Abstract
Fast-response pressure sensitive paint (PSP) is used in this work to measure and analyze the acoustic pressure field in a rectangular cavity. The high spatial resolution and fast frequency response of PSP effectively captures the spatial and temporal detail of surface pressure resulting in the acoustic pressure field. In this work, a high-speed camera is used to generate a continuous time record of the acoustic pressure fluctuations with PSP. Since the level of the acoustic pressure is near the resolution limit of the sensor system, advanced analysis techniques are used to extract the spatial modes of the pressure field. Both dynamic mode decomposition (DMD) and proper orthogonal decomposition (POD) are compared with phase averaging for data analysis. While all three techniques effectively extract the pressure field and reduce the impact of sensor noise, DMD and POD are more robust techniques that can be applied to aperiodic or multi-frequency signals. Furthermore, DMD is better than POD at suppressing noise in particular regions of the spectrum and at effectively separating spectral energy when multiple acoustic excitation frequencies are present.
Highlights
Fast pressure-sensitive paint (PSP) is a class of optical sensors developed in recent years for quantitative measurement of unsteady surface pressure distribution on aerodynamic bodies
The luminophore used in the present study is platinum tetra porphyrin (PtTFPP), a solution of which was oversprayed onto the polymer/ceramic basecoat
For mode shape (1, 1, 0), the results obtained from the analytical solution (Equation (16)) and from phase-averaging are compared with dynamic mode decomposition (DMD)
Summary
Fast pressure-sensitive paint (PSP) is a class of optical sensors developed in recent years for quantitative measurement of unsteady surface pressure distribution on aerodynamic bodies. Sensors 2016, 16, 862 measurement of low-speed unsteady flows that exhibit very small surface pressure fluctuations Error sources such as temperature sensitivity and shot noise corrupt the fractional changes in PSP emissions [6]. Further reduction in signal-to-noise ratio (SNR) occurs when short-exposure high-speed imaging is used for time-resolved measurements To counter these error sources and to improve SNR in low-speed flows, phase-averaging methods have traditionally been used for unsteady measurements. With high-speed cameras, simultaneous recording of camera exposure time-stamps and a reference transducer signal can be used for post-process conditional averaging of the images [8,9] The disadvantage of this technique is the need for a periodic single-frequency signal for phase-locking the acquisition. High-speed imaging is used to capture the PSP response to the pressure fluctuations resulting from the acoustic field
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