Turbine Integration in a RDE for Hydrogen-Based Power Generation

One possible application for rotating detonation engines (RDE) is power generation. The energy conversion from thermal to mechanical and finally electrical energy is a challenge due to the specific RDE characteristics. The main problems are the unsteady combustion process, the presence of shock waves and vibrations, as well as the very high combustion temperatures, which often lead to limited performing times. Furthermore, any additional flow resistance, such as a turbine, leads to an increase of the pressure inside the RDE and influences the detonation conditions. This paper presents the results and observations of an experimental water-cooled (rotating detonation combustor) RDC operated with H2 and air (equivalence ratio close to φ ~ 1). For H2 mass flows between 1 g/s and 2 g/s, stable single rotation detonation wave modes (SRDW) with a test duration of over 90 s are observed in hot fire tests. The used cooling water is injected downstream near the combustion chamber to reach moderate temperature conditions in the exhaust flow. A diffuser chamber is connected to the annular combustion chamber of the RDC, which directs the exhaust gas flow into a pipe (di = 82 mm). The exhaust gas flow can then be directed either to a bypass (start-up) or to a turbine (operation). Finally, a simple single-stage turbine, a gearbox, and a generator are used to convert the energy from the pressure gain combustion into electrical energy. Runtimes of 90 s (RDE) with 60 s of turbine operation are presented in this work.