High-frequency pressure fluctuations in vertical jet impingements: fast pressure-sensitive paint analysis

In this paper, a fast-PSP measurement system using the intensity method is constructed to capture the fluctuating pressure field generated by the vertical supersonic (Ma = 1.2) jet impingement on a plate at different impingement distances. The paint formulation is optimized by adding a specific proportion of epoxy resin binder to PC-PSP primer, resulting in no significant peeling even after approximately 100 jet impingements. The light intensity decreased by 12.75% over 35 jet impingements (Ma = 0.7–1.2) without adjusting the light source power. The paint is calibrated and found to have a response time of 83 μs, a pressure sensitivity of 0.5833%/kPa, and a temperature sensitivity of 1.9%/K at 20 °C. The experiment is conducted in an anechoic chamber to investigate the effect of vertical jet impingement on a flat plate with impingement distances (L/d) ranging from 2 to 5. The PSP system captured dynamic pressure signals with a frequency of up to 9212 Hz (L/d = 2). Analysis of the surface pressure distribution in a period showed that an alternating axisymmetrical ring structure is formed in the periphery due to the interaction of expansion and compression waves at the impingement center. The evolving radius of the ring structure over time indicated that its outward expansion speed initially increases and then decreases. The proposed PSP measurement system provides technical assistance for investigating noise mechanisms in close-range vertical jet impingement.

Graphical abstract