Effects of ignition conditions on detonation wave evolution in a rotating detonation engine

In experiments, ignition conditions significantly influence detonation wave evolution during the initiation process of rotating detonation engines. Three-dimensional numerical simulations are conducted by solving the Navier-Stokes equations with a detailed chemical mechanism to investigate the effects of pre-detonator length, its axial installation position, and the ignition-source energy. The effects of pre-detonator axial position and ignition-source energy on stable-stage propagation direction reversal are investigated in detail. It is found that when the pre-detonator is installed near the headwall, restricted axial development strengthens the counterclockwise branch of the initial detonation wave after headwall interaction, producing a dominant pressure wave that guides the chaotic-stage evolution and establishes a counterclockwise mode. When it is installed farther downstream, both counter-propagating waves develop more symmetrically and a clockwise mode ultimately forms. Increasing ignition-source energy changes the final direction in a counterclockwise-clockwise-counterclockwise sequence because stronger initial waves promote detonation formation while stronger flow blockage suppresses reactant replenishment. Statistical analysis shows the chaotic stage duration decreases with increasing ignition pressure, indicating that higher ignition-source energy accelerates shock-fresh reactant interactions and wave-system evolution. This highlights the dominant role of ignition-source energy input during the initiation process. These findings provide new insights into the detonation wave evolution mechanism driven by initial ignition conditions, and offer theoretical guidance for choosing pre-detonator positions and ignition-source energy levels in engineering applications.