Browsing by Author "Billingsley, Matthew C."

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    Plasma Torch Atomizer-Igniter for Supersonic Combustion of Liquid Hydrocarbon Fuels
    Billingsley, Matthew C. (Virginia Tech, 2005-12-16)
    To realize supersonic combustion of hydrocarbons, an effective atomizer-igniter combination with the capabilities of fuel preheating, atomization, penetration, mixing, ignition and flameholding is desired. An original design concept incorporating these capabilities was built and tested at Virginia Tech, and was found to provide good penetration, effective atomization, and robust ignition and flameholding. Quiescent testing with kerosene and JP-7 provided initial performance data. The atomizer-injector design was then modified for insertion into a supersonic wind tunnel, and tested with kerosene in an unheated Mach 2.4 flow with typical freestream conditions of To = 280 K and Po = 360 kPa. Water injection was utilized in both cases for comparison and to analyze atomization behavior. In the quiescent environment, the regeneratively cooled plasma torch igniter was found to significantly increase electrode life while heating, atomizing, and igniting the liquid fuel. Jet breakup length was measured and characterized, and mean droplet size was estimated using an existing correlation. Several qualitative observations regarding quiescent combustion were made, including torch power effects and the process of flame formation. In the supersonic environment, the effect of fuel injection direction was analyzed. Best results were obtained when fuel was injected with a velocity component opposite to the direction of main tunnel flow. Repeatable ignition occurred in the supersonic boundary layer at the fuel stagnation location near the plasma torch plume. Direct, filtered, shadowgraph, and schlieren photographs, temperature measurements, and visible emission spectroscopy provided evidence of combustion and the details of the flame structure. The new atomizer-igniter design provided robust and reliable ignition and flameholding of liquid hydrocarbon fuels in an unheated supersonic flow at M=2.4, with no ramp, step, or other physical penetration into the flowpath.
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    Plasma torch for ignition, flameholding and enhancement of combustion in high speed flows
    (United States Patent and Trademark Office, 2009-08-11)
    Preheating of fuel and injection into a plasma torch plume fro adjacent the plasma torch plume provides for only ignition with reduced delay but improved fuel-air mixing and fuel atomization as well as combustion reaction enhancement. Heat exchange also reduced erosion of the anode of the plasma torch. Fuel mixing atomization, fuel mixture distribution enhancement and combustion reaction enhancement are improved by unsteady plasma torch energization, integral formation of the heat exchanger, fuel injection nozzle and plasma torch anode in a more compact, low-profile arrangement which is not intrusive on a highspeed air flow with which the invention is particularly effective and further enhanced by use of nitrogen as a feedstock material and inclusion of high pressure gases in the fuel to cause effervescence during injection.