Numerical study on ethylene-air continuous rotating detonation in annular combustors with different widths

To investigate the impact of combustor width on continuous rotating detonation (CRD) fueled by ethylene and air, a series of 3D simulations are conducted by changing the inner cylinder radius of an annular combustor while retaining the same outer cylinder radius. The results show that the CRD wave propagates more steadily and faster as the combustor width increases. The high-temperature zone at the backward-facing step preheats the propellants and contributes to the steady propagation of the CRD wave in 25- and 30-mm wide combustors. The highest and the lowest velocities are obtained in the 30- and 15-mm wide combustors at, respectively, 1880.27 and 1681.01 m/s. On the other hand, the average thrust decreases as the combustor width increases. The highest thrust is obtained in the 15-mm wide combustor while the lowest is in the 30-mm wide combustor, at 758.06 and 525.93 N, respectively. Nevertheless, the thrust is much more stable in the 25- and 30-mm wide combustors than in the 15- and 20-mm wide combustors.