Fabrication and Testing of Tapered Electro-spray Nozzles

Report No. ARL-TR-6226
Authors: Brendan M. Hanrahan and C. Mike Waits
Date/Pages: September 2012; 30 pages
Abstract: The U.S. Army is interested in compact fuel-to-electric power systems to provide portable power sources for Soldiers and unmanned aerial vehicles (UAVs). This work describes multiple methods aimed at creating microfabricated, tapered-tip, electro-spray (E-spray) nozzles for efficient fuel injection. It has been shown that E-spray scaling depends on a number of factors, including nozzle/emitter geometry. Use of the new tapered nozzle tip diameters of 18 μm compared to a previous minimum of 30 μm allowed for E-spray operation below 0.01 ml/h at 70 °C fuel pre-heat, which is a 25-fold decrease over the minimum of 0.25 ml/h possible with 90-μm-diameter, flat topped nozzles at 56 °C. A dense array of tapered nozzles could meet a minimum power requirement, while using very low flow rates per nozzle to obtain small combustor geometries.
Distribution: Approved for public release
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Last Update / Reviewed: September 1, 2012