Experimental Results of an Electrostatic Injector

Abstract : The objective of the current research is to assess the effects of electrostatic injector designs and charge energy on the spray break-up process of JP-8 fuel. Electrostatic injectors improve the liquid fuel spray atomization at low fuel pressures through the introduction of additional columbic forces on the spray particles. While charge injection introduces the columbic forces on the fuel before the nozzle exit, electrostatic injection applies the electric potential to the spray immediately after the fuel exits the nozzle. The application areas include carbureted and port fuel injections in small engines to improve fuel-air mixing. In this study, two different electrostatic injector designs were tested in an ambient chamber with four optical windows. The separate designs consist of basic slot nozzle geometries with varying nozzle dimensions as well as different electrode setups. Shadowgraphy and Mie scattering techniques were used to assess the spray characteristics such as spray patterns, onset of break-up, and atomization. Shadowgraphy with a micro zoom lens was used to measure droplet distributions and droplet velocities. The tests, which were conducted at the ARL Spray Combustion Research Laboratory in Aberdeen Proving Ground, MD, consist of a constant JP-8 spray and a single 7 ms electric potential pulse of up to 3 kV. The quantitative and qualitative analysis of the results is presented to characterize the behavior of electrostatic injector designs. Both of the electrostatic injectors analyzed in this study were able to produce break-up in the fuel spray at various Reynolds numbers and applied electrostatic charges.

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