Simulation of Dilute Acetone Spray Flames with LES-CMC Using Two Conditional Moments
Simulation of Dilute Acetone Spray Flames with LES-CMC Using Two Conditional Moments
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使用 LES-CMC 使用两个条件矩模拟稀丙酮喷雾火焰
DOI：
10.1007/s10494-014-9565-1
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Stein O.T.
中科院分区：
文献类型：
--
作者：
Kronenburg;Stein O.T.
采用大涡模拟(LES)和条件矩闭合(CMC)相结合的方法对一系列湍流喷雾火焰进行了数值模拟。Ukai等人早先的一项研究。(程序燃烧。Inst.34(1)，1643-1650,2013)对于温度和速度分布的预测给出了合理的结果，但该方法的一些局限性变得明显。这些限制主要与混合分数空间的上限有关。为了提高LES-CMC模型的适用性，通过引入基于不同混合分数的两组条件矩，提出了一种双条件矩方法来考虑预蒸发燃料的存在。首先对两条件矩方法进行了非反应性测试。结果表明，喷雾蒸发在CMC单元内引起较大的条件波动，一组条件矩可能是不够的。对于第二组条件矩的解，动态地选择混合分数空间的上限，并通过两个条件矩之间的内插来估计CFD单元中相应的CMC解，这两个条件矩以区域内排放的水蒸气的量为权重。通过对混合分数空间上的条件矩进行积分，使用有界的β-FDF来确定标量的分布，从而给出单元滤波值。结果表明，大涡模拟和双条件矩方法得到的燃料浓度分布吻合较好。然后，将双条件矩方法应用于四种不同的火焰构型。LES单元数量和条件平均矩的比较表明，在计算域内液滴蒸发显著增加气相混合物分数的区域，这两组条件矩对于精确预测是必要的。无条件的温度分布清楚地表明，新的方法改善了平均温度的预测，特别是沿中心线的预测。此外，对温度场更好的预测提高了预测的平均液滴轴向速度的准确性。总体而言，对于所有四种情况，都发现与实验结果很好地吻合，并且该方法被证明适用于燃料蒸汽浓度范围相对较大的火焰。
Large-eddy simulations (LES) have been coupled with a conditional moment closure (CMC) method for the computation of a series of turbulent spray flames. An earlier study by Ukai et al. (Proc. Combust. Inst.34(1),1643–1650, 2013) gave reasonable results for the prediction of temperature and velocity profiles, but some limitations of the method became apparent. These limitations are primarily related to the upper limit in mixture fraction space. In order to enhance the applicability of the LES-CMC model, this paper proposes a two-conditional moment approach to account for the existence of pre-evaporated fuel by introducing two sets of conditional moments based on different mixture fractions. The two-conditional moment approach is first tested for a non-reacting test case. The results indicate that the spray evaporation induces relatively large conditional fluctuations within a CMC cell, and one set of conditional moments might not be sufficient. The upper limit of the mixture fraction space is dynamically selected for the solution of the second set of conditional moments, and the corresponding CMC solution in a CFD cell is estimated by interpolation between the two conditional moments weighted by the amount of vapour emitted within the domain. The cell-filtered value is given by integration of the conditional moment across mixture fraction space using a boundedβ-FDF for the distribution of the scalar. As a result, the fuel concentration profiles given by LES and the two-conditional moment approach are shown to agree well. Then, the two-conditional moment approach is applied to four different flame configurations. The comparison of LES cell quantities and conditionally averaged moments indicates that the two sets of conditional moments are necessary for accurate predictions in zones where gas phase mixture fraction is significantly increased by droplet evaporation within the computational domain. The unconditional temperature profiles clearly show that the new approach improves the predictions of mean temperature especially along the centerline. Also, the better predictions of the temperature field improve the accuracy of the predicted mean axial droplet velocities. Overall, good agreement with the experimental results is found for all four cases, and the methodology is shown to be applicable to flames with a relatively wide range of fuel vapour concentrations.
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影响因子：
4.4
作者：
V. N. Prasad;A. Masri;S. Navarro-Martinez;K. Luo
通讯作者：
V. N. Prasad;A. Masri;S. Navarro-Martinez;K. Luo
影响因子：
1.9
作者：
A. Masri;J. Gounder
通讯作者：
A. Masri;J. Gounder
影响因子：
4.4
作者：
M. Chrigui;J. Gounder;A. Sadiki;A. Masri;J. Janicka
通讯作者：
M. Chrigui;J. Gounder;A. Sadiki;A. Masri;J. Janicka
甘蔗渣锅炉的条件时刻闭合
DOI：
--
发表时间：
2007
期刊：
影响因子：
--
作者：
J. Rogerson;J. Kent;R. Bilger
通讯作者：
R. Bilger
DOI：
10.1063/1.857955
发表时间：
1991-07-01
期刊：
PHYSICS OF FLUIDS A-FLUID DYNAMICS
影响因子：
--
作者：
GERMANO, M;PIOMELLI, U;CABOT, WH
通讯作者：
CABOT, WH