微波瓣燃烧器中流向涡混合数值研究

Numerical study of streamwise vortex formation in micro-lobed burners

为了检验波瓣喷管下游流向涡能否促进燃烧,对尺度为毫米量级的微波瓣喷管混合燃烧器中流向涡的行为进行了数值模拟研究.研究发现,微波瓣喷管燃烧器中远没有微波瓣喷管混合器中非常强烈的流向涡形成和发展,造成差别的根本原因在于本该形成流向涡的主次气流接触界面变成了燃烧火焰的锋面,燃烧反应气流体积的急剧膨胀使流向涡环量迅速耗散衰减.另外,流场计算结果显示在4波瓣和8波瓣微喷管燃烧器中主次流接触初期有较明显的流向涡生成、发展和很快消失,而在12波瓣微喷管燃烧器中基本没有明显的流向涡形成和发展.但是,对比模拟表明,在同样边界条件下12波瓣微喷管混合器中却有非常明显的流向涡的形成和发展.

Numerical study was conducted for streamwise vortex formation of microlobed burner and micro-lobed mixer in the dimension of millimeter to investigate the possibility of burning intensification made by streamwise vortices. It was found that though the beginning, developing and disappearing of streamwise vortex are evident in the 4-lobed burner and the 8-lobed burner, the intensity and affecting range of the streamwise vortex are much less than that in the corresponding micro-lobed mixers. The streamwise vortices are not visible in the 12-lobed burner; by contraries the beginning, developing and disappearing of streamwise vortex can be seen evidently in the same 12-lobed mixer. The reason for streamwise vortex development difference in both micro-lobed burners and micro-lobed mixers is that the burning makes the gas products expand rapidly and the initial streamwise circulation decay quickly.