Reduction of temperature effect in pressure-sensitive paint measurements by model materials and coatings

Pressure-Sensitive Paint (PSP) generally changes its luminescence intensity not only with pressure but also with temperature. The effect of temperature variations on a model surface decreases the measurement accuracy of PSP. Therefore, it is important to minimize temperature variations on the surface during wind tunnel testing. In this study, we have investigated the effect of model materials and coatings on the temperature variations on a model surface. Plate models made of three different materials: aluminium alloy, stainless steel, and wood with two thicknesses: 2 and 10 mm were prepared and then coated with PSP. Temperature variations on the model surfaces heated with hot air flow was measured by means of an infrared camera. The results revealed that the magnitude of the temperature variations on the model surface strongly depends on the model material and thickness, and applied coatings. The model with a higher heat capacity showed a smaller rate of temperature change on the model surface. Moreover, the models coated with PSP showed 2-3 times higher temperature change rates than those without the coating due to the low thermal conductivity of the applied layer. To resolve this problem, a high thermal conductive PSP has been developed by mixing high thermal conductive particles. This novel PSP successfully reduced the rate of the temperature change to almost the same level as a non-coated metal model surface.