Application of pressure-sensitive paints to low-pressure range

The pressure-sensitive paint (PSP) technique has potential as a powerful diagnostic tool for measurements in the high Knudsen number regime because it is based on luminescence of molecules. Three types of PSP [two composed of organic dye and polymer (luminophore/binder), platinum octaethylporphyrin (PtOEP)/silicone polymer (GP197) and platinumtetrakis (pentafluorophenyl) porphyrin (PtTFPP)/poly[1-(trimethylsilyl)-propyne] [poly(TMSP)], and the other ruthenium II tris (4,7-diphenyl-l, 10-phenanthrolin chloride (Bath-Ru) adsorbed on anodized aluminum] are applied to the rarefied gas flow mainly lower than 150 Pa (about 1 torr) to examine fundamental properties, such as pressure/temperature sensitivity, time response of luminescence, and so on. The results show PtTFPP/poly(TMSP) to be the most suitable PSP among them for application in the low-pressure range because it has very high and linear sensitivity against oxygen pressure. However, temperature sensitivity of PtTFPP/poly(TMSP) is not negligible, and a correction of temperature is required for quantitative pressure measurement with high accuracy. Finally, pressure distribution of a surface on which a low-density supersonic freejet impinges is measured by the PSP.