A pressure sensitive paint (PSP) measurement is recently known as a pressure field measurement technique based on oxygen quenching phenomenon of luminescence of specific luminophores. A PSP measurement was applied to a pressure field measurement in a low-solidity circular cascade diffuser of a single-stage transonic centrifugal compressor at 17, 800 rpm with 5 in pressure ratio for HFC134a gas. The oxygen concentration was about 500 ppm based on the measured velocity of sound of the gas. Ru (bath-phen) was used as a PSP. The PSP was adsorbed on a silica-gel thin-layer chromatography sheet, and the sheet was fixed on the side-wall between the cascade vanes. The luminescent intensity drastically changed during a surge condition. And the pressure variations based on luminescent intensity agreed well with the pressure fluctuations measured using semiconductor pressure sensors with high-frequencyresponse at three points. It was shown that a PSP measurement worked well to investigate unsteady pressure fields in a transonic centrifugal compressor. However, there are still some problems to be overcome.
