Experimental Study of a Cylindrical Rotating Detonation Torch for Scramjet Engines

To evaluate the applicability of a cylindrical rotating detonation (RD) combustor as a torch, combustion experiments were conducted in a scramjet model combustor. The results were compared with those obtained under low back pressure conditions to assess the performance of the RD torch. The torch had a combustion chamber with an inner diameter of 10 mm and a length of 173 mm, operating at a mass flow rate of 4.0 g/s and an equivalence ratio of 1.15. The total temperature, total pressure and Mach number of the main air were 641–719 K, 0.6 MPa and 2.8, respectively. Comparing the results under the two conditions, we concluded that the torch operated in detonation mode for up to 9.0 seconds under supersonic flow, even during main H2 combustion. The detonation wave speed was ranged from 2.07 to 2.14 km/s, corresponding to 84–86% of Chapman-Jouguet velocity and 156–160% of the sound speed in the burned gas. At a main H2 mass flow rate of 1.1 g/s, the scramjet combustor operated in scramjet mode, achieving both ignition and flameholding using the RD torch during scramjet-mode operation. Furthermore, we identified the effects of the main H2 combustion on the torch. Continuous propagation of detonation waves, consistent trends in the axial time-averaged pressure distribution even after the exhaust transitioned to a subsonic jet, pressure oscillations induced by the combustion in the cavity, and an increase in detonation wave speed all suggest new potential applications for the RD torch and directions for future work.