Atomization behaviour of a hybrid air-blast-electrostatic atomizer for spray combustion

Abstract

An analysis of the atomization region of a series of diesel sprays generated from a hybrid (air-blast & electrostatic) atomizer is presented. The atomizer has been specifically designed to operate on single or hybrid mode to enable the delivery of a charged and/or air-assisted spray for combustion applications. High speed microscopic backlit imaging is applied over a range of operating conditions. A noticeable influence of charge on the measured droplet and ligament size and their numbers is observed at all the tested aerodynamic Weber numbers (We = 2.4, 5.2, 8.2, 11.2). The experimental results reveal that an increase in spray specific charge can reduce both droplet and ligament sizes while a significant increase in droplet count is noted. The influence of charge is found to vary depending on the aerodynamic Weber number, with a more noticeable influence on the atomization behaviour for the lowest Weber number case (We = 2.4). When operating in a hybrid mode, a minimum spray specific charge (0.14C/m3) is required for the applied electric potential to influence the aerodynamically assisted spray.