Practical Experience With the Discrete Green’s Function Approach to Convective Heat Transfer

TLDR: In this paper, the authors measured the heat transfer from a short uniform heat flux strip beneath a turbulent boundary layer with and without freestream turbulence using a liquid crystal imaging technique.

Abstract: The heat transfer from a short uniform heat flux strip beneath a turbulent boundary layer with and without freestream turbulence was measured using a liquid crystal imaging technique. Data were taken for freestream turbulence intensities on the order of 12% and at momentum thickness Reynolds numbers on the order of 1,000 and 2,000 for the turbulent and steady freestreams respectively. Heat transfer enhancement due to the presence of freestream turbulence was measured in terms of the ratio of the average St on the heated strip for the turbulent freestream case to the steady freestream case. Compared to the baseline case of a uniformly heated surface upstream of the strip, the heat transfer enhancement decreased by 20%. The temperature distribution measured on and around the heated strip represented a kernel solution that was used by means of superposition to predict the heat transfer for any arbitrarily specified thermal boundary condition given the same flowfield. Predictions are compared against correlations and numerical predictions as well as data from the literature. The details and practical applications of this approach to handling heat transfer with non-uniform thermal boundary conditions are presented.