An experimental study of unsteady heat transfer from a flat plate to an oscillating air flow

In this paper, an experimental study of unsteady heat transfer from a uniformly heated flat plate to an oscillating air flow has been reported. To measure the instantaneous forced convection heat transfer coefficient from the plate, a schlieren interferometer with a Wollaston prism and an analyzer is applied. It was found that the amplitude and phase lag of the vibrating heat transfer coefficients depend on the dimensionless frequency S. At large S, the amplitude is proportional to 1/S and at S = 1, the amplitude has a maximum. The time average value of the vibrating heat transfer coefficients also depends on S, and is larger than the steady state value when S is close to unity.