【摘要】 为了揭示颗粒在湍流分离流动中的弥散机制,采用大涡模拟方法和颗粒轨道模型,对二维后台阶分离流动中颗粒弥散进行了数值模拟研究。研究给出了不同St数的颗粒在流场中的分布以及瞬时大涡与颗粒相互作用规律,表明大尺度涡对颗粒弥散的影响依赖于颗粒的尺寸等参数。不同St数下颗粒瞬时弥散机制不同,共有3种模式:随着颗粒St数的增大顺序表现为大涡作用模式;大涡与离心力作用模式;惯性力作用模式。进一步分析得到了颗粒进入回流区是大涡与颗粒的相互作用以及壁面的存在共同导致的结果。更多还原

【Abstract】 The particle dispersion mechanism in turbulent separated flow was studied numerically by analyzing the particle dispersion in the separated flow behind a two-dimensional backward facing step. The gas flow was simulated using a large eddy simulation with the solid particle motion traced by the particle track model. The simulations show the particle distribution variation for various different St numbers in the flow field and the regularity of the interaction between the large eddy structures and the particles. The results show that the effect of the large eddies on the particle motion depends on the particle parameters such as particle size. The particle dispersion mechanism differed for different St numbers. Three modes are identified, the large eddy structure transport mode for StO(1), a combined large eddy structure and centrifugal force transport mode for St~O(1), and an inertia force transport mode for StO(1). The particles enter the re-circulating region due to particle-vortex interactions and wall bonding in the separated flow.更多还原