Experimental investigation of turbulent flames in uniform dispersions of ethanol droplets
Experimental investigation of turbulent flames in uniform dispersions of ethanol droplets
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DOI：
10.1016/j.combustflame.2017.01.014
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发表时间：
2017-05-01
影响因子：
4.4
通讯作者：
Mastorakos, E.
中科院分区：
文献类型：
--
作者：
Kariuki, J.;Mastorakos, E.
本文利用一台带导向器的本生灯，研究了总当量比为0.62、0.72和0.82时，乙醇液滴均匀混合物中的湍流火焰。OH* 化学发光的成像和OH PLIF和米氏散射的同时成像，两者都在5 kHz下，以及CH 2 O燃料PLIF在5 Hz下的成像，用于获得瞬时和时间平均图像、时间序列和火焰表面密度和曲率的2-D估计。1-D PDA和LDA测量用于获得液滴尺寸和速度统计。在φ（0 v）= 0.62时，火焰呈圆柱形，随着燃料装载量的增加，火焰变为圆锥形，以获得更高的φ（0 v）。通常观察到较大的液滴比较小的液滴具有较低的平均和RMS轴向速度。液滴尺寸分布的轮廓表明下游液滴数密度降低以及向较大液滴直径的转变。观察到的火焰结构是相对平滑的位置附近的燃烧器出口，并变得更加扭曲的距离下游。通常，观察到液滴与OH的低至中等区域一致。偶尔，液滴似乎穿透火焰前锋，并在中高OH区域检测到。这尤其发生在下游位置处，在该位置处火焰横跨射流闭合，在垂直于火焰前缘的方向上没有观察到超过2 mm的显著平均液滴穿透。测量结果表明，随着下游距离和燃料装载量的增加，火焰表面密度逐渐减小，火焰前缘曲率增大。平均液滴蒸发速率的估计值随着下游距离和0，的增加，因为液滴出现在较高的平均进展变量区域。这里报道的测量是有用的模型验证火焰传播在稀喷雾。(C)2017作者由爱思唯尔公司出版代表燃烧研究所
A turbulent flame in an ethanol droplet-laden uniform mixture is investigated at overall equivalence ratios (phi(0v)) of 0.62, 0.72 and 0.82, using a piloted Bunsen burner. Imaging of OH* chemiluminescence and simultaneous imaging of OH PLIF and Mie scattering, both at 5 kHz, and imaging of CH2O-fuel PLIF at 5 Hz, were used to obtain instantaneous and time-averaged images, temporal sequences and 2-D estimates of flame surface density and curvature. 1-D PDA and LDA measurements were used to obtain droplet size and velocity statistics. At phi(0v) = 0.62, the flame takes a cylindrical shape, and changes to a cone shape with increasing fuel loading to obtain higher 00,. Larger droplets are generally observed to have lower average and RMS axial velocities than smaller droplets. Profiles of droplet size distributions indicate a decreasing droplet number density downstream together with a shift to larger droplet diameters. The flame structure is observed to be relatively smooth at locations near the burner exit, and becomes more contorted with distance downstream. In general, droplets are observed to coincide with low-to-intermediate regions of OH. Occasionally, droplets appear to penetrate the flame front, and are detected in regions of intermediate-to-high OH. This occurs particularly at the downstream locations where the flame closes across the jet, with no significant averaged droplet penetration observed past 2 mm in the direction normal to the flame front. Measurements show a gradual reduction in flame surface density and higher flame front curvature with both distance downstream and increasing fuel loading. Estimates of the average droplet evaporation rate increase with both distance downstream and 0,,, as droplets appear in higher mean progress variable regions. The measurements reported here are useful for model validation of flame propagation in dilute sprays. (C) 2017 The Authors. Published by Elsevier Inc. on behalf of The Combustion Institute.