基于假定映射函数方法的升力H2/N2湍流射流火焰条件矩闭模型

IF 1.5 Q3 ENGINEERING, CHEMICAL
A. E. Sayed, R. Fraser
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引用次数: 0

摘要

采用条件矩闭包(CMC)和假定映射函数(PMF)方法对条件混合和速度统计建模进行了研究。使用规定的参考场,PMF方法产生混合分数的假定概率密度函数(PDF),然后使用该函数以完全一致的方式关闭条件标量耗散率(CSDR)和条件速度。将这些闭包应用于提升的火焰,并将结果与之前在共流温度范围内使用β- pdf闭包获得的结果进行比较()。PMF的结果与β-PDF的结果一致,并且与测量结果比较好。混合分数和物理空间的运输预算以及稳定高度之前的激进历史表明稳定机制容易受到影响。与之前的β-PDF计算一样,在“最活跃”混合物分数附近自燃仍然是足够高的控制机制。当PMF通过预混合火焰传播预测稳定性时,观察到β-PDF预测的偏离。这一结论是基于观察到贫混合气在稳定化高度之前的预热区被下游燃烧混合气加热。伪源,这源于不一致的CSDR建模,进一步研究。研究结果表明,它们的影响很小,但不可忽略,尤其是在火焰区。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Conditional Moment Closure Modelling of a Lifted H2/N2 Turbulent Jet Flame Using the Presumed Mapping Function Approach
A lifted hydrogen/nitrogen turbulent jet flame issuing into a vitiated coflow is investigated using the conditional moment closure (CMC) supplemented by the presumed mapping function (PMF) approach for the modelling of conditional mixing and velocity statistics. Using a prescribed reference field, the PMF approach yields a presumed probability density function (PDF) for the mixture fraction, which is then used in closing the conditional scalar dissipation rate (CSDR) and conditional velocity in a fully consistent manner. These closures are applied to a lifted flame and the findings are compared to previous results obtained using β-PDF-based closures over a range of coflow temperatures ( ). The PMF results are in line with those of the β-PDF and compare well to measurements. The transport budgets in mixture fraction and physical spaces and the radical history ahead of the stabilisation height indicate that the stabilisation mechanism is susceptible to . As in the previous β-PDF calculations, autoignition around the “most reactive” mixture fraction remains the controlling mechanism for sufficiently high . Departure from the β-PDF predictions is observed when is decreased as PMF predicts stabilisation by means of premixed flame propagation. This conclusion is based on the observation that lean mixtures are heated by downstream burning mixtures in a preheat zone developing ahead of the stabilization height. The spurious sources, which stem from inconsistent CSDR modelling, are further investigated. The findings reveal that their effect is small but nonnegligible, most notably within the flame zone.
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来源期刊
Journal of Combustion
Journal of Combustion ENGINEERING, CHEMICAL-
CiteScore
2.00
自引率
28.60%
发文量
8
审稿时长
20 weeks
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