A dynamic resonant wall shear stress sensor for fluids

The measurement of fluctuating shear stress is one of the great unsolved instrumentation problems in fluid mechanics. Although shear stress measurement techniques have been investigated for more than 100 years by some of the most prominent fluid mechanics and instrumentation experts, the measurement of mean shear stress remains difficult, and rigorously calibrated sensors capable of measurements of fluctuating wall shear stress over a wide range of frequency and amplitude do not exist.; The goal of the present study is to explore an entirely new class of wall shear stress sensor. This sensor employs a novel dynamic-resonant sensing approach categorically different from that of the previously existing sensors. The dynamic-resonant sensor was run under open and closed-loop control in a channel flow test facility. Hot-Wire measurements taken at the exit of the channel flow facility were used to establish the flow regime in the channel. The static sensitivity plots for both the open and closed-loop operation of the sensor show an initial linear response at each drive level and that the highest sensitivity corresponded to the lowest drive value. These results agree qualitatively with the numerical results and provide a rigorous basis upon which further development of the dynamic resonant sensor can be pursued.