Application of Planar Laser Rayleigh Scattering for Measurement of Gas Temperature Distributions in Effusion Jet Cooled Panels Exposed to High Temperatures

Abstract

This experimental study examines the use of planar laser Rayleigh scattering to measure instantaneous gas temperature distributions at different heights above the surface of an effusion cooled plate. An experimental test rig was used to model combustor conditions with a bulk crossflow temperature of 1500 K. Carbon dioxide was used as coolant at multiple blowing ratios ranging from 1.12 to 11.1. A “temperature-pegging” methodology was used to process Rayleigh light scattering images to create high resolution and accurate temperature images at heights of 2, 2.75, and 3.5 mm above the surface of a prototypical effusion plate. Measured temperature distributions were used to calculate root-mean-square (RMS) distributions, and were also converted to film effectiveness maps based on the upstream crossflow gas and effusion coolant temperatures. It is found that the film cooling region spreads upstream with increasing effusion jet blowing ratio parameter. The RMS deviation of gas temperatures over each measurement plane shows that the RMS fluctuations are low inside and outside the effusion film, but are high near the film edge. At a given height above the effusion panel, the RMS fluctuations decrease in the film region with increasing blowing ratio. Film effectiveness follows similar trends with high film effectiveness region expanding with increasing effusion jet blowing ratios.