Effects of corona discharge on forced convection in tubes: pressure drop results

Electrohydrodynamic effects on forced convection in tubes can have significant implications for enhancement of heat exchanger performance in heat pumps and other devices. Of particular concern in such applications is the possibility of increased pressure drop associated with electrostatic discharge, which might substantially increase the pumping power required. The authors describe a series of experiments designed to determine the effects of corona discharge on pressure fields for air flow in cylindrical tubes. Experiments were performed with a single concentric electrode in the tube and with two nonconcentric electrodes. Measurements were performed at potentials from the onset of measurable current to near the sparkover point and at Reynolds numbers from 10/sup 3/ to 2*10/sup 4/. Friction factors were seen to increase as much as 250% over the values obtained in the absence of an applied electric field. The results presented suggest that the electrostatic effect on pressure drop is very sensitive to current density, Reynolds number, and electrode configuration.<>