基于LES的非稳态火焰面/反应进度变量方法模拟部分预混抬举火焰

Simulation of Partially Premixed Lifted Flame Based on Unsteady Flamelet/Progress Variable Approach of LES

关键词:  大涡模拟  非稳态  反应进度变量  抬举火焰  局部熄火

Key words:  Large eddy simulation  Unsteady  Progress variable  Lifted flame  Local extinction

摘要:

为了描述部分预混燃烧的火焰机制，捕捉燃烧现象中的非稳态效应，采用大涡模拟与非稳态火焰面/反应进度变量方法相结合来模拟湍流部分预混燃烧抬举火焰，并将计算结果与实验测量值进行了对比研究。结果表明基于大涡模拟的非稳态火焰面/反应进度变量方法捕捉到了湍流部分预混燃烧中的火焰抬举现象，计算得到的火焰抬举高度大致为35，和实验测量值完全一致。同时采用各热力学参数在混合分数空间的分布来研究部分预混抬燃烧中具有非稳态燃烧特性的局部熄火现象。各不同截面上的燃烧热力学参数与实验测量值吻合较好，说明采用该方法能比较真实地反映湍流部分预混燃烧的火焰机制。

Abstract:

In order to describe the flame mechanism in partially premixed combustion and capture the unsteady effect of combustion phenomenon，an unsteady flamelet/progress variable approach combining large-eddy simulation was applied in simulating a turbulent partially premixed lifted flame，and then taking the calculation values comparing with experiment measuring results. It is indicated that results of unsteady flamelet progress/variable combining large-eddy simulation have captured lifted flame phenomenon in the turbulent partially premixed combustion，and the lift-off height of calculation is about 35，lift-off height by experiment measurment is also 35. At the same time，analyse the unsteady combustion characteristic phenomenon of local extinction by mean of thermochemical quantities in mixture fraction space. Thermochemical quantities in different sections by calculation agree reasonably well with the experiment measuring results. It is indicated that combining large-eddy simulation with unsteady flamelet progress/variable could correctly reflect flame mechanism existing in turbulent partially premixed combustion.