A Reduced Order Methodology for Optimizing Turbine Expanders Working With Rotating Detonation Combustors

Abstract Redesigning a gas turbine cycle with creative concepts is one of the most critical possibilities for achieving a significant increase in efficiency. Pressure Gain Combustion (PGC) can be used in place of conventional deflagration combustion since PGC contributes to a considerable gain in thermal efficiency while also emitting low NOx levels. One of the major challenges of PGC is the turbine integration to the outlet of the combustor due to the unsteady turbine inflow conditions. This unsteady exhaust flow causes turbomachinery components to operate under fluctuating off-design conditions which in turn, reduces their performance. In this work, the turbine integration to the Rotating Detonation Combustor (RDC) and an optimization methodology for the turbine are discussed. Due to the highly fluctuating unsteady flow of RDC, three-dimensional CFD simulation of turbine becomes very expensive, specifically if it is considered as the objective function evaluator in an optimization process. Thus, an alternative approach of using one-dimensional unsteady Euler model for the turbine is adopted. A two-stage axial turbine is optimized considering unsteady flow features of a hydrogen-air RDC to minimize the entropy generation. When compared to the baseline design, the optimized turbine shows a nearly 2.6% reduction in entropy generation.