Improved Electric Plasma Torch for Ignition, Flameholding and Enhancement of Combustion in High Speed Flows

In the quest for successful combustion in high-speed flows with minimal shock losses, technology has been developed and implemented in Mach 2.4 cold flow at Virginia Tech. The flush-wall design avoids physical obstructions such as ramps, vanes, struts, etc. for liquid fuel injection, utilizing a unique injection/atomization technique which simultaneously mixes the fuel and air. Successful integration of the igniter, injector and atomizer has resulted in robust ignition of liquid hydrocarbon fuels in cold, low-pressure supersonic flow. The ignition has been evidenced by visible luminescence, UV-filtered photography, and temperature rise. The physical design of the injector/igniter utilizes wasted heat from the electric arc igniter to provide efficient regenerative heating of the fuel. Different injection schemes have been analyzed. Much lower igniter power levels than previously investigated have not diminished the ignition capabilities. It is noteworthy to realize the success of the design in the most adverse combustion environment: low temperature, low pressure, high-speed flow in a non-adiabatic duct without the presence of physical flameholders. The full magnitude of the significance of this technology will be realized when implemented in conditions more conducive to liquid hydrocarbons combustion. The design will be of interest to those seeking successful supersonic or high-speed ignition, particularly scramjet combustor designers and jet engine augmenter (afterburner) designers. However, the technology boasts additional experimental proof that may be useful to atomizer designers, high-speed injection specialists, and those seeking to minimize flameholder losses.

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