Comparison of ignition characteristics between annular and multi-sector combustor

Abstract

In order to establish the coupling connection of the ignition characteristics between the multi-injector burner and the annular combustor. The ignition process is investigated experimentally with/without the end-wall under the same multi-injector combustor rig. The spontaneous flame emission is recorded by an intensified high-speed camera on the side and top view. The image edge detection technology is used to obtain the leading point (LP) trajectories of the flame and the subsequent quantitative information (ignition delay time, light-round speed et al.). The results illustrate that a successful ignition of the multi-sector combustor can be decomposed into three flame propagation phases (I, II, III). The flame propagation speed can be improved by increasing air velocity and equivalent ratio. This effect will be obvious when it is close to the light-round limits. The light-round limit of the annular combustor is slightly lower than that of the multi-sector combustor. The flame fronts propagate symmetrically on both sides and tend to move along the radial centerline in the multi-sector confinement. While they propagate asymmetrically on both sides in the annulus confinement and are close to the inner or outer wall. The flame propagates slower in the multi-sector combustor than that in the annular combustor due to the restrictive effect of the end-wall on the expansion of the hot gas. This gap becomes greater when the flame approaches the end-wall. Higher bulk velocity conditions will also lead to a greater gap in light-round speed between annular and multi-sector combustors. This paper measures and summarizes the differences in ignition characteristics between the annular and multi-sector combustors. It is critical for the transition of the ignition prediction from the multi-injectors combustor to the annular combustor.