部分预混对向流火焰拉伸变形研究

Study on Tensile Deformation of Partially Premixed Counterflow Flame

本文为了研究部分预混当量比φ_p对对向流火焰结构的影响规律、探究对向流火焰中心拉伸形变的原因,分别构建了圆形对向流火焰和线形对向流火焰测试系统,并进行了与之对应的仿真工作。研究显示,部分预混对向流火焰由动力火焰和扩散火焰两部分组成,呈现典型的双火焰结构;随着φ_p的降低,动力火焰与扩散火焰之间的间距逐渐增加。在较低的φ_p下,圆形对向流火焰存在明显的拉伸变形现象,动力火焰中轴线附近区域向预混可燃气来流方向显著凸起。火焰中心区域的热量堆积导致径向温度分布不均、局部火焰传播速度与来流速度的不均衡,是造成动力火焰拉伸凸出的根本原因。相对而言,线形对向流火焰通过强化Y轴散热消除了动力火焰中心区域的热量堆积现象,故火焰拉伸变形现象并不明显。

In order to study the influence of the partially premixed equivalence ratio φp on counterflow flame structure and to study the reason of tensile deformation in counterflow flame center, cylinder coun- terflow flame and linear counterflow flame test systems are built, and the corresponding simulation work is done. Research shows that premixed flame and diffusion flame constitute partially premixed counterflow flame which has a typical double flame structure ; And with the decrease of φp, the gap between premixed flame and diffusion flame increases. When φpiS small, cylinder counterflow flame has obvious tensile de- formation, and the zone near central axis of premixed flame bulges towards flow direction of premixed combustible gas. Heat accumulation of the flame center leads to uneven distribution of radial temperature and imbalance between local flame propagation velocity and incoming velocity, which is a basic reason for tensile deformation of premixed flame. Comparatively, linear counterflow flame eliminates the heat accu- mulation in premixed flame center by intensifying heat dissipation of y - axis, so tensile deformation is not obvious.