边界层效应对定程干涉法声速测量的影响

The Influence of Boundary Layer Effect on the Measurement of Speed of Sound Using Fixed Path Acoustic Resonator

定程干涉法是精度最高的气相声速测量方法,本文再现了定程干涉法共振频率的导出过程,在此基础上复现了边界层修正式的导出过程。最后以声速数据丰富的Ar为例,分析了边界层对这两种定程干涉法测量的影响规律。结果表明:边界层对定程干涉法声速测量有着显著的影响;边界层的影响随温度升高而增大、随压力升高而降低;适当增加共鸣腔体的几何尺寸有利于减小边界层效应的影响。

The speed of sound in gaseous phase can be measured with high precision by using fixed path acoustic resonator.In this paper,the resonance frequencies for speed of sound were reproduced. Then,the modifications about the influences of boundary layers were reproduced.At last,with the example of Ar,the influences of boundary layers on the measurement of speed of sound with cylindrical resonator and spherical resonator were analyzed and compared.The results indicate that： 1） the influence of boundary layer is remarkable,2） the influence of boundary layer increases with temperature rises while decreases with pressure increases,3） the influence of boundary layer decreases with the increasing of the size of resonator.