基于MEMS传感器的高速风洞壁面剪切应力直接测量技术

Direct measurement technique of wall shear stress using MEMS sensors in a high-speed wind tunnel

提出了一种新的壁面剪切应力测量方法,使用锯齿状排布的MEMS传感器作为敏感元件,在高速风洞中对研制的剪切应力测量设备进行了原理验证实验。实验结果显示湍流中的局部壁面剪切应力大小是层流中的两倍以上,监测局部剪切应力可以作为一种有效的边界层转捩的实验判定方法。利用这一方法测得的转捩区与使用脉动压力测试技术测得结果一致,验证了通过MEMS元件监测局部剪切应力作为边界层转捩测量手段的可行性和可靠性。

This paper presents a direct measurement technique for wall shear stress. The capacitive MEMS sensor with pectinate floating element was developed. The techniques of static and dynamic calibration are introduced. The demonstrative experiment was carried out in a high-speed wind tunnel. The experiment results indicate that the local shear stress in turbulent flow is noticeably higher than in laminar flow. Monitoring local shear stress on a model can be also used for determining transition zone. In the present experiment, the transi- tion zone detected by the MEMS sensor is identical with what by the pressure transducer.