鼻锥声学特性试验研究

该文内容涉及在气流当中进行声学测量存在的传感器自噪声问题。在速度为10m/s以下的气流中测量噪声,通常用泡沫球形风罩可有效降低气流流过传声器时产生的噪声(称为传感器自噪声)。在速度为10m/s以上时,为降低自噪声,传声器必须装上特殊形式的鼻锥。但风速达到某个数值以后,传声器自噪声仍会太大以至于无法进行声学测量。所以,在高速气流中进行声学测量时,传感器自噪声成为测量的制约因素。根据自噪声主要取决于鼻锥的边界层与透声孔干扰的论断,笔者用风洞实验的方法研究了三种形式鼻锥的声学特性,试图寻找降低自噪声水平和提高实验风速的方法。研究表明,在透声孔上覆盖纱网可以降低传感器自噪声。在本文的实验条件下,加纱网可以降低自噪声约5dB或在保持自噪声水平相同的条件下提高实验风速约10m/s。

An investigation of flow-induced noise of three different nose cones

This paper deals with flow-induced noise of microphone working in high speed flow.A spherical plastic foam cover was usually used to reduce sensor self-noise lever when flow speed is under 10m/s.Some special nose cones must be employed when flow velocity is higher than 10m/s for the same reason.The flow-induced noise lever,which limits the experiment flow speed,becomes higher and higher with increasing of flow velocity.An experiment was conducted to investigate the flow-induced noise of three different nose cones.The results showed that nose cone screen can reduce Sound Pressure Lever(SPL) of flow-induced noise by 5dB or permits to increase the speed of test flow by 10m/s if the background noise levels are same.