Asymmetric whirl combustion:: A new low NOx approach

A promising new approach for non-premixed low-NOx combustor design is presented in which fuel was injected off-axis or asymmetrically into a whirl flame. Experiments using this technique to react methane and air in an atmospheric laboratory-scale burner demonstrated low NO emissions levels coupled with modest CO emissions. NO emissions below 15 ppm were measured with associated CO below 25 ppm at 15% O-2. The combustor was shown to exhibit unusual stability characteristics even at overall equivalence ratios below phi = 0.1. Presented in this paper are the design of the novel whirl combustor, the results of an experimental characterization of the combustor emissions, and a numerical examination of the internal structure of the flame, which provides an explanation of this unusual behavior.