An Optimization Methodology for Turbines Driven by Pulsed Detonation Combustors

Abstract

A step change in efficiency of gas turbine technology and, subsequently, an emissions reduction from this technology requires conceptual changes. Substituting conventional combustion chambers with pressure gain combustion in the form of pulsed detonation combustion (PDC) is one of the promising methods that can reduce gas turbine emissions significantly. Nevertheless, the component matching for the respective systems and specifically that of turbine expanders working with the exhaust flow of PDC tubes is still not solved. The unsteady nature of PDC exhaust flow makes threedimensionalcomputational fluid dynamics simulations too expensive to be applied in optimization loops in early design stages. To address this question, this paper introduces a new costeffective but reliable methodology for turbine analysis and optimization, based on the unsteady exhaust flow of pulsed detonation combustors. The methodology unitizes a robust unsteady onedimensional solver, a meanline performance analysis, and an adaptive surrogate optimization algorithm. A twostage axial turbine is optimized considering all unsteady flow features of a hydrogen–air PDC configuration with five PDC tubes. A threedimensional unsteady Reynoldsaveraged Navier stocks (URANS) simulation is performed for the optimized geometry and the baseline to evaluate the methodology. The results showed that the optimized turbine produces 16% lower entropy than the original one. Additionally, the turbine output power is increased by 14% by the optimized design. Based on the results, it is concluded that the approach is fast and reliable enough to be applied in optimizing any turbine working with unsteady flows, more specifically in PDC applications.