Infrared thermography in blowdown and intermittent hypersonic facilities

Abstract

Some results and conclusions from the application of infrared thermography in the measurement of heat transfer in two distinctly different short duration hypersonic facilities are presented. First results from a blowdown tunnel are discussed; they demonstrate the advantage of the infrared technique in providing twodimensional heat transfer maps as opposed to the zero-dimensional measurements enabled by discrete point gauges. The spatial resolution characteristics of the infrared scanning radiometer are sufficient to sense localized hot spots that may be quantified by concentrating the field of view onto the area of interest. In intermittent facilities, the technique is shown to provide qualitative information on the location of hot spots or, in a single-line scan mode, a heat transfer distribution along one direction. In the latter case, the presence of hot dust in the flowfield may pose problems in arriving at quantitative results.