Performance analysis of a rotary inner wavy cylindrical surface in a small-scale rotating detonation engine at the early starting stage

This study parametrically investigates the effects of corrugation configuration, corrugation inclination to the axis, and wave number on the motion of a rotary inner wavy cylindrical surface in a small-scalerotating detonation engine at the early starting stage. A quasi-two-dimensional numerical analysis tool is developed to reveal the coupling between the detonation flowfields and the inner-surface motion. Itstheoretical basis is a transient lateral area-variational source term with two degrees of freedom, alongwith a two-step reaction model. The stochiometric hydrogen/oxygen mixture of p0 = 0.5 MPa and T0 = 300 K is injected into the combustor, of which the mean radius and height are separately 0.0159 m and 0.02 m. With the detonation wave propagating in the annular channel, the square-wave corrugation is proven to suppress the flow-around characteristics and promote the fluid transport along the groovesmore effectively than the sawtooth and sinusoidal corrugations. The ultimate rotational speeds of the sinusoidal, sawtooth, and square-wave corrugations are, respectively, 11.65, 8.25, and 30.23 rad·s-1 at t =1 ms. With the detonation wave inclined in the opposite direction to the corrugation, the flow-turning effects become obvious, indicating that the corrugation twisting mode is a critical design parameter. The time-averaged tangential force for θ = +10° exceeds those for θ = +5°, 0°, and -5° by 54.07%, 28.32%, and 105.8%, respectively. For θ = -10°, the time-averaged tangential force is close to zero. In addition, the increments in rotational acceleration and tangential force decrease with increasing wave number. The increase in the power extraction results in a drop in the exit Mach number and the specific impulse, which is quite similar to the turbine operation.