INVESTIGATION OF THE HEAT-ISLAND EFFECT FOR HEAT-FLUX MEASUREMENTS INSHORT-DURATION FACILITIES

This paper presents the results of an experimental investigation desig ned to determine the possible influence of a surface-temperature disco ntinuity on the heat-flux history inferred from the temperature histor y of a miniature thin-film heat-flux gage (painted on an insulator) em bedded in the surface of a metallic component. The resulting surface m aterial discontinuity has the potential of causing a heat-island effec t. Simultaneous measurements of the heat-flux history at selected loca tions along the midspan of a representative turbine airfoil (metal) we re performed using continuous strip-type contoured inserts (without te mperature discontinuity) and button-type inserts (with temperature dis continuity). Measurements are reported for two Reynolds number conditi ons. The experimental results suggest that for the experimental condit ions of interest to gas turbine research in short-duration facilities, the influence of a potential heat-island on the measured heat flux is insignificant.