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为了研究脉动喷气发动机噪声特性,搭建了Helmholtz型脉动喷气发动机噪声试验测试系统。对不同管长的脉动喷气发动机管外,不同距离、不同角度处发动机噪声进行了测量。试验结果表明:脉动喷气发动机噪声呈现周期性、低频性的特点;脉动喷气发动机噪声基频由其工作频率决定,噪声的基频成分对总噪声的贡献值最大;随着传播距离的增加,脉动喷气发动机噪声声压级逐渐减小,其衰减幅度略大于球面波衰减规律,不同角度处的噪声衰减规律几乎一致;不同传播距离处的噪声呈现出相同的轴向指向性;随着脉动喷气发动机尾喷管长度的增加,其噪声声压级及基频均随之降低,但尾喷管长度的增加对其噪声指向性没有影响。
In order to study the noise characteristics of the pulsating jet engine, a Helmholtz pulsating jet engine noise test system was set up. The engine noise at different distances and angles was measured outside the pulsating jet engine tube with different pipe lengths. The experimental results show that the noise of pulsating jet engine exhibits the characteristics of periodicity and low frequency. The fundamental frequency of pulsating jet engine is determined by its operating frequency, and the contribution of the fundamental component of noise to the total noise is the largest. With the propagation distance increasing, the pulsation The sound pressure level of jet engine decreases gradually, and its attenuation amplitude is slightly larger than that of spherical wave. The attenuation law of noise at different angles is almost the same. The noise at different propagation distances shows the same axial directivity. With the fluctuation of jet engine As the length of the nozzle increases, the noise level and the fundamental frequency decrease. However, the increase of the length of the nozzle has no effect on the noise directivity.