星形线电除尘器内EHD流动与粒子行为数值模拟

为了研究星形线电除尘器内电流体动力学（EHD）流动与荷电粒子运动行为及两者间相互作用，构建了线板式电除尘器（ESP）内关于EHD和带电粒子运动学的耦合数值模型.该模型采用有限体积法离散求解电场方程和空间电荷方程，在拉格朗日法下建立带电粒子运动方程，并与FLUENT湍流模型进行耦合.利用这一模型，对3种电场风速下星形线电除尘器内流动形态与粒子运动行为进行了细致模拟，并分析了二次流动对气流、粒子浓度分布的影响.结果表明，星形线电除尘通道内二次流动对流动形态和粒子浓度分布存在显著作用.随电场风速的降低，这一作用将越明显.EHD流动对细小荷电粒子运动的影响更为显著.二次流动产生涡旋并作用于主流来影响粒子运动行为.收尘板面的涡旋挤压粒子流远离壁面向流动中心运动，放电极下游的涡旋则促进粒子流向收尘板壁面靠近.此外，由于捕集通道中强二次流的存在，Deutsch计算式对除尘效率、特别是对于亚微米粒子捕集效率的计算并不准确.

Numerical analysis of EHD flow and particle behavior in electrostatic precipitators with Star-shaped electrode

Electrohydrodynamic (EHD) flow, charged particle behaviours and the interaction between the two phases were investigated in a wire-duct electrostatic precipitator (ESP) with Star-shaped electrode by employing a coupling numerical model of the EHD flow and charged particle dynamics. The model used the finite volume method to solve the electric field equation and the space charge equation, which couple with the FLUENT turbulence model, including the charged particle motion equation by the Lagrangian method, and the flow patterns and particle behaviours in the star-shaped ESP at three inlet velocities were simulated in detail. The secondary flow in the Star-shaped ESP channel has a significant effect on the flow pattern and particle concentration distribution. The influence of secondary flow on the flow pattern is more obvious as the inlet velocity decreases. The effect of secondary flow on particle behaviour is more evident for fine particles. The vortexes produced by secondary flow affect the particle behaviour by affecting the mainstream flow. The vortexes near the collecting wall squeeze the particle flow away from the wall, while the vortexes in the downstream of the discharge electrode promote the particle flow toward the collecting wall. The collection efficiency, especially the efficiencies of submicron sized particles, can not be estimated correctly by the Deutsch formula as the strong secondary flow exists in the ESP channel.