Utilizing frequency response for medium-independent flow sensing

A flow sensor is being developed at IMTEK to perform flow measurements independently of a fluid's properties. In this paper, we discuss the effect of flow speed on the frequency response of the sensor. Experimental measurements are conducted for air in a mini wind tunnel. Normalized amplitude and phase shift between selected temperature signals exhibit a second order response. The results suggest that under a certain speed level, the frequency response is independent of the flow speed. Thus, it can be possible to determine the fluid's properties regardless its flow condition.