低速航空声学风洞背景噪声测试技术研究

An investigation of background noise measurement technology in aeroacoustic wind tunnel

介绍了在国内第一个全新设计的0.55m×0.4m航空声学引导风洞开展风洞背景噪声测量的技术方案和方法,对电容式麦克风、脉动压力传感器、预极化和非预极化传声器、自由场和压力场传声器、传声器安装方式以及声学频谱算法进行了比较实验和分析。在初期实验过程中,根据测试结果优化了风洞降噪方案,达到了较为理想的风洞背景噪声指标。测试结果表明:采用电容式麦克风比采用脉动压力传感器得到的频谱和声压级精度高;在消声部段前后的同一侧洞壁上测量,可以得到消声部段传声损失;压力场和自由场传声器在修正后可以互换使用;为得到重复性较好的背景噪声频谱和有效声压级,采用频谱线性平均算法。实验结果对低速航空声学风洞背景噪声测试具有一定的指导意义。

This paper presented the background noise measurement technology scheme of 0. 55m × 0.4m aeroacoustic pilot wind tunnel newly designed in China. Some comparative tests and data analysis were made in it of condenser microphone, piezoresistive transducer, prepolarized microphone, externally polarized microphone, free-field microphone, pressure-field microphone, sensor installing methods and acoustic frequency spectrum algorithm. According to the obtained data, some measures were taken to optimize the noise reduction performance of the wind tunnel. It shows that condenser microphone is more accurate than piezoresistive transducer used for background noise measurement. After correction, pressure-field microphone and free-field microphone could be replaced by each other. Spectrum linear average algorithm should be used to calculate the muffler noise transmission loss for the sake of repetitive precision. The conclusion is helpful for background noise measurement of low speed aeroacoustic wind tunnel.