Low-Temperature Dependency Pressure-Sensitive Paints for Wind Tunnel Testing Based on Luminescent Polymer-Bound Porphyrins

Pressure Sensitive Paints (PSPs) are rapidly revolutionizing aerodynamic wind tunnel testing. PSPs incorporate pressure-sensitive luminescent molecules embedded in oxygen-permeable polymers to image the oxygen concentration, and by extension pressure, on the surfaces of vehicle and engine test models, informing the development of high-performance aerodynamic vehicles. However, current PSPs suffer from high temperature sensitivities, partly due to sensor molecule aggregation, introducing large errors in the measured pressure data. Here, we describe a luminescent Pt(II) porphyrin that is co -polymerized within a fluoroalkyl polymer to produce a PSP (PM1- co -FIB). PM1- co -FIB exhibits a remarkably low temperature sensitivity of 0.3% K –1, a 25% reduction when compared to the current commercial gold standard ISSI UniFIB. The efficacy of PM1- co -FIB PSP was demonstrated in a supersonic wind tunnel test on a flared cone geometry. It demonstrated excellent performance on the hottest (highest pressure error) section of the model, detecting a pressure of 41 kPa, a 7% discrepancy from the calculated value of 44.37 kPa. The PSP aerodynamic data is in excellent agreement with computational fluid dynamics simulations and is able to successfully visualize important aerodynamic phenomena including Görtler vortices.