The measurement of luminescence from Pressure-Sensitive Paint (PSP) allows for the derivation of distributions of surface pressure. Traditional PSP systems can provide data with high spatial resolution; however, the bandwidth is limited to a few Hz by the response time of the paint. Fast responding paints have been developed using anodized aluminum and porous polymer formulations and these PSPs have demonstrated response times of up to 100 kHz. These fast PSPs have been used with traditional pulsed illumination sources and digital cameras to acquire instantaneous pressure distributions in unsteady flows. There is significant interest in combining fast responding PSP with high-frame-rate cameras to produce data that has both high spatial resolution and high temporal bandwidth. Unfortunately, older PSP illumination sources and fast framing cameras do not provide sufficient signal-to-noise ratio to acquire quantitative pressure data. Ultra-bright LEDs and fast framing cameras-that are now available-combined with porous polymer PSP, can be used to produce a system capable of both high spatial resolution and high bandwidth. Measurements of mean and unsteady pressure have been acquired on an experimental setup composed of a Mach-2 channel flow with transverse jet injection. Mean pressure distributions were acquired using a binary PSP system. The fast PSP system consisted of a porous polymer PSP illuminated with a diode array and imaged with a CMOS camera. Full frame images (for a 1k × 1k CMOS chip) were acquired at 7 kHz; reduced frame images were acquired at up to 25 kHz. The time averaged pressure data from the fast PSP system compared favorably to PSP data acquired using the binary FIB system. The unsteady pressure data clearly resolves structures not present in the mean pressure data. These structures include multiple lambda shocks upstream of a strong bow shock and high frequency perturbations in the location of these shocks. Significant deformations of the bow shock structure are detected as turbulent structures in the flow convect through the shocks and into the jet. Finally, a time series of data can be extracted at each image pixel and the spectral content and phase relationship of the flow can be investigated spatially. This type of spectral map can be created using arrays of fast pressure transducers; here, however, we present data representing an array of over 10,000 fast pressure transducers.
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