摘要:
轴对称锥体结构作为较常见的构形,其诱导的斜爆轰波比尖楔具有更复杂的结构。基于开源代码OpenFOAM对有限长锥体诱导的驻定斜爆轰波进行了数值模拟,并对爆轰波后流场、波阵面结构和爆轰胞格结构进行了讨论。结果表明,在有限长锥体结构的影响下,爆轰波后流场先后受到Taylor-Maccoll流动和Prandtl-Meyer膨胀波的影响。爆轰波阵面不同位置流线上的压力和马赫数在这两种物理过程及波阵面三波结构的影响下,发生震荡变化,随后趋于稳定。在不同波后流场的影响下,爆轰波阵面结构呈现四种不同的结构:类ZND的光滑结构、类胞格的单三波点结构、胞格的双三波点结构和Prandtl-Meyer影响的双三波点结构。借助于激波极曲线理论对三波点附近的波系进行了分析,发现在双三波点结构中,面向来流的三波点具有比面向下游的三波点具有更强的爆轰强度,即更高的马赫数和压力。最后,结合上述分析,绘制了爆轰波阵面的三波点轨迹,得到四种不同的胞格结构:光滑平面结构、平行线结构、斜菱形结构、无规则的斜菱形结构。
Abstract:
The axisymmetric cone, as a common configuration, is known to induce oblique detonation waves with a more complex structure compared to a wedge. Numerical simulations of the oblique detonation wave formed by a finite cone were conducted using the open-source code OpenFOAM, followed by discussions on the post-detonation flow field, detonation wave front structure, and detonation cell structure. The numerical results show that with the influence of the finite cone the post- detonation flow field is affected successively 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-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. 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 through shock polar analysis of wave systems near triple points. In conclusion, 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.