Design and ignition characteristics of kerosene/oxygen pre-detonator and kerosene/air hot-jet schemes under rotating detonation engine

The Rotating Detonation Engine (RDE) exhibits significant advantages including a simple configuration, high specific impulse, compact size, and elevated heat release rate. However, initiating detonation with liquid aviation kerosene remains challenging due to its relatively high ignition energy requirements. This study presents the design of a kerosene/oxygen pre-detonator, incorporating a dual-stage axial cyclone, an ignition cavity, and a deflagration-to-detonation transition (DDT) chamber. Experimental investigations were conducted to characterize the detonation combustion behavior of the pre-detonator. Due to the effects of fuel atomization and detonation transition dynamics, the pre-detonator demonstrated optimal performance within an equivalence ratio range of 0.6–0.7, achieving a detonation wave pressure of up to 6.5 MPa and a wave velocity around 1700 m/s. As the outlet pressure decreased, the required DDT length increased and the wave energy declined; nonetheless, detonation waves with pressures near 2.0 MPa were still achieved. Building on the pre-detonator configuration, a turbulent flow annulus was introduced to enable successful initiation using a kerosene/air mixture. Under this configuration, detonation wave pressures of approximately 1.0 MPa were realized. In low-pressure outlet environments, the kerosene/air ignition system operated in a Hot-jet mode. Both the pre-detonator and Hot-jet modes were employed to initiate the RDE. Results demonstrate that both ignition strategies can successfully initiate rotating detonation waves. The pre-detonator method facilitates rapid initiation through high-energy detonation wave impact, decoupling, and transition, leading to the formation of a stable rotating detonation wave. In contrast, the Hot-jet method relies on the gradual accumulation of compression waves to establish stable detonation. Compared to the Hot-jet approach, the pre-detonator significantly reduces the time required for detonation establishment. However, once the RDE reaches steady-state operation, the detonation characteristics converge regardless of the ignition method.