Accuracy of Conventional Adiabatic Effectiveness and Heat Transfer Augmentation Factors in Predicting Heat Flux Into a Turbine Blade Leading Edge

Abstract

This paper focuses on the legitimacy of using conventional predictions, based on adiabatic wall temperature (Taw) and heat transfer coefficient (HTC) augmentation, of heat flux into a film cooled leading edge. To answer this question, the heat flux predicted using Taw was compared to the heat flux into a conducting leading edge. The study used numerical simulations with the k-ε turbulence model of FLUENT. The model simulated was a three-row leading edge with one row of holes on the stagnation line and two additional rows located at ±25°, which has been experimentally studied extensively. The adiabatic wall temperature was obtained from an adiabatic simulation. External heat transfer coefficients were determined from a constant heat flux simulation using a density ratio of DR = 1.0, as is commonly done experimentally. A conjugate heat transfer simulation was also run to give the surface temperature and heat flux into the conducting leading edge. Overall, the heat transfer was well predicted with the use of Taw and HTC augmentation. However, between the holes, conventional predictions of heat transfer were poor, with disparity up to 30% when compared with the conducting wall heat flux obtained from the conjugate heat transfer simulation. Thermal boundary layer profiles were used to understand the disparity between the heat fluxes obtained from the conventional prediction and the conducting wall simulation.