Numerical and Experimental Studies on Curvature-Induced Behavior of Detonation Waves in an Annular Channel

Abstract

To elucidate the influence of curvature on the mechanism governing stable detonation waves, this study delves into the experimental and numerical exploration of gaseous detonations within an annular channel utilizing a 2H₂/O₂/3Ar mixture. The investigation encompasses both empirical observations of the cellular structure of the detonation wave through a soot-coated stainless-steel plate and numerical simulations employing advanced methodologies. To capture the intricacies of the detonation phenomenon, the second-order additive semi-implicit Runge–Kutta method and the fifth-order weighted essentially non-oscillatory (WENO) scheme are adeptly employed for discretizing the time and spatial derivatives, respectively. The underlying chemical reactions during detonation are meticulously modeled using a detailed reaction mechanism. The pressure and velocity contours unveiling a nuanced picture are extracted using a numerical analysis. The inner wall divergence effect emerges as a critical determinant, weakening the detonation strength and consequently yielding the larger cellular structures. Contrarily, the outer wall convergence effect significantly amplifies the strength yielding the smaller cellular structures. This intricate interplay causes the detonation velocity to increase progressively along the radial direction. Furthermore, near the inner wall the detonation wave manifests periodic phases of augmentation and attenuation, resulting in oscillations in both the velocity and the pressure. A granular scrutiny of the flow field finer attributes underscores the continuous regeneration and dissolution of triple points along the wave front. Notably, triple point regeneration predominantly occurs near the outer wall surface, while their dissipation is more proximate to the inner wall. In the context of the stable detonation wave, equilibrium between triple point regeneration and decay sustains a constant triple point count on the wave front. This pivotal equilibrium enables the self-sustaining propagation of detonation within the annular channel.