湍流通道内微粒受力沉降特性模拟

利用建立的微粒受力模型和微粒随机轨道模型,对湍流通道中不同条件下微粒的受力进行了研究,对湍流通道中微粒的沉降特性以及影响因素进行了分析。研究结果表明,湍流通道中,柴油机微粒所受的曳力、布朗力、Saffman升力、热泳力以及重力和浮力等与微粒粒径、微粒距壁面的距离等因素密切相关;在不同条件下,微粒所受的主要作用力以及微粒沉降的主要驱动力不同;微粒受力、气流入口速度和温度以及通道尺度等因素都会对湍流通道中微粒的沉降产生影响。

Forces and Deposition Characteristics of Particles in Turbulent Flow Channel

The movement and deposition of the diesel particles have important effect on the particle sampling measurement, the operation of the exhaust gas recirculation system and the trapping of the particles. The forces imposed on the emission particles of diesel engine and the deposition characteristics of the emission particles of diesel engine in the turbulent flow channel were investigated under different conditions by using the force modes and the particle random trajectory mode established. The results showed that the Stokes drag force, Brownian force, Saffman lift force, thermophoresis force, gravitation force, and buoyancy force imposed on the emission particles had strong relations with the dimension of the particles and the distance of the particles far from the wall. The main driving forces for the depositing of the emission particles were different under different conditions. The forces, the flow inlet velocity and temperature and the channel dimensions affected the deposition of the emission particles in the turbulent flow channel.