Effect of ozone sensitization on the reflection patterns and stabilization of standing detonation waves induced by curved ramps

Standing detonation engines are a promising detonation-based propulsion technology. The most commonly studied standing detonation configuration involves a straight-sided wedge that induces an oblique detonation wave. A recently introduced standing-detonation-engine concept entails a curved ramp that leads to formation of a curved detonation wave. The continuous compression or expansion induced by the ramp curvature can have significant influence on the flow characteristics and wave patterns of the detonation wave, offering greater flexibility in engine design than conventional wedge geometries. This study aims to further explore this relatively new standing-detonation-engine concept by examining the effect of ignition promoters, namely ozone, on the flow characteristics and reflection patterns of curved detonation waves induced by convex or concave ramps inside a confined combustion chamber. Simulations are performed using a positivity-preserving and entropy-bounded discontinuous Galerkin method with curved elements to exactly represent the ramp geometries. In the context of wedge-induced oblique detonation waves, ozone addition has been found to decrease the initiation length and lead to a smoother shock-detonation transition. This can then attenuate the detonation and reduce stagnation-pressure losses, thus improving the potential propulsion performance. In the context of detonation waves induced by curved ramps, although ozone addition similarly shortens the initiation zone, the curvature of the ramp introduces additional effects that can amplify or counteract both the ozone-induced contraction of the initiation zone and the aforementioned detonation attenuation. Furthermore, specific examples are presented wherein ozone addition changes the type of reflection pattern (e.g., regular reflection, stationary Mach reflection, and non-stationary Mach reflection).