直流滑动弧等离子体点火器特性的实验研究

Experimental Study on Characteristics of DC Gliding Arc Plasma Igniter

关键词:  直流滑动弧等离子体点火器  电弧长度  点火过程  点火延迟时间

Key words:  DC gliding arc plasma igniter  Arc length  Ignition process  Ignition delay time

摘要:

为了探究直流滑动弧放电应用于航空发动机燃烧室内点火的性能特点，本文设计了直流滑动弧等离子体点火器，在模型燃烧室内进行了煤油/空气混合气的点火实验，利用高速相机记录了滑动弧等离子体点火器的电弧产生和滑动过程以及燃烧室内煤油/空气混合气的点火和火焰发展过程，研究了不同空气工作介质流量、驱动电源输出电流、点火器电极夹角和点火器安装位置等因素对滑动弧等离子体点火器点火特性的影响。结果表明：滑动弧在运动过程中会产生不规则的跳动，并且存在着电弧分流的现象，导致电弧长度发生变化；在湍流的作用下，初始火核会演变为分裂的、大面积的湍流火焰，着火面积不断增大，最终在t=21ms时形成稳定燃烧；随着空气工作介质流量增大、驱动电源输出电流减小以及点火器的安装位置远离燃油雾化喷嘴，滑动弧等离子体点火器的电弧长度减小，点火延迟时间逐渐增长，例如α=8时，I=30A下电弧长度为47.1mm，相比I=20A增长了75.1%，点火延迟时间为21ms，相比I=20A缩短了40%；而随着点火器电极夹角的增大，电弧长度先增大后减小，点火延迟时间则先减小后增长，在电极夹角θ=45°时，电弧长度最长，点火延迟时间最短，分别为30.5mm和12ms。

Abstract:

In order to explore the performance characteristics of DC gliding arc discharge applied to ignition in the combustion chamber of an aeroengine, a DC gliding arc plasma igniter was designed in this paper and kerosene-air mixture ignition experiments were carried out in the model combustor. The arc generation and sliding process of the gliding arc plasma igniter and the development and propagation process of kerosene-air mixture ignition and flame in the combustor were recorded with a high speed camera. The effects of different air working medium flow rate, driving power output current, igniter electrode angle and igniter installation position on ignition characteristics of the gliding arc plasma igniter were studied. The results show that the gliding arc will produce irregular jump in the movement process, and there is a phenomenon of arc shunting, which leads to the change of arc length. Under the action of turbulence, the initial flame kernel will develop into a split, large area turbulent flame. The ignition area keeps increasing, and finally stable combustion is formed when t=21ms. The arc length of gliding arc plasma igniter decreases and the ignition delay time gradually increases with the increase of air working medium flow rate, the decrease of output current of driving power supply and the installation position of igniter away from fuel atomization nozzle. For example, when α=8, the arc length at I=30A is 47.1mm, which is 75.1% higher than that at I=20A, and the ignition delay time is 21mm, which is 40% shorter than that at I=20A. And with the increase of the igniter electrode angle, the arc length increases and then decreases, and the ignition delay time decreases and then increases. When the electrode angle θ=45°, the arc length is the longest and the ignition delay time is the shortest, which are 30.5mm and 12ms, respectively.