Experimental investigation on gliding arc plasma ignition in double-head swirling combustor

Abstract The ignition and flame stabilization of an aeroengine have been the key problem of research under extreme conditions such as low temperature, low pressure, and high altitude. The gliding arc discharge is identified as having the potential to expand lean ignition limit and blow out limit. In this paper, the instantaneous power of the gliding arc and the CH⁎ chemiluminescence imaging of the ignition process are investigated in the double-head swirling combustor. The results show that the averaged power of the gliding arc is reduced in a low-pressure environment, and the three-channel gliding arc (3-GA) is more sensitive to the changes of inlet flow velocity. At the low-temperature environment range from T = 228 K to T = 288  K , the averaged power of the single-channel gliding arc (SGA) is only 211 W, while the averaged power of the 3-GA is 535 W, nearly 153% higher than that of the SGA. As the altitude increases, the averaged power of gliding arc decreases. As the ambient pressure in the combustion chamber decreases, the blow-out limit of the combustor is correspondingly broadened under the excitation of the gliding arc. The fuel-air ratio (FAR) is negatively correlated with the averaged power. Except at P = 70 - 90 kPa, the combustion chamber excited by the 3-GA exhibits a wider lean ignition limit. The FAR increases with the altitude increases. Compared with traditional spark igniter, the lean ignition limit of the SGA is broadened by about 67%. The lean ignition limit is broadened by about 20% on average by the 3-GA, especially by 31% at an altitude of 6 km. The lean blow-out limit is broadened by 18.2% on average, especially by 25% at ground state. The success of gliding arc ignition is related to whether the excited flame propagates into the main recirculation area to form a resident flame in the double-head swirling combustion chamber. The ignition delay time of the SGA is less than that of the 3-GA, which is related to the fact that the SGA is stretched further downstream of the combustion chamber under the action of inlet air flow, and the energy of a single channel in 3-GA is less than the centralized energy of the SGA.