EVALUATION OF SEVERAL CALIBRATION TECHNIQUES FOR PRESSURE SENSITIVE PAINT IN TRANSONIC TESTING

A pressure sensitive paint (PSP) was applied to a large transonic wind tunnel testing of a rocket fairing model at M=0.9 and three paint calibration techniques were evaluated by comparing the paint data with intensive pressure tap measurements. A temperature sensitive paint (TSP) was also applied in a separate run to compensate for temperature dependency of the PSP. The test results showed an advantage of the in situ calibration with five pressure tap data because the taps covered a whole pressure and temperature range on the paint surface in this particular experiment. The simple a priori calibration was found to be unsuitable due to a temperature distribution at transonic regime. A newly proposed PSP/TSP combined calibration which used both the PSP and TSP measurements also showed good agreement with the pressure tap data without using any pressure tap data. This method would be useful in a blowdown tunnel application and a pressure measurement with an existing model with no pressure tap. However, further evaluation is necessary by taking both PSP and TSP images simultaneously. Finally, a linear affine transformation was applied to extract pressure data at an arbitrary point on the model and showed possibility of a future multi-camera application.