| Surface temperature measuring techniques can be divided into the catogeries of point and thermal mapping techniques. By way of the point measuring techniques the surface temperature of only finite points on a model was measured every time, while with the thermal mapping techniques the surface temperature of whole a model was obtained. Also, thermal mapping techniques can be divided into the catogeries of coating and infrared thermal mapping techniques. The use of the former, in which certain temperature-sensitive paints were sprayed on a model, is limited. The latter, which had such these virtues as non-contact measurements, small flow field disturbances and larger measured areas, was widely applied in wind tunnel tests.The demonstration of heat-transfer measuring techniques and prospect of infrared thermal mapping techniques, main parts and performance indexes of a infrared camera, functional blocks and implementation of infrared processing software, experimental facility and measuring system of the wind tunnel has been made. The model emittance was experimentally determined and the three methods correcting directional emittance were compared. Those problems of the infinite-slab model thickness and constant wall heat rates hypothesis, the determination of adiabatic wall temperature were discussed in a 1-D heat conduction analysis. The tests were conducted in the Hypersonic Low Density Wind Tunnel at nominal test conditions of Mach 16, stagnation temperature 923K, stagnation pressure 1.40Mpa and 7.30Mpa. Heat-transfer data were obtained on a hemisphere model, a sharp cone and a big blunt cone respectively by means of infrared thermal mapping techniques, that of a 0.5mm thickness blunt cone by virtues of thermocouples. Furthermore, heat-transfer on all those models was calculated with the theoretical method. There is a good accordance between the above experimental data and the theoretical calculation. |
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