Demonstration of high porosity cooling systems using novel Thermochromic Liquid Crystal approach

Authors

Augustin Wambersie  - University of Oxford Thermofluids Institute, United Kingdom
Peter Ireland - University of Oxford Thermofluids Institute, United Kingdom

Abstract

High porosity cooling systems have recently shown promise as a potential option for increasing turbine blade film effectiveness. In order to demonstrate the viability of such an approach, a set of turbine blades based on the same high porosity, double wall design was manufactured from engine grade materials. These were tested for metal effectiveness at steady state within a low temperature high speed cascade at various mass flows.   Metal effectiveness values were obtained using a novel post processing technique, based on the response of multiple narrow band liquid crystals. This approach allows for a very high spatial resolution of blade surface temperatures within engine like flow conditions. The combination of multiple LC bands also allows for a high enough degree of temperature specificity for spanwise average and area averages to accurately quantify the overall blade cooling performance. Results demonstrated the high cooling potential of such designs as well as their viability within a double walled system. The comparisons between the measured metal effectiveness values to existing literature on existing cooling designs suggests that the potential increase in cooling effectiveness exceeds 5-7% at existing mass flows, or alternatively allow for a match in cooling performance with a 15-20% reduction in coolant mass flow.