Effect of rotating detonation back-propagation on an axial flow compressor under different relative rotating modes

In order to reveal the effect mechanism of rotating detonation back-propagation on an axial flow compressor, the back-propagation process and its disturbance on the compressor were investigated using three-dimensional numerical simulations, and the critical back-propagating pressure oscillation ratio that the compressor could withstand was determined. In this paper, steady simulations of the compressor were first conducted to obtain its outlet parameters, which were subsequently used to define the inlet boundary conditions for the transient simulation of rotating detonation back-propagation. Then, the back-propagating pressure histories were applied to the outlet boundary of the compressor transient simulation. The main conclusions are summarized as follows. The compressor rotor speed governs the back-propagation resistance ability by modulating the intensity of the compression wave system and normal shock waves within blade passages. Higher rotor speeds intensify passage wave systems, thereby enhancing the ability of the compressor to withstand back-propagating disturbances. Therefore, a higher rotor speed is more conducive to maintaining stable compressor operation under back-propagating disturbances. Furthermore, the relative rotational direction between the detonation wave and the compressor rotor fundamentally alters the back-propagation disturbance mechanism. In the counter-rotating mode, the relative propagation direction enhances the blocking effect of the blades on the back-propagating pressure wave, while the increased relative velocity distributes disturbances across more passages at a lower intensity. These combined factors reduce the localized impact on individual blade passages, making the counter-rotating mode more conducive to maintaining stable compressor operation under back-propagating disturbances. Additionally, the critical pressure oscillation ratio of the compressor under back-propagation increases with rotor speed and is consistently higher in the counter-rotating mode. This critical ratio depends on two primary factors: the wave system intensity (dependent on rotor speed) and the relative propagation characteristics (dependent on the relative rotating mode), of which the former is dominant.