调制气动声源声辐射特性实验研究

Experimental Research on Characteristics of Modulated Aerodynamics Acoustics Radiation

为提高调制气动声源在低频处的发声强度,将含声波的气流通过直管和双曲喇叭两种谐振管产生共振。通过实验研究在上述两种谐振管作用下,调制气流声源辐射强度与工作频率以及气室压力之间的关系。实验结果表明,当直管长度为调制声源1/4波长的奇数倍时,其辐射效果最好;双曲喇叭辐射强度与调制声源频率分段成比例。将谐振系统由直管改为双曲喇叭后其发声强度提高30 dB,而发声强度分段与气室压力成正比。

To raise the sound intensity of the modulated aerodynamic acoustic source in low frequency region, the resonances in two resonance pipes, a straight pipe and a bi-curved horn were tested by forcing the airflow of sound wave to pass through them. The relationship among sound radiation intensity, working frequency and chamber pressure in the two resonance pipes was studied experimentally. Results show that the best effect of the sound radiation will be obtained when the length of the straight pipe with constant cross-sections is the odd times of a quarter wave length of the sound source. While in the bi-curved horn with varying cross-sections the radiation intensity is proportional to the working frequency in different sections. The sound intensity can be raised 30 dB when the resonance pipe is changed from straight line type to the bi-curved horn type. And the intensity of sound in different sections is proportional to the chamber pressure.