汽车风洞非均匀声场偏移导致纯音幅值变化

Variation of Pure Tone Sound Amplitude Caused by Non-Uniform Acoustic Field Deviation in Automobile Wind Tunnel

摘要:

从非均匀声场偏移角度研究汽车风洞流场外测量得到纯音信号声幅值伴随风速大幅变化的机理。以汽车表面可控声源为试验研究对象进行风洞试验，通过传声器获得不同风速下纯音声压级波动幅度，并使用传声器阵列观察到声场的非均匀分布。基于点声源干涉理论模拟重构了非均匀声场，参数化分析了各个反射壁面影响。根据几何声学理论推导剪切层折射产生的声场偏移，较为准确地预测了不同试验风速下纯音幅值变化的趋势。结果证明干涉产生非均匀声场经剪切层折射后偏移是风洞纯音幅值波动的根本原因，使用该声场重构方法能有效减小误差。

Abstract:

From the perspective of non-uniform sound field offset， the mechanism of pure-tone sound-amplitude large change with wind speed which measured outside flow field of automobile wind tunnel was studied. A wind tunnel test was conducted with a controllable sound source on the automobile surface as the research object. The amplitude fluctuation of pure tone sound pressure level at different wind speeds was obtained by microphone， and the non-uniform distribution of sound field was observed by microphone array. Based on the point source interference theory， the non-uniform sound field was simulated and reconstructed， and the influence of each reflecting wall was analyzed parametrically. The acoustic field offset caused by shear layer refraction was deduced according to the geometrical acoustic theory， and the trend of pure tone amplitude variation at different test wind speed was predicted. The results show that the deviation of the non-uniform sound field caused by the interference is the fundamental reason for the amplitude fluctuation of the pure sound in the wind tunnel， and the reconstruction method of acoustic field can effectively reduce the error.