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

本项目旨在为分层充氢燃烧在火花点火发动机上的实际应用做基础性研究。由于氢气射流被环境气体快速稀释，出现了点火不可靠、燃烧不稳定、燃烧效率下降等问题，本研究采用等离子射流点火系统来实现燃料混合物的可靠点火和高效燃烧。从点火器的机械结构、燃烧空间的形状和提供的能量等方面对点火系统进行了分析。结果表明：1)由于喷射速度、喷射方向和喷射能量易于调整，优化该类型点火系统的自由度较高；2)由于初始火焰区域的快速形成，可以正确地调整主燃烧时刻。其次，研究了氢气喷射燃烧特性与点火时刻和点火位置的关系，以及等离子喷射点火在流动燃烧系统中的应用。结果表明，着火时刻和着火位置强烈依赖于喷嘴直径的大小和喷射持续时间。并对等离子-喷射点火系统在燃油喷射燃烧和旋转可燃混合物中的应用进行了进一步的研究。

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.