Extended Surface Heat Transfer Coefficients via Endwall Temperature Measurements

Short pins are used for internal cooling of the trailing edge in a gas turbine blade. A novel method is described in this paper that helps in simplifying the experimental process used to obtain average heat transfer data on the pin surface, at the expense of additional postprocessing complexity. The method is based on a unique analytical solution of the longitudinal conduction equation with internal heat generation, allowing computation of average pin heat transfer rates via the pin base temperature measurements made with nonintrusive methods such as temperature-sensitive paint. The method is implemented on an experimental test rig consisting of an array of high-conductivity pins sandwiched between one adiabatic and one constant heat flux endwall. Verification of the novel method is done with comparisons to 1) the canonical solution of an infinite fin with and without internal heat generation, 2) conjugate computational results, and 3) experimental data validated against results from the literature. Comparison to the canonical analytical solutions shows negligible disagreement. As compared with computational simulations, results were in agreement within 2%. As compared with experiment, a difference of 7.3% or less was observed confirming the suitability of the method.