NUMERICAL INVESTIGATION OF ELECTRIC FIELD EFFECTS ON SPRAY JET FLAMES CONTAINING CHARGED DROPLETS

Transition to a zero-carbon transportation sector requires the development of fuel-flexible combustionsystems. The use of electrostatic fields offers the possibility to control both fuel mixingand flame characteristics. This study investigates the use of electrostatic fields to control aspray jet flame using charged droplets. The focus of this work is on the effects of an externalelectric field parallel to the jet direction on the spray penetration and the flame shape and location.This study is conducted using large-eddy simulations under the assumption that chargedspecies generated in the combustion process are negligible. Results show that with practicalelectrostatic fields and droplet charges achievable with state-of-the-art atomisers, it is possibleto significantly change the cold-flow spray penetration. Electric forces in the opposite directionto the spray jet lead to a reduction in the spray penetration, an effect that increases with strongerelectrostatic fields. This also leads to an increase in drag forces between the droplets and the airflow,resulting in a decrease in the penetration of the air jet. The lower penetration of dropletsunder electrostatic fields leads to a more compact flame in the corresponding reacting cases.Fuel vapour tends to be confined in a region much closer to the jet exit when the applied electricforce is in the opposite direction to the jet. Similar trends are also shown by the temperaturefield and mass fraction of the combustion products. This study suggests that electrostatic fieldscan provide an element of control over spray jet flames through the use of charged fuel droplets,and provides a basis for future investigations that could lead to the development of novel hybridthermal-electric combustion systems.