Hybrid Thermally Efficient Core (HyTEC) High Temperature CMC Vanes Final Report

The cooling of airfoils within a modern high-pressure turbine (HPT) presents a formidable challenge due to the high operating temperatures needed to support optimized cycles for reduced fuel burn. As engines become more fuel efficient, the turbine inlet temperatures continue to increase beyond the temperature capability of turbine airfoil materials. It is therefore necessary to have effective cooling designs in order to protect turbine components from the hot mainstream gases. The air used for cooling purposes is extracted from the high-pressure-compressor stages, which results in a performance penalty because the cooling air bypasses some of the work extraction of the first turbine stage. Therefore, for optimum performance, it is necessary to minimizing the amount of turbine cooling air.

The NASA HyTEC program focuses on improving U.S. based Original Engine Manufacturers (OEMs) in the advancement of critical technologies for the next generation of aircraft propulsion. Today, the vision of this future architecture includes engine hybridization and small core designs. To enable this vision, Pratt & Whitney has identified five (5) campaigns through the HyTEC program that will help bridge the TRL gap between today’s capability and the requirements of this architectural change. This contract is focused on implementation of Ceramic Matrix Composites (CMCs) in small core HPT.

The key benefit from high temperature CMC vanes will be the reduction in turbine cooling air derived from the high temperature capability of the CMC / EBC material system. The reduced turbine cooling air can then be traded for improved thrust specific fuel consumption (TSFC) for given flight points and integrated throughout the mission to calculate fuel burn reduction. The reduction in turbine cooling air from the high temp CMC vanes will be calculated by scaling the cooling requirements based on the temperature capability demonstrated by the CMC / EBC material system via testing in the HyTEC work scope. By decomposing the mission profile into temperature buckets, the required mission times at temperature will be established. Therefore, better performance of the material in the HyTEC testing will translate to less required cooling flow. Conversely, poorer performance of the material will translate to the need for more required cooling flow (and therefore, less overall benefit).

This final report will serve as a summary of the work completed under this contract and how each individual task performed against the Technical Performance Measures (TPM). This final report will include test results and conclusions from each of the individual Task Reports that were generated to status the program’s success and learning developed. At the conclusion of this report a status of all TPM’s and the present status of the associated Technology Readiness Levels (TRL) will be presented.