Low-frequency and low-amplitude unsteady pressure measurement using polymer-type pressure sensitive paint

Abstract

Pressure sensitive paint (PSP) using poly(TMSP) as a polymer binder has high pressure sensitivity for low gauge pressure conditions observed in low-speed flows, which is important for research and development in mechanical engineering fields. Although the response time of poly(TMSP)-based PSP is of the order of milliseconds, which is slower than fast-response porous-type PSP, it may be useful for the measurement of nonstationary pressure distribution with low pressure amplitude as high as 100 Pa, if the frequency is not higher than the order of 100 Hz. In this study, we have investigated the nonstationary response of poly(TMSP)-based PSP, to evaluate the feasibility of the polymer-based PSP as a measurement tool for nonstationary low-speed flows. We have applied the poly(TMSP)-based PSP to measurement of nonstationary pressure distribution around a circular cylinder in low-speed flow, and compared the amplitude spectra of PSP and that of pressure probe, both of which are obtained by FFT analysis. As a result, it is clarified that the poly(TMSP)-based PSP can detect nonstationary pressure of 90 Hz with the amplitude of 70 Pa. For higher frequency the sensitivity of the poly(TMSP)-based PSP decreases, but the nonstationary pressure of 850 Hz with the amplitude of 310 Pa can be detected. Furthermore we have visualized the distribution of the integrated intensity of the PSP amplitude spectrum around the peak, to visualize the area with large pressure fluctuation on the cylinder.

Keywords

• pressure sensitive paint
• low-speed flows
• unsteady pressure distribution