采用一维湍流模型对瞬态煤粉气化火焰的数值模拟

Numerical Simulation of Instantaneous Coal Gasification Flames With One Dimension Turbulence Model

煤的气化火焰中,湍流脉动与煤颗粒气化过程间存在着强烈的相互作用。为了在全尺度范围内直接模拟这种相互作用,本文采用一维湍流模型(ODT)与煤的气化过程相耦合,在Kolrnogorov尺度下对煤气化火焰区域进行数值模拟,得到了二维平面煤气化火焰的瞬态结构。模拟结果表明,大尺度涡团能够显著改变火焰的结构,并诱发局部小尺度涡团的产生。颗粒粒径决定湍流-气化过程作用的尺度范围,粒径较小的煤颗粒容易受到气体温度和速度脉动的影响,从而改变其运动轨迹和气化反应进程。

There is a strong interaction between turbulence fluctuation and coal gasification process in the coal gasification flames. In order to directly capture this interaction through full-scale range, one- dimensional turbulence model （ODT） coupled with coal gasification process was adopted.Numerical simulation up to Kolmogorov scales were carried out to predict the instantaneous two-dimensional coal gasification flames. The simulation results show that large-scale vortex have significant effects on the flame structure as well as flow field. In addition, more small eddies were produced under such effect. Particle size dominates the scales of turbulence-gasification interactions. Smaller size coal particles were more sensitive to fluctuations of gas temperature and velocities. As a result, the gasification processes of these particles have more chance to be changed.