Deviation and atomization of a dielectric liquid sheet under electrohydrodynamic excitation

Abstract

A new electrohydrodynamic (EHD) actuator based on a dielectric barrier injection system has been developed in order to enhance fuel atomization in air blast atomizers. In industrial air blast atomizers, the fuel is injected at low pressure through an annular slit. The liquid sheet is then atomized by the shear forces exerted by the coflowing air stream. .High air velocities are needed in order to obtain a fine atomization. The objective was to electrically atomize the liquid sheet without the need to an external air flow like the one seen in air blast atomizers. In the proposed EHD actuator, the liquid sheet is atomized only with the help of electric forces and without any mechanical influence. Experiments have been carried out on 300 μm thin sheets of commercial Diesel oil with a very close flow rate to the ones used in turbo engines. The velocity varies between 0.6 m/s and 2 m/s. Images are recorded with a high speed camera. The liquid sheet could be fully atomized when the actuator is running. In this paper, the effect of the electric signal frequency on the mechanical behaviour of the excited sheet, mainly on the angle of deviation, is presented.