Development of dynamic calibration system for high-frequency response evaluation of fast pressure-sensitive paint using cavity-induced flapping jet

A high-frequency dynamic calibration system for pressure-sensitive paint (PSP) was developed using cavity-induced jets. The dominant frequency for dynamic calibration was adjusted to the range of 9–16 kHz by scaling the cavity. The dominant flapping frequencies corresponding to different cavity lengths were identified. The distributions of pressure fluctuations across cavities were measured using fast PSP technology. An anodized-aluminum PSP (AA-PSP) with a free-based porphyrin luminophore (H \(_2\) TCPP) was utilized for pressure measurement. Instantaneous pressure fields were measured by combining a high-frequency dual-pulse laser and a high-speed camera. The denoising technique combining filtering and singular value decomposition (SVD) was applied, and the dominant pressure fluctuation components were extracted. The spatially averaged pressure amplitude and the uniformity of the pressure fluctuation fields were evaluated based on SVD. Potentially optimal calibration regions, exhibiting both high amplitude and uniformity, were identified on the Pareto front. Among them, the region exhibiting the highest pressure amplitude was selected as the optimal calibration region, which is located around the downstream slot. A point-measurement system for dynamic calibration of PSPs was constructed. The dynamic calibration of fast PSPs was performed. The gain attenuation and phase delay in the range of 9–16 kHz were evaluated. The calibration results exhibit good continuity with those obtained below 9 kHz using an acoustic resonance tube system. The cut-off frequency of AA-H \(_2\) TCPP and PC-Ru(dpp) \(_3\) at -3 dB are approximately 19.9 kHz and 18.9 kHz, respectively.