Experimental study of steady quasi-cone-jet electrostatic sprays of biobutanol for engine applications

Butanol produced from agricultural sources is emerging as a potentially renewable biofuel for use in engine applications. In this work, butanol electrostatic sprays were established within a narrow region of low flow rates. Spray phenomenology was investigated through high-speed visualization for the low flow rate conditions in the vicinity of the lowest voltage for which electrosprays (e-sprays) could be sustained. Spray structure was studied through droplet size and velocity measurements for a combination of conditions, performed by using phase Doppler anemometry. Combined with high-speed spray visualization, these measurements revealed a stable e-spray operation with narrow droplet size and velocity distributions; i.e., spray behavior was close to monodisperse. A similarity analysis was performed to develop an empirical expression correlating appropriately dimensionless average diameter, flow rate, and applied voltage.