DNS analysis of boundary layer flashback in turbulent flow with wall-normal pressure gradient
DNS analysis of boundary layer flashback in turbulent flow with wall-normal pressure gradient
复制标题
壁面法向压力梯度湍流边界层闪回的DNS分析
DOI：
10.1016/j.proci.2020.06.004
复制
发表时间：
2021
影响因子：
3.4
通讯作者：
Bailey J
中科院分区：
文献类型：
--
作者：
Bailey J
燃烧系统中涡流的存在使其边界层回火特性发生显著变化。在这项研究中的旋流的两个方面进行了研究：旋流产生的壁面法向压力梯度的效果，和平均流动方向和火焰传播方向之间的错位的效果。分析采用直接数值模拟（DNS）的贫燃料预混氢-空气火焰在湍流平面通道流与摩擦雷诺数为180。通过施加壁面法向压力梯度剖面来研究涡流对闪回过程的影响。DNS数据的分析显示了流场和火焰拓扑结构的差异如何导致总体回火速度的差异。流动和传播方向的不对准导致火焰形状统计的不对称性，因为边界层中的高速流体的条纹以一定角度劈裂到火焰前缘中，从而增加远离壁的火焰表面密度。由于火焰前缘的密度分层，旋流在沿旋流环形流的中心体沿着回火期间对湍流火焰前缘具有稳定作用，并产生湍流消耗速度的降低。然而，旋流也建立了一个流体静压差，驱动火焰向前，净效果是，回火速度增加。流体静力学效应的主导地位，促使发展相对简单的建模的效果，旋流的回火速度。考虑无粘动量平衡和约束效应的模型，充分描述了在以前的实验研究中观察到的闪回速度的旋流效果。
The presence of swirl in combustion systems produces a marked change in their boundary layer flashback behaviour. Two aspects of swirling flow are investigated in this study: the effect of the swirl-generated wall-normal pressure gradient, and the effect of misalignment between the mean flow direction and the direction of flame propagation. The analysis employs Direct Numerical Simulation (DNS) of fuel-lean premixed hydrogen-air flames in turbulent planar channel flow with friction Reynolds number of 180. The effect of swirl on the flashback process is investigated by imposing a wall-normal pressure gradient profile. Analysis of the DNS data shows how the resulting differences in flow field and flame topology contribute to the differences in the overall flashback speed. Misalignment of the flow and propagation directions leads to asymmetry in the flame shape statistics as streaks of high velocity fluid in the boundary layer cleave into the flame front at an angle, yielding an increase in flame surface density away from the wall. Swirl has a stabilising effect on the turbulent flame front during flashback along the centre-body of a swirling annular flow due to the density stratification across the flame front, and produces a reduction in turbulent consumption speed. However the swirl also sets up a hydrostatic pressure difference that drives the flame forward, and the net effect is that the flashback speed is increased. The dominance of hydrostatic effects motivates development of relatively simple modelling for the effect of swirl on flashback speed. A model accounting for the inviscid momentum balance and for confinement effects is presented which adequately describes the effect of swirl on flashback speed observed in previous experimental studies.
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DOI：
10.1115/1.4034237
发表时间：
2017-02-01
影响因子：
1.5
作者：
Hoferichter, Vera;Hirsch, Christoph;Sattelmayer, Thomas
通讯作者：
Sattelmayer, Thomas
漩涡火焰边界层闪回
DOI：
--
发表时间：
2016
期刊：
影响因子：
--
作者：
D. Ebi
通讯作者：
D. Ebi
预混旋流火焰回火过程中惯性力在火焰流相互作用中的作用
影响因子：
3.4
作者：
R. Ranjan;D. Ebi;N. Clemens
通讯作者：
N. Clemens
影响因子：
4.4
作者：
Ebi, Dominik;Clemens, Noel T.
通讯作者：
Clemens, Noel T.