Development of a Highly Sensitive Temperature-Sensitive Paint for Measurements under Cryogenic Temperatures (100 - 160 K) Conditions

Abstract

A new temperature-sensitive paint (TSP) was developed to capture images with high signal-to-noise ratio in wind tunnel tests under cryogenic temperature (100 – 160 K) conditions. Typical applications of TSP are the detection of boundary-layer transition and the measurement of the temperature distribution on the model surface. Conventional TSPs based on Ru(terpy)_2Cl_2 as the temperature-sensitive luminophore have temperature sensitivities of less than 2 %K^-1 at 130 K. This sensitivity is not sufficient enough for TSP measurements in large industrial wind tunnels without considerable post-processing effort. The newly developed TSPs achieved a temperature sensitivity of about 4 %K^-1 at 130 K. Experiments were conducted in the cryogenic low-speed wind tunnel of the German-Dutch Wind Tunnel organization to evaluate the capability of these TSPs to detect boundary-layer transition. The new TSP formulations were proven to be capable to resolve small temperature differences and thereby detect boundary-layer transition with high accuracy.