A Data Reduction Procedure for Transient Heat Transfer Measurements in Long Internal Cooling Channels

Abstract

The effect of streamwise fluid temperature variation on the local heat transfer coefficient measurements in transient heat transfer tests in long channels is addressed. Previous methods are shown to result in considerable errors. A simplified model is proposed to characterize the local fluid temperature, which drives the heat transfer. With it, analytical solutions for the local wall temperature history are derived, which involve two unknowns, the local heat transfer coefficient and a lumped upstream heat transfer parameter. Using these solutions in the data reduction, these two parameters are determined from surface temperature measurements. Numerical experiments that simulate the physical experiment show the applicability and robustness of the proposed method. The method is finally demonstrated experimentally by investigating heat transfer in a smooth, square duct.