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

Abstract

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.