Optical measurements of high-frequency pressure fluctuations using a pressure-sensitive paint and Cassegrain optics

Abstract

Optical measurements of high-frequency pressure fluctuations have been performed to examine the dynamic response of a fast-responding porous pressure-sensitive paint (PSP). The PSP was composed of meso-tetra(pentafluorophenyl) porphine and a commercial silica-gel thin-layer chromatography plate. Pressure fluctuations at frequencies on the order of kilohertz were produced on a flat plate by chopping an underexpanded air-jet and then measured by using a newly developed, optical pressure measurement system (OPMS) with a Cassegrain-type optical probe. Pressure traces obtained by the present OPMS and their amplitude spectra were compared with those obtained by a piezo-resistive pressure transducer. The present results demonstrate the feasibility of the present OPMS for measuring high-frequency pressure fluctuations with a high spatial resolution and reveal that the present porous PSP can follow pressure fluctuations at frequencies of several kilohertz at least.