Applications of Pixel-by-Pixel Calibration Method in Microscale Measurements With Pressure-Sensitive Paint

This paper presents the applications of pixel-by-pixel (P-b-P) calibration method for pressure-sensitive paint (PSP) in microscale measurements and the comparison with conventional single-point (S-P) calibration method. PSP has been applied to microscale measurements for its advantages of acquiring detailed pressure profiles and global maps. However, conventional S-P calibration method, which is commonly applied in macroscale measurements, has its restrictions in microscale measurements, and errors up to 77% are observed under the situation of nonuniform illumination. The deviation can result in misinterpretation of physics in the flow fields during data reduction. The P-b-P calibration method which utilizes every pixel on the photodetector as an individual pressure sensor has been examined for its effectiveness for correcting the luminescence deviation in microscale measurements due to nonuniform illumination, reflection from environments and channel geometry, and self-illumination between neighboring sensors. It successfully reveals correct pressure profiles inside polydimethylsiloxane microchannel in both longitudinal and lateral directions through the pressure map, thereby increasing the effective measurement domain across the microchannel width from 50% to 80%.