Development of lifetime imaging system for pressure-sensitive paint

We developed a lifetime imaging system to simultaneously measure pressure and temperature from the luminescent decay of PtTFPP. Analysis of PtTFPP-PSP by a streak camera showed that this PSP exhibited a transient behavior after pulsed excitation, similar to that suggested by Smoluchowski. Utilizing this characteristic, one could determine pressure and temperature by taking three images with different gated times. We built a lifetime imaging system composed of a pulsed laser and an intensified CCD (ICCD) camera. The three gated times of the ICCD were determined referring to the streak camera data. The performance of this system was evaluated over the wide range of pressure and temperature using a PSP-coated flat plate as a test article. As a result, we found that we could fit the ratios of the gated images with a smooth function of pressure and temperature. This allowed us to reconstruct pressure and pressure fields from the measured images. The accuracy of the lifetime imaging system was determined for various pressures and temperatures, and, as a verification test, pressure and temperature patterns induced by a sonic impingement flow were visualized by using this system.