Experiment and Analysis of Flow Field in a Wire-Duct Type Electrostatic Precipitator

1.电晕放电电场分析：提出了一种求解线管式电除尘器空间电荷场方程的新方法。用该方法计算了电晕电流密度、电晕电流密度和极板上电场分布的理论值，与实测值吻合较好。用该方法求出了放电与极板之间气体空间内的电势、电荷密度和电场分布。电除尘器内的流动分析：基于以外力为库仑力密度的N-S方程和连续性方程，数值分析了电晕放电对流场的影响。采用交替方向隐式方法计算随时间变化的涡量，用有限元方法计算涡量和流函数的泊松方程。结果表明，电流体动态数是特征离子风速与进口风速之比，得到了电流体动力场的特性。电除尘器内流场实验：采用Schiieren方法对电除尘器内的流场进行可视化拍摄。结果表明，电除尘器内的流场和集流板电极附近的旋涡对电除尘器内的流场有明显的影响。研究发现，电除尘器内流场的相似规律为：相同电流体动力学数时，流场形态基本相似。

1. Analysis of corona discharging electric field : A new method of solving the equations that describe the space charge field in a wire-duct type electrostatic precipitator is presented. The theoretical values of corona current-voltage characteristics, coronacurrent density and electric field distributions on the plate are calculated by the new method and are in good agreement with the measured values. This method is used to find the distributions of potential, charge density and electric field in the gas space between the discharge and plates.2. Analysis of flow in ESP : The effects of corona discharge on the flow field are numerically analyzed on the basis of Navier-Stokes equations with external force as Coulomb force density and the continuity equation. Time-dependent vorticity is calculated by alternating direction implicit method while Poisson equation for vorticity and stream function by finite element method. As a result, the characteristics of electrohydrodynamic flow field are clearly obtained as a function of electrohydrodynamic number which is defined as a ratio of characteristic ionic wind velocity and inlet flow velocity.3. Experiment of flow field in ESP : The flow field in ESP is visualized and photographed by Schilieren method. As a result, the effects of both on the flow field in ESP and of vortex near collecting plate electrode are clearly observed in the experiment. It is found that the similarity law concerning to flow field in ESP holds : the patterns of flow field are nearly similar for the same electrohydrodhnamic number.