点火器冷却气流对点火过程影响的实验研究

Experimental Study on Effects of Cooling Airflow of Igniter on Ignition Process

关键词:  多通道等离子体点火器  冷却气流  基础燃烧室  点火过程  点火边界

Key words:  Multi-channel plasma igniter  Cooling airflow  Basic combustion chamber  Ignition process  Ignition boundary

摘要:

为提高多通道等离子体点火器的工作可靠性和使用寿命，解决放电引起的瞬时高温和工作环境长时间高温引发的点火器端部烧蚀问题，本文基于嵌入式多通道等离子体点火器和强制对流换热的冷却方式，设计研制了冷却型多通道等离子体点火器，并建立了单头部旋流喷雾基础燃烧室实验系统，开展了冷却型多通道等离子体点火器点火特性实验研究。利用CH*自发光信号诊断系统结合数值图像处理方法分析了放电通道数、冷却气流流量和来流流量对点火过程的影响，并比较了不同条件下的贫油点火边界。结果表明：冷却气流增大了贫油点火极限当量比和点火延迟时间。在400SLM来流、50SLM冷却气流条件下，多通道等离子体点火器的点火极限当量比为0.304，点火延迟时间为37.4ms，均大于无冷却气流工况。相较于单通道点火器，多通道等离子体点火器能显著拓宽贫油点火边界，且受冷却气流影响较小。在400SLM来流且无冷却气流条件下，多通道等离子体点火器可以拓展点火边界3.2%，而在50SLM冷却气流下拓宽效果达到3.7%。

Abstract:

In order to improve the operational reliability and service life of the multi-channel plasma igniter， and solve the problem of ablation failure of igniter end face caused by the instantaneous high temperature triggered by the large discharge energy and the long-term high temperature of the working environment， a cooled multi-channel plasma igniter is designed and developed based on the embedded multi-channel plasma ignition gun and forced convection heat transfer in this paper. A single-head swirl spray basic combustion chamber experimental system is established， and an experimental study on the ignition characteristics of the cooled multi-channel plasma igniter was carried out. Using the CH* self-luminous signal diagnosis system combined with the numerical image processing method， the effects of the number of discharge channels， cooling airflow and incoming flow on the ignition process were analyzed， and the lean ignition boundary under different conditions was compared. The results show that the cooling airflow increases the lean ignition limit equivalence ratio and ignition delay time. Under the condition of 400SLM incoming flow and 50SLM cooling airflow， the ignition limit equivalence ratio of the multi-channel plasma igniter is 0.304， and the ignition delay time is 37.4ms， which are both larger than those without cooling airflow. Compared with the single-channel igniter， the multi-channel plasma igniter can significantly broaden the lean ignition boundary and is less affected by the cooling airflow. Under the condition of 400SLM incoming flow and no cooling airflow， the multi-channel plasma igniter can expand the ignition boundary by 3.2%， while the broadening effect reaches 3.7% with 50SLM cooling airflow.