Development of Direct Wall Shear Stress Sensors
For realistic 3-D feedback flow control applications, wall measurements tend to be more practical than velocity field measurements. The measurement of mean and fluctuating wall shear-stress and pressure in a boundary layer finds applications both in industry and the scientific community. Time-resolved data can provide physical insight into complex flow phenomena, including turbulent viscous drag, transition to turbulence, and flow separation. The ability for the direct measurement of wall shear-stress as a vector field offers advantages over indirect measurements for pressure sensing for separation detection and flow state estimation for 3D flow control applications. Specifically, when the control objective is often skin-friction or pressure drag reduction, a direct measurement of these quantities may be preferable. This talk presents the design, fabrication and calibration developments of a direct MEMS-based capacitive shear stress sensing system to address both fundamental physics measurements and flow control applications.