Dynamic Visualization of Boundary-Layer Transition in a Pitch-Sweep Test using a Carbon Nanotube TSP

Abstract

A combination of carbon nanotube and Temperature Sensitive Paint (cntTSP) has a potential to visualize dynamic movement of the boundary-layer transition on a model surface. 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 continuous model angle-sweep tests, which are desired in order to improve the data productivity of the wind tunnel tests. In this paper, the applicability of cntTSP to a continuous moving model (pitch-sweep test) is investigated in a low-speed wind tunnel. The laminar to turbulent boundary-layer transition appearing on a simplified airplane model wing is visualized and compared between the pitch-fix and pitch-sweep tests. With the model pitch angel varying transition patterns were successfully visualized by the cntTSP. Influences of the test parameters, e.g. sweep speed and direction, were examined and optimal parameters for the application of cntTSP in angle-sweep test are proposed in this paper.