中文摘要：

运用直接数值模拟方法对低速流动下的浮力反应羽流进行了三维数值模拟，分析了不同辐射通量下无量纲流场中近场浮力羽流的结构特性。在有重力场和燃烧释热的情况下，反应羽流自然演化生成周期性的大涡结构，随着辐射强度的增加，不仅对温度场有显著影响，同时还影响着羽流涡旋的发展及其下游三维涡旋结构之间的相互作用。同时，辐射并不破坏流场的对称性，有无辐射的流场涡旋结构均关于几何中心对称。

英文摘要：

Spatial direct numerical simulation （DNS） is used to study the near field dynamics of low-speed buoyant reactive plumes. The structure characteristics of non-dimensional flow field of reactive plumes at different radiation magnitudes are in- vestigated. Reactive plumes display periodic large vortical structures naturally in the flow field, due to the heat release and gravitational effects. As the radiation fraction is increased, the temperature of the flow field, the vorticity of the plume and the interactions of its 3D vortices at the downstream of the flow filed will all be significantly affected. It is also shown that radiation does not destroy the symmetry of the flow filed, and all the vortical structures are symmetrical as to the geometric center.