湍流壁面脉动压力场测量技术:传声器阵列

在壁湍流中,壁面压力脉动虽然信号微弱,但包含了湍流中许多旋涡结构运动特征。本文详细介绍了一种传声器阵列测量技术,通过测量壁湍流壁面脉动压力场来快速检测壁湍流场中不同尺度的旋涡结构运动特征。为此,在自行设计的声耦合腔标定装置上对各传声器进行标定得到其幅频-相频响应特性传递函数。实验建立了传声器阵列测量系统,以后台阶湍流作为例,将16个传声器以阵列方式沿流向安装在台阶下游壁面上,对分离再附湍流的壁面脉动压力场进行了同步测量和信号重构。实验结果分析表明:传声器阵列测量技术可以很方便地捕捉到壁湍流中旋涡结构的非定常运动特征。这种传声器阵列脉动压力测量技术在风工程、空气动力学等非定常流动实验研究中有很好的应用价值。

Measurement of wall pressure fluctuations of turbulent flows: microphone array

Rich information of unsteady vortical structures immersed in wall turbulence is discernible in the weak signals of wall pressure fluctuations.Microphone array was thoroughly introduced for simultaneously measuring wall pressure fluctuations field.Toward this end,an in-house calibration tunnel was carefully made to obtain the amplitude-phase transfer function of each transducer.Turbulent separated and reattaching flow over a backward-facing step was employed as the benchmark-testing configuration,in which below the downstream wall 16 microphone transducers were placed in the streamwise direction.The reconstructed time-series data demonstrated that the microphone array rapidly captured the intermittent vortical structures,predicting the unsteady characteristics of the turbulent flow.