Experimental demonstration of detonation initiation in a rotating detonation engine by laser ignition

Kurzfassung

Rotating detonation engines (RDEs) are considered promising next-generation propulsion systems, and several ignition methods have been employed to start them. Although laser ignition has attracted considerable attention and has been applied in various aerospace applications, its application to RDEs remains largely unexplored. Therefore, this study aims to demonstrate the feasibility of laser ignition for RDEs. A series of experiments was conducted using laser ablation ignition (LAI) and laser-induced spark ignition (LSI) with gaseous hydrogen and oxygen over total mass flow rates of 17.1–61.5 g/s and equivalence ratios of 0.74–1.89. Ignition success was achieved in all 29 test cases without significant structural degradation of the ignition system or combustion chamber. Detonation initiation success was evaluated using two criteria: a non-dimensional propagation velocity of the rotating chemiluminescence pattern greater than 0.6 and a non-dimensional maximum fill height of the unburned gas greater than 3. In the LAI configuration, both criteria were satisfied at four operating conditions corresponding to total mass flow rates of 32.1–45.0 g/s and equivalence ratios of 0.85–0.98 and 1.32. In the LSI configuration, the non-dimensional velocities were comparable to those in the LAI cases over the tested range of total mass flow rates, and both criteria were satisfied at a total mass flow rate of 35.6 g/s and an equivalence ratio of 0.97. Therefore, successful operation of the laser-ignited RDE was demonstrated for both LAI and LSI under the respective operating conditions.