Status of Pressure Sensitive Paint Systems used in DNW

Abstract

In DNW a Pressure Sensitive Paint System (PSP) is in use at several wind tunnels which was originally developed by DLR and based on the intensity method. The intensity method has some drawbacks when operated in an industrial wind tunnel. Due to the necessity of image collection for wind off and wind on constellation the tunnel occupation time is nearly doubled. Although the lifetime-based PSP measurement has several advantages compared to the intensity-based method, it is still not a commonly-used PSP technique in wind tunnel testing. One problem is a non-uniform distribution of the measured lifetime over the coated surface. Theoretically PSP lifetime should be independent of the excitation light distribution, dye concentration and paint thickness; however, the measured lifetimes over the coated PSP surface are sometimes not uniform. As a first step, PtTFPP-based PSP for the lifetime-based method has been developed by DLR to improve this lifetime uniformity. In addition special attention was paid to the effect of basecoat material and polymer. The lifetime-based PSP method was applied to a transonic wind tunnel test. As a result, quantitative pressure distributions can be obtained by the lifetime-based method at M = 0.5 and 0.3. The PSP results show characteristic pressure distributions on a delta wing model which are compared to the results with the intensity method and numerical data.