MEAN VELOCITY AND TURBULENT INTENSITY PROFILES IN A LARGE SCALE LABORATORY PRECIPITATOR.
Despite the longstanding use of electrostatic precipitators, questions remain concerning the aerodynamic effects of corona discharge. While the electric body force on the gas produces a corona wind, corona induced secondary flow and turbulence are not understood, particularly as they occur in full scale precipitators. Limited experiments in small model precipitators confirm theoretical arguments that negative corona discharge creates turbulence; however these results may not be applicable to large commercial units. This paper presents an experimental investigation of the turbulent flow field in a large scale wireplate laboratory precipitator. The measurements include mean velocity and turbulence intensity profiles at gas speeds and corona current levels spanning the range of commercial practice. No evidence of an organized secondary flow was found, but the results indicate that corona discharge causes substantial increases in turbulence intensity even at relatively low current levels. This effect is less pronounced as the gas velocity increases from 0. 5 to 2. 0 m/sec. The rate of increase of turbulence intensity with current decreases dramatically at a current density of 0. 3 mA/m**2 which corresponds to the minimum discharge tuft spacing.