Shear stress sensor using piezoelectric bimorphs bending

Abstract The measurement of shear stresses developed by a boundary layer is a fundamental problem of fluid dynamics. The knowledge of the mean stress and its fluctuations leads to a better description of the boundary layer and a better understanding of flow noise coupling. The values of the shear stresses to be measured in a laminar or a turbulent flow are only of a few pascal. The usual types of piezoelectric force sensors cannot perform this measurement with a satisfactory accuracy. The proposed sensor, composed of several piezoelectric bimorphs, performs a direct measurement of shear stresses. Its sensitivity is higher than 200 nC N −1 and this sensor allows measurement of shear stresses down to a few Pa.