Boundary Condition of DC Monopolar Ion Flow Field

摘要

Ion flow field is important in the study of performance of electrostatic precipitator used in electrical power stations For the removal of dust from furnace gas flow. Ion flow field results in the third- order nonlinear partial differential equation nabla ▽* (Δ Φ nabla Φ)=0. Because it is third-order, Dirichelt or Neumann boundary conditions on potential are not sufficient. An extra boundary condition, space charge density at the surface of electrode, is required. There is now a relatively large literature on the ion flow field. From earlier work to recent work, the extra condition, namely, the space charge density, is generally specified at the surface of coronating electrode. According to the current continuity equation, the space charge density can be specified at the surface of either coronating electrode or the plate electrode. This paper points out that there will be two shortcomings if the space charge density is specified at surface of the coronating electrode and suggests that the space charge density should be specified at surface of the plate electrode. According to the new method specifying space charge density at surface of the plate electrode first time, computation solutions solved by characteristics- hodograph method give more satisfaction than the way specified the space charge density at the coronating electrode.