extracted rotor aerodynamic noise time domain discrete signal, Is the first The time domain discrete signal after the frame background noise subtraction, S504, correcting the influence of the microphone according to correction factors of a protective cover, a hood and a nose cone of the microphone; s505, correcting the influence of the airflow shear layer, including propagation path correction and amplitude correction; s506, correcting the atmospheric sound absorption effect.
  8. 8. A wind tunnel test method for evaluating aerodynamic noise performance of a rotorcraft according to claim 1, wherein said doppler effect correction is used to correct the effect of the physical movement of the rotorcraft on the propagation of sound, comprising: The propagation path is modified so that, , The frequency is corrected and, in this way, , The model scale correction is used for extrapolation of aerodynamic noise wind tunnel test results of the rotor aircraft scaling model to a full-size model under the condition of meeting aerodynamic acoustic similarity criteria, and comprises model scaling correction and distance influence correction, and the correction method comprises the following steps: , Wherein: the distance from the model to the microphone in the wind tunnel test, The angle of incidence of sound waves from the sound source to the microphone during wind tunnel test, The acoustic frequency of the rotor craft model radiation during wind tunnel test, For the Mach number of the wind tunnel test, For the distance between the rotorcraft model and the survey point, In order that the corrected sound frequency corresponds to the sound frequency of the physical radiation, Is the characteristic scale of the real object of the rotorcraft, Is a characteristic dimension of a rotorcraft model, For the distance between the object of the rotorcraft and the measuring point, The sound pressure level of the rotor craft model after wind tunnel test data processing, Is the sound pressure level of the real object of the rotorcraft.

Description

Wind tunnel test method for evaluating pneumatic noise performance of rotary wing aircraft Technical Field The invention relates to the field of wind tunnel tests, in particular to a wind tunnel test method for evaluating aerodynamic noise performance of a rotary wing aircraft. Background The helicopter, gyroplane, eVTOL and other gyroplane generally provide lift force, propulsion force and operating force by the gyroplane, have unique performances of vertical take-off and landing, hovering, low-altitude low-speed flight and the like, the moving range and the speed range of the gyroplane can effectively fill the blank of the modern space-ground transportation equipment in speed and space, play an important role in the national economy construction field, and particularly various gyroplanes, multi-gyroplanes, eVTOL and other low-altitude gyroplanes are in vigorous development along with the rapid rise of low-altitude economy in the world in recent years, and urgent demands are put forward for high-performance gyroplanes. The rotor generates lift force and propelling force through high-speed rotation of the rotor, and when huge power is generated, the interaction of the high-speed rotating blades of the rotor and surrounding air flow can generate strong pneumatic noise, and the high-speed rotating blades of the rotor have important influence on the acoustic performance of the rotor craft such as a helicopter, eVTOL and the like, so that the accurate evaluation of the pneumatic noise characteristics of the rotor is very important for developing the rotor craft with high quality. The rotor aerodynamic noise has complex components, including thickness noise, load noise, pitch vortex interference noise, high-speed impulse noise, broadband noise and the like, and the different types of noise generation mechanisms are different, so that the propagation mechanism in a space flow field is extremely complex, a reliable rotor aerodynamic noise test method is required to be developed based on the complex radiation characteristics of the rotor aerodynamic noise, the rotor noise radiation characteristics are evaluated, and the rotor aircraft noise reduction optimization design and the low-noise flight trajectory optimization are guided. At present, a plurality of aviation acoustic wind tunnels are established in a domestic manner, a good test platform is provided for the pneumatic noise research of the rotor craft, in order to accurately and reliably measure the pneumatic noise performance of the rotor craft, a wind tunnel test method for evaluating the pneumatic noise performance of the rotor craft is established by relying on the acoustic wind tunnels, the processing flow of the pneumatic noise wind tunnel test data of the rotor craft is standardized and unified, the extrapolation method of the pneumatic noise wind tunnel test data of the rotor craft to a real object is developed, the effective pneumatic noise wind tunnel test evaluation capability of the rotor craft is formed, and the pneumatic noise evaluation and noise reduction research verification of the advanced rotor craft are supported. Disclosure of Invention The invention aims to accurately measure noise of different directions of a rotor wing in an acoustic wind tunnel, process data of system specifications, correct the influence of factors such as wind tunnel background noise, a microphone self structure, a wind tunnel jet flow shearing layer, an atmospheric sound absorption effect and the like on noise measurement accuracy, accurately acquire noise radiation characteristics of the rotor wing under different working conditions, extrapolate the pneumatic noise wind tunnel test result of the rotor wing aircraft to a real object, and provide technical support for the pneumatic noise evaluation and noise reduction method verification of the rotor wing aircraft. In order to achieve the above purpose, the present invention adopts the following technical scheme: The invention discloses a wind tunnel test method for evaluating aerodynamic noise performance of a rotor craft, which comprises a rotor craft model aerodynamic noise wind tunnel test method and a test data processing method. The method for testing the aerodynamic noise wind tunnel of the rotor craft model comprises the following steps. S1, installing and debugging test equipment, and sequentially installing test equipment such as a test bed of a rotor aircraft, a far-field noise measurement system and the like in the center of an acoustic wind tunnel. The far-field noise measuring system consists of a plurality of 1/4 circular arc microphone support arms, a free field microphone, synchronous data acquisition equipment and the like. The radius of the 1/4 circular arc microphone support arm is not smaller than the characteristic scale of the 3-time rotor craft and is positioned outside the wind tunnel jet, a plurality of free field microphones are arranged on the 1/4 circular arc microphone support arm, the