等离子点火器三维燃烧流场的大涡模拟

Large eddy simulation of 3D combustion flow field in plasma generator

针对等离子点火器的三维燃烧流场进行了大涡模拟.对亚格子项采用Smagorinsky＿Lilly模式,湍流燃烧采用涡耗散模型,压力—速度耦合采用SIMPLE算法,空间离散采用中心差分格式,时间离散采用二阶精度的隐式差分格式.得到了燃烧反应流特性参数的分布、湍流燃烧的瞬态发展变化过程以及在拟序结果影响下燃烧的特征.大涡模拟结果表明,复杂的漩涡结构与化学反应的相互作用控制和强化了燃烧过程;在燃烧的充分发展阶段,大涡模拟能更好地反映流场的各项异性和合理的湍流统计物理量的分布,描述了湍流拟序结构对湍流燃烧的影响.

Three-dimensional combustion fluid flow of plasma generator was simulated by large eddy simulation (LES) using eddy dissipation combustion model closure. The Smagorinsky-Lilly sub-grid mode was used to model motions of small-scale structures. During the numerical simulation, the SIMPLE algorithm was applied. The central differential spatial discretization scheme and the second order accuracy finite difference scheme for the temporal discretization were used. Transient distributions of the characteristic parameters and the transient evolution process of coherent structures were given in the turbulent combustion reacting flow field. The results of LES show how the coherent structures affect diffusion of fuel in the plasma generator, and the interaction between vortical structures and chemical reactions controls and enhances the combustion. It is also found that the results of LES are better at indicating the anisotropic and the turbulent statistics parameters of the flow than those of a model at the fully developed period of the flame within the combustion flow field.