Surface pressure distribution imaging at frame rates over 1 kHz using porous pressure-sensitive paint

The aim of the present work is to demonstrate the feasibility of a porous pressure-sensitive paint (PSP) for time-resolved surface pressure measurements in unsteady flows. The porous PSP was composed of bathophenanthroline ruthenium(II) complex, Ru(Ph₂-phen), and a silica-gel thin-layer chromatography (TLC) aluminum plate. The dynamic response of the porous PSP was characterized by applying it to rapid pressure changes generated by a shock wave and a pulse-jet. The porous PSP was then applied to the transient starting process of flow in a two-dimensional Laval nozzle with a fast-framing complementary metal oxide semiconductor (CMOS) camera. It has been shown that the present imaging system can well capture a rapid flow evolution on the order of kilohertz such as shock wave motion in the nozzle during its starting process.