Showing papers by "Walter F. O'Brien published in 2006"

Integrated Aeroramp-Injector/Plasma-Torch Igniter for Methane and Ethylene Fueled Scramjets

Abstract: An integrated aeroramp-injector/plasma-torch igniter configuration has been experimentally tested in conditions simulating scramjet flight at a Mach number of 4. Ethylene (C2H4) and methane (CH4) were used as fuels with air as the torch feedstock gas. A range of equivalence ratios (φ) were tested to determine operability limits. Successful combustion was determined by observing wall-static pressure rise in the facility, as well as wall temperature increases. A long isolator in the facility allowed for dual-mode operation, and both subsonic and supersonic combustion modes with good efficiency were observed with ethylene fuel. Poor results were obtained with methane in the same configuration as was successful with ethylene. The GASP numerical solver was used to evaluate the suitability of the plasma torch location with respect to the aeroramp injector center. An analysis of the mixing of each fuel through the aeroramp indicated that the selected torch location for methane was not ideal, as opposed to the ethylene case, for which it was predicted as good. The predictions were in accord with the experimental results. This lends confidence to the idea that CFD can be used to help select a better configuration for methane.

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

Abstract: 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.