Abstract
A novel coaxial jet nozzle equipped with a row of miniature electromagnetic flap actuators was applied to active control of a methane-air diffusion flame. The flame and associated flow structures were studied through flow visualization, while the combustion gas composition at a postflame location was investigated by an FT-IR exhaust gas analyzer. The flap motion synchronized with a square-wave signal at the preferred mode frequency was found to be effective in stabilizing the lifted flame, because it provided a well-mixed fuel-air mixture at its flame base, achieving low NOx emission. On the other hand, a sawtooth-wave signal control stabilized the lifted flame dramatically, and led to low UHC emission with successive supply of large scale vortices at its flame base.
