Temperature Sensitive Paints for Ultra High Speed Acquisition and the Development towards the Determination of Flight Temperatures

Abstract

Temperature sensitive paints have been developed and applied during the time frame of more a decade now at the German Aerospace Center in Göttingen. This publication will give a review of the work conducted so far with this measurement technique and discuss the next steps of the development of this measurement technique towards flight experiments for high temperature hypersonic flows. The term high temperature hypersonic flows in the context of this publication refers to testing in ground facilities that generate hypersonic flows with total specific enthalpies, h0, in the range of 3 MJ/kg < 22 MJ/kg and the same for flight testing. In general, these flows are, due to the large demand of energy, generated in short duration ground test facilities (e.g. shock tubes, expansion tubes). The main demand on the technique of temperature sensitive paints, TSP, when applied in these facilities, is not only to measure temperature changes over time during the experiment, but the subsequent determination of surface heat fluxes from this time resolved temperatures measurements. Typically test times in these facilities are in the ms-range which means the technique has to be fast and acquisition ranges in the kHz and MHz ranges. The temperature changes remain low (<100°C) during the short test times, which simplifies the application and development of the colors somewhat. This is not the case, of the measurement techniques has to be extended to be applied in flight. The current status of the development towards the application in flight will be shown at the end of the publication.