Electrostatic Dispersion of Diesel Fuel Jets at High Back Pressure

Abstract

An experimental study of electrostatically atomized and dispersed fuel jets has been conducted in room temperature N2 gas for various back pressures to 41.8 atm. No. 2 diesel fuel was injected through an electrostatic spray triode designed for high-pressure operation. Charge density measurements were conducted at various combinations of injection velocities, electric potentials, and back pressures. The charge density of fuel drops increased up to 1.5 C/m3 with increasing electric potential until breakdown occurred. After breakdown the charge density was reduced by 40 to 60 percent and again increased but more slowly as electric potential increased. At higher flow rates, breakdown occurred at higher voltages. At higher back pressure, lower charge density was obtained and breakdown occurred at higher voltages. Visual observations showed that significant electrostatic dispersion was accomplished at high back pressures, and that the average drop size was about the same as the spray triode orifice diameter.