Preliminary Design for GTE Research Grade CMC Combustor

Military-grade gas turbine engines are seeing increasing demands for operation at temperatures in excess of 1500°C, while future engines are projected to exceed 2000°C.  Because of this, the US Army is looking to implement ceramic matrix composite (CMC) components into their gas turbine engines (GTE). However, significant improvements must be made, specifically to the SiC-SiC material system, to achieve reliable performance in a combustor engine. These gas turbine engines require a system with improved state of the art thermal/environmental barrier coatings (EBCs) for limiting oxygen/water vapor transport, and high temperature phase stability, integration with metallic engine components mitigating thermal coefficient of expansion mismatch and optimized effusion combustion liner holes. All of these characteristics must be maintained at an affordable price, without exceeding material strength limits. This Phase I program proposed by Materials Research & Design seeks to incorporate design, analysis, fabrication, and testing into the development of reliable SiC-SiC material for a GTE combustor. At least two different manufacturing approaches will be assessed for this program, including pre-ceramic polymer infiltration and pyrolysis (PIP) and frequency assisted sintering technology (FAST). Finite element modeling will be done of a research prototype with measured and estimated properties for a SiC-SiC material system. These finite element models will be used to run thermo-structural analyses of the combustor based on approximate heating/mechanical loads. The designs will accommodate holes and channels for cooling of the liner and combustor can, while minimizing stresses seen from thermal gradients, mechanical loads and thermal expansion mismatches. Iterations will be performed until a design is ready to be fabricated with a thermal/environmental coating. Option tasks will include burner rig testing of the prototype, along with an advancement to the computational fluid dynamic (CFD) / conjugate hear transfer modeling of the combustion process, to ensure that the thermo-structural analysis is representative of an operational environment.