基于改进的传声器阵列数据分析技术的飞机机体噪声实验研究

 发展了一种平面传声器阵列数据处理新方法——洁净信号处理算法，通过对传声器阵列混淆和旁瓣信号的有效抑制，改进了对声源的分辨。基于改进的数据分析方法，研究了真实飞机结构和真实飞行条件下飞机起落架、襟翼等声源的频谱特性、指向特性。研究结果表明，新的信号处理算法可以更加清晰地分离出飞机表面的气动噪声源。起落架噪声的频谱是由宽频随机噪声与一些较为明显的单音噪声源组成，在不同辐射角度时，起落架噪声的声级在不同频率范围有一定的差异。襟翼侧缘噪声频谱是一个包含有个别明显单音噪声的宽频噪声谱，襟翼内侧缘噪声谱和外侧缘噪声谱有明显的差异，在低频范围,襟翼侧缘噪声的指向性比较明显，但在高频范围，襟翼侧缘噪声没有明显的指向性。

Experimental Study on Airframe Noise with Improved Data Reduction Method of Microphone Array Measurements

An improved data reduction method,called as the Clean Algorithm,for the measurement of aircraft flying noise with the large planar microphone array is developed.In the Clean Algorithm,the simulation of response of a point source at the position of maximum sound emission in source map is firstly carried out.Then,this response is subtracted from the source distribution to reduce the aliases and side lobes.This paper applies successfully the Clean Algorithm to flyover experiments with a planar microphone array which consists of 111 microphones,and focus are on the airframe noise sources,such as flap side-edge noise source,nose landing gear noise source,and main landing gear noise source.It is shown that the sound emission of the airframe structures can be identified distinctly.The improvement by Clean Algorithm is apparent.The spectra,directivity and sound pressure level of airframe noise are presented.It is found that the spectra of flap side-edge noise and landing gear noise are a broadband noise with some tones.Sound pressure level is different at different emission angle and in different frequency for the same noise source.