Characterization of gliding arc plasma ignition in aeroengine swirl combustion chamber

Gliding arc plasma-enhanced combustion is a relatively new combustion technology. This paper describes a gliding arc plasma combustion dome that improves the ignition characteristics of aeroengines. The ignition characteristics are studied using an experimental platform consisting of a single-combustion-dome swirl combustion chamber. A flame spontaneous radiation imaging technique is adopted to collect the C2* groups formed during the ignition process. We focus on the ignition mode, flame kernel propagation mechanism, ignition delay time, and ignition boundary of the gliding arc ignition process. The gliding arc ignition process has five stages with different characteristics: flame kernel stabilization, flame kernel expansion, intense combustion, combustion decay, and stable combustion. During the flame kernel propagation stage, the main flame kernel in the combustion dome splits into flame kernel 1, located in the recirculation zone of the upper wall, and flame kernel 2, located in the recirculation zone of the lower wall under the action of airflow. The main flame kernel reflects the direct action of the gliding arc. Unconsumed energy and active particles included in the main flame kernel are added to flame kernels 1 and 2 through sporadic splitting of the main kernel. This promotes the expansion rate of the fire nucleus in the combustion chamber. Compared with electric spark ignition, gliding arc plasma-enhanced combustion significantly widens the ignition boundary and shortens the ignition delay time of the combustion chamber. The ignition delay time can be shortened by up to 81.53% under an inlet flow rate of 55 m/s and a residual gas coefficient of 3; the ignition boundary can be widened by a maximum of 115.9% under an inlet flow rate of 5 m/s.