Abstract
Finding a new ignition strategy for ignition enhancement in a lean-burn combustor has always been the biggest challenge for high-altitude, long-endurance unmanned aerial vehicles (UAVs). It is of great importance for the development of high-altitude, long-endurance aircraft to improve the secondary ignition ability of the aero-engine at high altitude where the ignition capability of the aero-engine igniter rapidly declines. An innovative ignition mode is therefore urgently needed. A novel plasma-assisted ignition method based on a multichannel discharge jet-enhanced spark (MDJS) was proposed in this study. Compared to the conventional spark igniter (SI), the arc discharge energy of the MDJS was increased by 13.6% at 0.12 bar and by 14.7% at 0.26 bar. Furthermore, the spark plasma penetration depth of the MDJS was increased by 49% and 103% at 0.12 bar and 0.26 bar, respectively. The CH* radicals showed that the MDJS obtained a larger initial spark kernel and reached a higher spark plasma penetration depth, which helped accelerate the burning velocity. Ignition tests in a model swirl combustor showed that the lean ignition limit was extended 24% from 0.034 to 0.026 at 25 m/s with 20 °C kerosene and 17% from 0.075 to 0.062 at 12 m/s with −30 °C kerosene maximally. The MDJS was a unique plasma-assisted ignition method, activated by the custom ignition power supply instead of a special power supply with an extra gas source. The objective of this study was to provide a novel multichannel discharge jet-enhanced spark ignition strategy which would help to increase the arc discharge energy, the spark plasma penetration depth and the activated area without changing the power supply system and to improve the safety and performance of aero-engines.
Highlights
It is crucially important for the safety and development of aero-engines to improve the secondary ignition ability because of the relatively low pressure, low temperature and high velocity of inlet air [1,2,3]
The highprobe voltage probe was connected to the point close to the so igniter approximately kV
The voltage was connected to the point close to the igniter that voltage is approximately 8 kV
Summary
It is crucially important for the safety and development of aero-engines to improve the secondary ignition ability because of the relatively low pressure, low temperature and high velocity of inlet air [1,2,3]. Once an aircraft has reached a flight height where the engine stops and the requirements for successful relight cannot be met, it is forced to move to a lower flight height to achieve secondary ignition. Improving the secondary ignition ability of the igniter plays a vital role in the safety and performance of aircraft. Low pressure and low temperature may cause many problems, for example, a poor fuel vaporization and a slow chemical reaction, a reduced appropriate ignition area, an increased minimum ignition energy, a reduced ignition energy, and a subdued spark penetration capability, which result in the lack of.
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