Experimental methodology for the characterization of a hydrogen-fuelled Pressure Gain Combustor

Gas turbines have been a key technology in many industrial sectors for over 50 years and they will continue to play a crucial role in the energetic scenario. Nevertheless, these systems are approaching their efficiency limits and performance improvements are becoming increasingly difficult to achieve. In this context, Pressure Gain Combustion (PGC) has emerged as a promising technology: replacing the isobaric combustion with a quasi-isochoric process creates a rise in total pressure across the combustion chamber, enhancing their potential performances. However, it is a complex process influenced by combustion chemistry, heat transfer, and fluid dynamics, and its unsteadiness increases the complexity of measurement campaigns. Thus, several challenges still need to be addressed for its development. This paper shows the experimental methodology followed to characterize an innovative deflagrative-based PGC fuelled with 100% hydrogen. Dynamic pressure sensors were installed inside, upstream, and downstream of the combustion chamber and acquired at a high frequency (1 MHz) to describe in detail the process. Downstream the combustor, an orifice simulated the pressure drop across the turbine. Different fuel pressure has been tested, varying the operating parameters and the position of the pressure sensors inside the chamber. For each configuration, a detailed analysis of the mean pressure trends and cycle-to-cycle variation was carried out and will help optimize the system in the following tasks of the project. The experimental methodology described can be used to better investigate the physics of Pressure Gain Combustors and allow complete exploitation of their potentiality in terms of work extracted, resource consumption, and pollutant emission.