Toward High Q, Evanescent Coupled Microwave Controlled Combustion

Recent progress in microwave enhanced combustion technology has focused on two main tasks: improving the coupling efficiency of the microwave/flame interaction and designing a system in which the flame can be enhanced outside of the strict confines of a resonant waveguide. The first task has met success with the use of pulsed microwave technology, and accurate laser diagnostics have been performed to measure temperature and OH number density of the pulsed microwave interaction with a CH4/air flame. The second task has been addressed with an evanescent waveguide configuration that effectively leaks microwave energy through an exposed waveguide surface into a region inhabited by a flame. The fabrication and initial experiments with this system have demonstrated the ability to generate an evanescent wave that can interact with loads external to the microwave cavity. The joint application of the efficient pulsed microwave/flame interaction with evanescent waveguide techniques supports the possibility that this technology may have practical applications to combustor design.