A grid-pattern PSP/TSP system for simultaneous pressure and temperature measurements

A novel combined pressure- and temperature-sensitive paint system has been developed for simultaneous pressure and temperature measurements using a monochrome camera. This grid-pattern PSP/TSP system consists of an array of PSP dots (PtTFPP in polymer-ceramic binder) on top of a TSP layer (Ru(dpp) in clearcoat). The physical separation of PSP and TSP eliminates problems involving chemical interactions and spectral interference which are commonly seen in dual-luminophore PSPs. Both PSP and TSP are excited by a 400 nm LED and the signals are captured simultaneously by a monochrome charged-couple device (CCD) camera. The key challenge is to precisely identify PSP and TSP regions from the grid pattern in each image. This has been realized by first creating a sharp environmental change in temperature or oxygen concentration, and then separating PSP region from TSP region based on the difference in intensity-ratio caused by paint properties. Full pressure and temperature fields are recovered by performing 2-D interpolation on PSP and TSP data, and the temperature field is then used to remove the temperature-induced errors in PSP results. This PSP/TSP system has been demonstrated in oblique jet impingement experiments.