A fundamental research on the combustion of a stratified hydrogen charge by plasma-jet ignition source

本课题旨在为火花点火发动机分层装药燃烧的实际应用进行基础研究。由于氢气射流被周围气体迅速稀释，产生了点火不可靠、燃烧不稳定、燃烧效率降低等问题。本文采用等离子体喷射点火系统，实现了混合气的可靠点火和高效燃烧。从点火器的机械结构、燃烧空间的形状和供能量等方面对点火系统进行了研究。结果表明；1)这种类型的点火系统的优化自由度很高，因为喷射速度、方向和能量供应都很容易调整；2)由于初始火焰区形成迅速，主燃烧时间可以正确调整。其次，研究了氢射流燃烧特性与点火时间和点火位置的关系，并对等离子体射流点火在流动燃烧系统中的应用进行了研究。结果表明，点火时间和地点在很大程度上取决于喷射直径的大小和喷射持续时间。进一步探讨了等离子体喷射点火系统在燃料喷射燃烧和旋转可燃混合物中的应用。

This project was planned to make a fundamental research for the practical use of a stratified hydrogen charge combustion in a spark ignition engine. Because of a rapid dilution of hydrogen jet by the ambient gas, many problems come about such as an unreliable ignition, an unstable combustion, a decrease in combustion efficiency, etc. In this research, a plasma-jet ignition system was applied for the reliable ignition and the efficient combustion of the fuel mixture. The ignition system was examined with a mechanical structure of igniter, a shape of combustion space, and a quantity of energy supplied. Results showed ; 1) a degree of freedom for the optimisation of this type of ignition system was high since the injection speed, the direction, and the energy supply to the jet were easy to adjust, 2) a main burning timing was correctly adjustable because of a rapid formation of initial flame zone.In the next place, the characteristics of the hyprogen jet combustion were investigated in relation with the timing and the position of ignition in the jet, and also investigated on the application of the plasma-jet ignition for the flowing combustion system. As a results, it was made clear that the timing and the place of ignition strongly depend on the size of a jet diameter and the injection duration. And further investigation has been made on the suitable application of the plasma-jet ignition system for the fuel jet combustion and for the swirling combustible mixtures.