Effect of primary hole position and ignition position on the ignition performance of a reverse flow combustor

Abstract

The purpose of this paper is to analyze the influence of the primary hole position and ignition position on the flow field and ignition performance of the reverse flow combustor. Igniters of two schemes are located on the side wall, and the other two are in the outer liner. The lower primary hole with the axial distance value of 29.2 and 24.7 mm are employed for each type of scheme. These four schemes are experimentally studied by particle image velocimeter (PIV) and high-speed camera. The differences of ignition performance between the four schemes are analyzed from the flow field structure and ignition process. The results show that the propagation mode of flame kernel will change with the change of ignition position. When the flame kernel forms in the central region of the combustor, both upper and lower recirculation vortices are ignited simultaneously, resulting in a shorter ignition time. However, when the flame kernel is formed near the outer liner, the upper recirculation vortex ignites first, and then the lower recirculation vortex is ignited, resulting in a relatively longer ignition time. Ignition performance is mainly determined by the flow velocity near the flame kernel. There is a negative correlation between ignition performance and the local flow velocity. Increasing the transverse flow velocity near the flame kernel, the ignition performance will decrease. The overall ignition time is significantly influenced by the propagation path of the flame kernel. In a reverse flow combustor, changes in the position of the primary hole result in two typical flow fields, the ignition time mainly depends on the distance between the flame kernel and the recirculation vortices.