Hot-film sensors have been extensively used to determine the shear stress based on the heat transfer in the flow above the sensor. However, in unsteady flow a distortion in the shear stress signal is caused by the storage of heat in the sensor substrate. In this paper the heat transfer in the sensor is studied with a three-dimensional, transient conjugate heat transfer problem. The hot-film sensor is investigated numerically for the phase lag and the amplitude response in flow with an oscillating component. Experimental measurements on the frequency response behavior of a commercially available hot-film sensor in unsteady flow compare favorably with the numerical simulation results. With a data-analysis scheme based on an inverse method, the undistorted shear stress in unsteady flow is also recovered successfully from the hot-film measurements.
ASJC Scopus subject areas
- Mechanical Engineering