基于LES-FGM方法的部分预混湍流燃烧中间组分模拟

Modelling Intermediate Species in Partially Premixed Turbulent Combustion Based on the LES⁃FGM Method

基于FGM建表燃烧模型对德国达姆施塔特工业大学的MRB部分预混湍流火焰开展大涡模拟,并对比研究了预混和部分预混FGM建表方法对模拟的影响.结果表明,不同建表方法对MRB火焰结构、速度分布和主要组分分布等影响较小,但部分预混建表能显著提升中间组分CO和H_(2)的模拟可靠性.其根本原因是部分预混建表使用了对冲火焰模型,能够充分引入燃空混合过程对中间组分的影响.通过添加额外的组分输运方程可提升预混火焰建表对中间组分模拟的可靠性,且前人提出的拉伸作用在该火焰中影响较小.该研究为基于建表方法的部分预混湍流燃烧准确模拟提供了重要参考.

The LES of partially premixed turbulent flame MRB in TU Darmstadt was conducted based on the flamelet⁃tabulated combustion model FGM,and effects of premixed and partially premixed tabulations on the modelling results were studied.The results show that,different methods of tabulation exhibit limited influences on the predictions of the flame structure,velocity,and major species,but using a partially premixed tabulation largely improves the reliability of modelling intermediate minor species CO and H2.The underlying reason lies in a better inclusion of the fuel⁃air mixing effects through the partially premixed tabulation,which is built based on laminar counter⁃flow flames.Adding extra transport equations for the intermediate species improves the pre⁃dictions of intermediate species,especially given a premixed tabulation adopted;meanwhile,the stretch effects in this turbulent flame are ignorable.The results are significant to guide the high⁃fidelity simulation of partially premixed turbulent flames based on the flamelet⁃tabulated combustion model.