水下MEMS壁面剪应力传感器标定方案仿真分析与实验验证

CFD analysis and experimental validation on the scheme of calibration for MEMS wall shear stress sensors array for underwater applications

壁面剪应力的精确测量对于研究水下物体边界层流动、寻求有效的减阻增效措施至关重要。MEMS壁面剪应力传感器的标定,首先是最基本的静态标定,决定了其测量的精度和数据的可信度。为辅助实现水下MEMS壁面剪应力传感器的精确标定,本文对采用槽道流法的精密标定装置流动条件进行数值仿真及激光多普勒测速仪测速实验,确定了标定试验段中流场从槽道入口处充分发展至稳定所需长度、压力分布情况及所能给定标定使用的壁面剪应力范围,进而设计标定方案;壁面剪应力的实验结果与数值计算和理论分析对比吻合较好,验证了标定方案的合理性,为下一步开展MEMS剪应力传感器阵列水下标定试验提供技术基础。

The measurement of wall shear stress on hydrodynamic surface is important for the design of advanced naval technology.Accurate calibration,first of all the essential static calibration,of the shear stress sensor is indispensable to any practical measurement.To aid the accurate calibration for MEMS wall shear stress sensors array for underwater applications,the flow field in the test section of a sophisticated calibrator which is a water flume based on the method of channel flow is numerically simulated in detail and verified by measurement with a Laser Doppler Anemometer（LDA）.The distance needed for the flow to fully develop from the inlet inside the flume is estimated,as well as the pressure distribution along the wall and the range of wall shear stress available for calibration operation.The scheme of calibration for MEMS wall shear stress sensors array for underwater applications is then designed and further validated with the good agreement among the results of shear stress obtained by theoretical analysis,CFD simulation and experiments respectively,which would be of use to the next calibration experiments for MEMS wall shear stress sensors array for underwater applications.