Towards the development of a deflagrative-based Pressure Gain Combustor: a combined experimental and numerical investigation

The growing need for high efficiency and low emission energy conversion systems has renewed interest in Pressure Gain Combustion (PGC) technologies, which offer the potential to exceed the thermodynamic limits of conventional constant pressure gas turbines. This thesis presents an integrated experimental and numerical investigation of a deflagrative-based PGC concept at an early stage of technological development. The research aims to advance the understanding, modeling, and system-level integration of this technology through four main objectives: experimental characterization of the prototype combustor, numerical modeling and validation, assessment of full-engine performance, and evaluation of turbine response under unsteady inlet conditions. A dedicated experimental campaign was conducted to characterize the combustor operation under representative conditions and to acquire high frequency data for numerical model validation. A one-dimensional model was then developed, and subsequently coupled with downstream turbines to analyze full system performance in two representative cases: a custom-designed turbine and a commercial unit. The simulations demonstrated potential cycle efficiency improvements of over 8\% compared to conventional Brayton cycles, with identified losses primarily related to heat transfer and incomplete combustion. An equivalent zero-dimensional cycle model was formulated to generalize the results and quantify performance trends across operating conditions. Finally, a novel Euler-based solver was developed to preliminarily assess turbine response to pulsating inflow, providing a physically consistent framework for future unsteady analyses. The combined experimental and numerical outcomes have contributed to advancing PGC technology toward its next stage of development, confirming the feasibility of deflagrative-based PGC integration within gas turbine systems and identifying opportunities for further efficiency improvements.