Development of new two-component temperature-sensitive paint (TSP) for cryogenic testing

Two-component temperature-sensitive paint (TSP) for cryogenic wind tunnels has been newly developed to extend the highest working temperature up to 320 K, whereas a conventional single-component cryoTSP operates in the temperature range from 100 to 240 K. The two-component cryoTSP includes two luminophores: a ruthenium complex (Ru(trpy)2) and a europium complex, which are very temperature sensitive in the range of 100-240 K and 220-320 K, respectively. The ruthenium complex is excited by blue light while the europium complex requires UV light. One can thence operate the two luminophores independently by illuminating the paint at different wavelengths. Both luminophores emit red light, so that it is possible to use a single camera filter to observe both luminophores. Verification tests at different cryogenic wind tunnels proved that the two-component cryoTSP could detect a boundary layer transition line even up to room temperatures with only a single coating. This means that it is neither necessary to apply a different TSP coating to a model nor use an infrared camera when the wind tunnel is operated at room temperatures. As a result, the two-component cryoTSP enables one to save time and money in cryogenic testing.