The reignition of aero-engine combustors at high altitudes poses significant challenges due to the low-temperature and low-pressure environment. A novel Long Pulse-Width Plasma Ignition (LPWPI) system has been developed to enhance ignition performance. The LPWPI system can effectively prolong the discharge duration time, improve ignition efficacy, and increase the plasma penetration depth. Experimental comparisons with the traditional Spark Ignition (SI) system demonstrate that the LPWPI increased discharge duration to 2.03 ms, which is 45 times longer than that of the SI system, while also doubling the spark penetration depth to 24.1 mm. The LPWPI system achieved a discharge efficiency of 61.1%, significantly surpassing the SI system’s efficiency of 23.3%. These advancements facilitated an extension of the lean ignition boundary by approximately 22.7% to 39.3%. High-speed camera recordings reveal that the spark duration of the LPWPI system was extended to 2.1 ms, compared to 0.6 ms in the SI system. Ignition progress with LPWPI shows a sustained spark kernel without the flame residence stage observed in the SI system. The impressive performance of the LPWPI system suggests that it is a promising alternative for aero-engine ignition systems.

Relight of jet engines at high altitude is difficult due to the relatively low pressure and temperature of inlet air. The penetration of initial flame kernel affects the ignition probability in the turbine engine combustor greatly. In order to achieve successful ignition at high altitude, a deeper penetration of initial flame kernel should be generated. In this study, a Gliding Arc Plasma Jet Igniter (GAPJI) is designed to induce initial flame kernel with deeper penetration to achieve successful ignition at high altitude. The ignition performance of the GAPJI was demonstrated in a model combustor. It was found that GAPJI can generate plasma with deeper penetration up to 30.5 mm than spark igniter with 22.1 mm. The discharge power of GAPJI was positively correlated with flow rate of the carrier gas, approaching 200 W in average. Ignition experiments show that GAPJI has the advantage of extending the lean ignition limit. With GAPJI, the lean ignition limit of the combustor is 0.02 at 0 km, which is 55.6% less than that with spark igniter (0.045). The evolution of flame morphology was observed to explore the development of the flame kernel. It is shown that the advantage of a high penetration and continuous releasing energy can accelerate the ignition process and enhance combustion.