Hybrid Thermally Efficient Core (HyTEC) HyTEC Phase 1 – HTEBC Final Report

GEA is developing next generation clean-sheet, sustainable aviation propulsion systems with higher efficiency, use of sustainable fuels and the ability to provide dual and/or hybrid electric propulsion and power. These new engine systems are expected to demand engine cores capable of much higher energy density, hence significant increase in the thermal efficiency, thermal load, and thermal management of first and
second-stage turbine components relative to those of the state-of-art LEAP and 9X engines are needed.

GEA has demonstrated multiple advanced gas turbine engine hot section component designs using Silicon-Carbide Ceramic Matrix Composite (SiC-SiC CMC) material. The current state-of-art CMC systems include Gen 2 Environmental Barrier Coatings for service life durability. The CMC-Gen2 EBC system technology has been successfully applied to the design and development of several components of high pressure turbine hardware for advanced GEA CFM LEAP, GE 9X and military engine product hardware such as: combustor liners; turbine nozzles; turbine blades; turbine vanes & fairings. In the pursuit of higher material temperatures, GEA is maturing an alternative High Temperature Ceramic Matrix Composite (HTCMC) technology, based on an alternate Chemical Vapor Infiltration (CVI) process. HTCMC technology would be an enabler for achieving higher T3 and T4 operating conditions, increasing engine thermodynamic efficiency, which could effectively reduce the size and weight of the engine core.

The temperature capability of current generation Environmental Barrier Coating (EBC) systems in use on CMC components has a hard limit at the CMC-EBC interface driven by the melting point of the silicon bondcoat layer at 2550F. Therefore, GEA has been investigating novel material systems and concepts to overcome this hard limit. GEA recent advancements in this area have led to a novel composite bondcoat material system, which was successfully demonstrated under Navy VCAT program (ONR N0001410D0010). GEA-NASA HyTEC HTEBC program was designed to mature further the high temperature EBC system including GEA’s composite bondcoat system and NASA Glenn’s high temperature EBC system. The program was able to advance several high-temperature EBC architectures further with successful sequential demonstrations under commercial engine relevant conditions in NASA QARE rig and NASA CE-5 rig tests for TRL-4 and TRL-5 qualifications, respectively.

In addition, modeling efforts were initiated thru collaborations between GEA and NASA Glenn Research teams under this program to develop tools to predict the durability of the HTEBC architectures and to guide future material and component design development efforts. The primary focus of the modeling work was the development of a physics-based oxidation kinetics model for the complex composite bondcoat system. The collaborative development efforts successfully devised a 1D model to assess the oxidation life durability criteria set for the program.

Three different HTEBC architectures - one from NASA Glenn and two from GEA Research - were evaluated in the program through laboratory tests and burner-rig testing in simulated environment at NASA Glenn Research Center. Three leading candidates, one from each architecture, successfully completed TRL-4 and TRL-5 laboratory tests in cyclic steam at 2700F for 1000 hours, cyclic thermal gradient/transient for 1000 cycles with EBC surface temperature of 3000F and CMC/EBC interface temperature corresponding to 2700F for 1000 cycles, and 3000F for 250 hours exposure in the atmospheric natural gas/oxygen burner rig (QARE) tests at NASA. The three HTEBC architectures were subsequently applied to CVI CMC airfoil test articles. The coated CMC articles were subjected to over 76 hours of exposure to ~3000F combustion gas in the high-pressure combustor rig at NASA Glenn Research Center CE-5 test facility. All three candidate systems successfully completed their combustion rig test and met all program TPM exit criteria for TRL-5.