静止可燃气热射流爆震起爆块结构自适应网格加密数值模拟

Numerical Simulation of Detonation Initiation in Quiescent Combustible Mixtures with Block-Structured Adaptive Mesh Refinement Method

关键词:  自适应网格加密  热射流  爆震起爆  二次壁面反射  双三波点碰撞 

Key words:  Adaptive mesh refinement  Hot jet  Detonation initiation  Two-time wall reflections  Two triple-wave points collision

摘要:

为了深入认识理解静止可燃气热射流爆震起爆的机理过程,采用块结构自适应网格加密方法的开源程序AMROC,进行二次开发,在LINUX系统中建立小型集群并行计算系统,应用于静止可燃气热射流爆震起爆过程高效精细数值模拟,并根据流场特性划分三个阶段进行分析。结果表明:对于一定条件下的热射流,静止可燃气中的热射流爆震起爆对壁面的依赖性很强,正是通过壁面的反射作用形成局部爆震燃烧；通过左壁面和上壁面的有效二次壁面反射,上壁面处的局部爆震燃烧进一步增强,强化的局部爆震燃烧逐渐向整个等直管道中传播；上壁面和下壁面的局部爆震燃烧同时形成之后,双三波点结构在管壁中来回碰撞碰,形成周期性的稳定爆震燃烧。 

Abstract:

In order to obtain a profound understanding of the mechanism of detonation initiation in quiescent combustible mixtures using hot jet, further development for the open-code program AMROC of block-structured adaptive mesh refinement method was adopted for fine structure numerical simulation of detonation initiation in quiescent combustible mixtures with hot jet. Simulations were conducted on a small-scale nested parallel computation system on LINUX platform. The initiation process was specified as three stages and their flow field characteristics were analyzed. Results indicate that for hot jets in certain conditions the initiation process is strongly dependent on the walls of the tube in which reflecting effects induce local combustion and detonation subsequently. With two-time reflection on the head face and the upper wall of the tube, detonation near the upper wall is amplified and spread into the whole channel. When local detonation is formed at both the upper and lower walls, two triple-wave points are generated, and collide between the upper and lower walls inside the tube.Thus a stable periodic detonation wave is formed. 