Direct Arc Injection Method (DAIM), which is our original and takes the form of discharging dc arcs directly into the combustion chamber, has been investigated on its ignition capability in supersonic airflows. In this study, the ignition performance of the DAIM was evaluated by comparing experimentally with the plasma torch method, one of the most common forced ignition methods for supersonic combustion, for both the upstream and downstream fuel injection cases. The results indicated that DAIM was superior to the plasma torch method on ignition: in downstream fuel injection case, DAIM ignited methane with about half electrical energy input as much as plasma torch needed possibly because DAIM maintained the heat and radicals active longer near downstream side of the ignitor.
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