INTERACTION OF ELECTROSTATIC AND FLUID DYNAMIC FIELDS IN WIRE-PLATE PRECIPITATORS.

摘要

as flow through wire-plate electrostatic precipitators is influenced by a secondary flow of electrical origin known as electric wind. This phenomenon arises when significant momentum is transferred from corona-generated ions to the gas, capable of producing a turbulent, recirculating flow. Characterization of this complex flow field in a simple, three-wire precipitator was performed by flow visualization, electrostatic and fluid dynamic numerical modeling, and laser Doppler anemometry (LDA).;Velocity of seeded smoke was measured by two-component LDA. Coulomb effects were regionally eliminated by performing measurements along symmetry axes where the electric field and streamwise velocity component were mutually perpendicular. Coulomb drift velocities were also estimated from field charging theory to allow interpretation of measured transverse velocites. For a low inlet velocity (0.5 m/s), mean flow recirculation was evident and turbulence intensities as high as 50% were measured. Higher inlet velocities (1.0, 2.0 m/s) yielded no flow recirculation and lower turbulence levels that were polarity-dependent. Measured profiles of streamwise velocity showed that flow acceleration zones occurred upstream of each wire and also between wires near the collecting plate. The induced turbulence displayed significant inhomogeneity and anisotropy.;A combined finite-element, finite-difference electrostatic model was developed to yield accurate ion density and electric field distributions within wire-plate precipitators. These predictions were used to formulate an electric body force incorporated into a two-dimensional, turbulent fluid dynamic model based upon the k -;Smoke visualization by laser sheet illumination showed that the extent of electric wind effects is very sensitive to precipitator inlet flow. For inlet velocities less than