Numerical study on unsteady structure of oblique detonation wave induced by a finite cone

Axisymmetric conical structures, as a common configuration, induce oblique detonation waves exhibiting significantly greater structural complexity compared to those generated by sharp wedges. Numerical simulations of oblique detonation waves induced by a finite cone were performed using the open-source code OpenFOAM, with analysis conducted on post-detonation flow fields, wavefront structure, and detonation cell structures. The numerical results show that under the effect of the finite cone the flow field behind the detonation wave is successively influenced by Taylor-Maccoll flow and Prandtl-Meyer expansion waves. The pressure and Mach number along the streamlines at different positions on the detonation wave front exhibit oscillatory changes with the influence of these two physical processes and triple points on oblique detonation surfaces, and then tend to stabilize. Depending on the different post-detonation flow field, the detonation wave front structure is divided into four sections: smooth ZND (Zel’dovich-Neumann-Döring)-like structure, single-headed triple points cell-like structure, dual-headed triple points cell structure and dual-headed triple point structure influenced by Prandtl-Meyer. The shock pole curve theory is used to analyze the wave structures. It is found that the upstream-facing triple points exhibits higher detonation intensity, i.e., higher Mach number and pressure, compared to the downstream-facing triple points in dual-headed triple points structure. Finally, based on the above analysis, triple point traces are recorded to obtain four different cell structures: smooth planar structure, parallel line structure, oblique rhombus structure, and irregular oblique rhombus structure.