Gill Slot Trailing Edge Heat Transfer: Effects of Blowing Rate, Reynolds Number, and External Turbulence on Heat Transfer and Film Cooling Effectiveness

Abstract

Heat transfer and film cooling distributions have been acquired downstream from the exit of a nozzle guide vane gill slot (or cutback). Additionally, heat transfer and pressure drop data have been experimentally determined for a pin fin array within the gill slot geometry. Generally, average row pin fin heat transfer levels for the converging channel correlate quite well with archival literature. However, no generalized flow friction factor correlation was found to predict the pressure drop within the array. Experimental data for the region downstream from the gill slot have been acquired over a four to one range in vane exit condition Reynolds number, with low, grid, and aero-combustor turbulence conditions. At these conditions, both heat transfer and adiabatic film cooling distributions have been documented over a range of blowing ratios. Heat transfer distributions downstream from the gill slot ejection were found to be dependent on both ejection flow rate and external conditions. Generally, adiabatic film cooling levels are high but dissipate toward the trailing edge and provide some protection on the trailing edge. Heat transfer levels on the trailing edge are affected largely by the chord exit Reynolds number and the suction surface boundary layer condition. The present paper, together with a companion paper which documents gill slot aerodynamics, is intended to provide designers with the heat transfer and aerodynamic loss information needed to compare competing trailing edge designs.