Lifetime based pressure and temperature sensitive paint measurement on a civil aircraft wing under conditions near the onset of shock-induced separation

Abstract

Lifetime-based pressure- and temperature-sensitive paint (PSP and TSP) measurements were conducted in a large-scale industrial transonic wind tunnel to obtain high-quality pressure data for validation of computational fluid dynamics (CFD) simulations. A wind tunnel test was performed using the NASA common research model in the JAXA 2 m × 2 m transonic wind tunnel. The freestream Mach number was varied in the range of 0.70–0.89, and aerodynamic forces and moments were acquired in order to obtain the pitch break condition related to the onset of shock-induced separation. Polymer-based PSP was coated on a main wing of the model, and TSP was used in tandem with PSP to correct the temperature dependence of PSP. The two-gate lifetime-based method was applied to obtain the PSP and TSP emissions. An a-priori/in-situ hybrid calibration was conducted to convert ratio-of-ratios to pressure, and measured pressure distributions were mapped onto a three-dimensional (3D) model grid. The root-mean-square error for the pressure measurements was evaluated by pressure tap data and was approximated to be 0.8 kPa for all Mach numbers tested. The obtained pressure distributions exhibited a significantly high signal-to-noise ratio and were used for comparison with CFD results on a 3D grid. The high-spatial-resolution PSP measurements helped to accurately localize the differences from the CFD simulation results and showed that the prediction of the shock location along the main wing is still a relevant challenge.