Application of Temperature Sensitive Paint for time-resolved investigations of laminar-to-turbulent transition on a harmonically pitching airfoil under cryogenic conditions

Abstract

The combination of carbon nanotubes (CNT) and Temperature Sensitive Paint (cntTSP) has the potential to measure boundary-layer transition on harmonically pitching wind tunnel airfoil models in a time-resolved manner. The cntTSP sensor can visualize the surface boundary-layer conditions as temperature distribution based on different heat transfer coefficients in the laminar and turbulent flow. One wide area of interest for the use of cntTSP is the integration of the different cntTSP layers into complex wind tunnel model geometries, which is desired in order to improve the data quality of the wind tunnel tests. In this paper, the applicability of cntTSP to a forced pitch-oscillating airfoil model is investigated in a cryogenic low-speed wind tunnel. The laminar to turbulent boundary-layer transition appearing on the airfoil was successfully measured for steady and unsteady pitch cases.