Direct numerical simulations of premixed and stratified flame propagation in turbulent channel flow
Direct numerical simulations of premixed and stratified flame propagation in turbulent channel flow
复制标题
湍流通道流中预混合和分层火焰传播的直接数值模拟
DOI：
10.1103/physrevfluids.3.110507
复制
发表时间：
2018
影响因子：
2.7
通讯作者：
Gruber A
中科院分区：
文献类型：
--
作者：
Gruber A
采用直接数值模拟的方法，研究了在充分发展的槽道湍流中，均匀的、燃料分层的氢气-空气混合气在上游的瞬时火焰传播(闪回)。结果表明，在两种情况下，火焰沿主体流动方向均保持稳定传播，燃料分层的发生对整体火焰形态和局部火焰特征均有影响。总体而言，当接近的反应物从均匀混合构型转变为分层混合构型时，平均火焰形状经历了突变。前缘位于近壁区的V型火焰面表征了非分层的均匀混合气情况，而前缘沿通道中心线向上传播的U型火焰面区分了燃料分层(近壁区燃料贫化，远离壁面燃料丰富)。湍流火焰刷子的特征厚度、起皱和置换速度在整个通道上都会发生相当大的变化，这是因为湍流和混合物的性质与通道壁面的距离有关。更具体地说，在燃料分层情况下，火焰从均匀混合气情况下的中等皱纹、薄火炬燃烧区域转变为更能代表加厚火焰燃烧区域的强烈皱纹火焰刷子。燃烧规律可能与卡洛维茨数有关，结果表明，在充分发展的槽道流动中，基于正则湍流()和化学反应()时间尺度的壁法向变化的异常槽道流动卡洛维茨数与有效的卡洛维茨数(卡洛维茨数)相比，后者是根据火焰附近的条件采样值从目前的DNS数据集中提取的。
Direct numerical simulations are performed to investigate the transient upstream flame propagation (flashback) through homogeneous and fuel-stratified hydrogen-air mixtures transported in fully developed turbulent channel flows. Results indicate that, for both cases, the flame maintains steady propagation against the bulk flow direction, and the global flame shape and the local flame characteristics are both affected by the occurrence of fuel stratification. Globally, the mean flame shape undergoes an abrupt change when the approaching reactants transition from an homogeneous to a stratified mixing configuration. A V-shaped flame surface, whose leading-edge is located in the near-wall region, characterizes the nonstratified, homogeneous mixture case, while a U-shaped flame surface, whose leading edge propagates upstream at the channel centerline, distinguishes the case with fuel stratification (fuel-lean in the near-wall region and fuel-rich away from the wall). The characteristic thickness, wrinkling, and displacement speed of the turbulent flame brush are subject to considerable changes across the channel due to the dependence of the turbulence and mixture properties on the distance from the channel walls. More specifically, the flame transitions from a moderately wrinkled, thin-flamelet combustion regime in the homogeneous mixture case to a strongly wrinkled flame brush more representative of a thickened-flame combustion regime in the near-wall region of the fuel-stratified case. The combustion regime may be related to the Karlovitz number, and it is shown that anominalchannel-flow Karlovitz number,, based on the wall-normal variation of canonical turbulence () and chemistry () timescales in fully developed channel flow, compares well with aneffectiveKarlovitz number,, extracted from the present DNS datasets using conditionally sampled values ofandin the immediate vicinity of the flame ().
登录
查看更多内容
薄反应区曲率引起的火焰拉伸模型的评估
影响因子：
4.4
作者：
E. Hawkes;Jacqueline H. Chen
通讯作者：
Jacqueline H. Chen
影响因子：
1.3
作者：
L. N. Khitrin;P. Moin;D. B. Smirnov;V. Shevchuk
通讯作者：
V. Shevchuk
影响因子：
1.3
作者：
Hoferichter, Vera;Hirsch, Christoph;Sattelmayer, Thomas
通讯作者：
Sattelmayer, Thomas
影响因子：
1.3
作者：
F. Biagioli
通讯作者：
F. Biagioli
DOI：
--
发表时间：
2006
期刊：
--
影响因子：
--
作者：
A. Gruber
通讯作者：
A. Gruber