Large Eddy Simulation of Backward-Facing Stop Flow with Application to Coaxial Jet Combustors.
Large Eddy Simulation of Backward-Facing Stop Flow with Application to Coaxial Jet Combustors.
复制标题
向后停止流的大涡模拟及其在同轴喷射燃烧器中的应用。
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
P. Moin
中科院分区：
文献类型：
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作者：
P. Moin
摘要：对平面后台阶和同轴射流燃烧室两种大规模分离流场进行了大涡模拟。后向台阶的情况下，用于开发和验证的数值方法和亚网格尺度模型。在雷诺数5100和28000下进行了后向台阶模拟。这两种情况都与实验数据吻合得很好，低雷诺数的情况下，也是在良好的协议与DNS数据。两个版本的动态亚网格尺度模式以及经典的Smagorinsky模式进行了测试，发现它们之间的差异不大。同轴射流燃烧室模拟被用作研究火焰稳定性问题的第一步，称为贫油熄火。研究的重点是在燃烧室内的燃料和空气的夹带和混合，使用被动标量跟踪技术。在最初的研究中，化学反应和热释放的影响被忽略了。雷诺数为38000时的平均统计数据与实验数据吻合较好。非定常运动的动态图像显示富燃料流体的间歇性气穴穿过环形空气射流并被夹带在再循环区中。然而，发现更大的卷吸源是在燃烧室壁上的瞬时冲击点附近燃料射流的上游改向。
Abstract : Large eddy simulations (LES) have been performed for two massively separated flows: a planar backward-facing step and a coaxial jet combustor. The backward-facing step case was used to develop and validate both the numerical method and the subgrid-scale model. Backward-facing step simulations were performed at Reynolds numbers 5100 and 28000. Both cases agree well with experimental data; the low Reynolds number case is also in excellent agreement with DNS data. Two versions of the dynamic subgrid-scale model as well as the classical Smagorinsky model were tested and little difference was found among them. The coaxial jet combustor simulations were used as a first step to study the flame stability problem known as lean blow-out. The study focused on the entrainment and mixing of fuel and air within the combustion chamber, using a passive scalar tracking technique. Chemical reactions and the effects of heat release were ignored in this initial study. Mean statistics at Reynolds number 38000 are in good agreement with experimental data. A motion picture of the unsteady motion revealed intermittent pockets of fuel-rich fluid crossing the annular air jet and becoming entrained in the recirculation zone. A larger source of entrainment, however, was found to be the upstream redirection of the fuel jet near the instantaneous impingement point on the combustor wall.