An Experimental Study of Surface Temperature Distribution on Effusion-Cooled Plates

Abstract

A parametric study of temperature distribution on effusion-cooled plates under conditions typical for combustion chambers was performed using infrared thermography. In this investigation, the effects of different temperature ratios, velocity ratios of the two air streams, the injection hole spacing, inclination angle of the injection holes, and the thermal heat conductivity of the plates were studied. For a given amount of cooling air, the cooling efficiency was found to increase markedly with a reduction in hole spacing, i.e., when the number of holes was increased. Reducing the injection angle results in more attached jets, especially for small amounts of cooling air, and marginally lowers the wall temperature. A high thermal conductivity of the plate was found to decrease its surface temperature in front of the first row of holes but not the mean temperature in downstream positions. The most important operational parameters were the temperature ratio and the velocity ratio of the hot and cold air streams. An almost linear relation was found between the temperature ratio and the surface temperature when the jet velocity was large compared to the crossflow velocity. For plates with sparse hole spacing, a change in the velocity ratio had a small effect on the surface temperature, whereas the effect was large for dense hole spacings and the same amount of cooling air.