Experimental investigation of ignition by multichannel gliding arcs in a swirl combustor

Abstract

In the extreme condition of high altitude, low temperature, low pressure and high speed, the aircraft engine have a strong tendency to extinct and difficult to start secondary ignition, which makes the re-ignition of the aircraft engine face great challenges. In addition, the ability of single-channel gliding arc (1-GA) assisting the ignition under extreme conditions is weak. In this paper, to solve this problem, a multichannel gliding arcs （MGA） is proposed by using the principle of multichannel discharge. Experiments on the electrical characteristics and ignition performance of MGA were conducted under atmospheric pressure in a swirl model combustor. The electrical characteristics of MGA were investigated under different air velocities. The ignition process of MGA was recorded by using the high-speed camera with CH* filter. Results show that the three-channel gliding arcs (3-GA) and five-channel gliding arcs (5-GA) generated more averaged power than the 1-GA under a constant air velocity. For example, the 3-GA and 5-GA generated 112.8% and 187.3% more averaged power than that of the 1-GA at 74.6m/s, respectively. The arc shapes of gliding arcs with different channel numbers were different and the duration time of "breakdown-stretching-extinguishing" of MGA shortened. Furthermore, compared with the 1-GA, the percentage of the lean ignition limit widening of the 3-GA and 5-GA can reach 13.5% and 20.9% respectively. The frequency of the re-breakdown in discharge process with different gliding arc channel numbers is different, which can continuously inject energy into the combustor and generated "flame combination" phenomenon producing a larger flame area. The ignition process of MGA can be divided into three stages: sliding stage, flame combination stage and flame stabilization stage.