一种新的小缸径柴油机单孔直喷燃烧系统的研究

A Study of New Single Spray Direct Injection Combustion System for a Small Diesel Engine

小缸径柴油机燃烧系统直喷化已经成为发展趋势，但仍面临实现柔和运行及降低有害排放产物的难题。燃烧室周边混合式燃烧系统具有工作柔和、变速适应性好等优点，但由于形成较多的壁面面膜，而使燃烧速率低，ＨＣ和微粒排放品质差。为此，本文研究了旋转流场中轴针喷嘴油束扩展与混合的特性，提出了利用油束控生效应加这混合，改善燃烧过区的概念。在Ｓ１９５涡流室柴油机基础上设计了一种新的单孔直喷式燃烧系统。研究结果表明，该系统具有节油，工作柔和和低排放等优点，可以成为实用的小缸径直喷式燃烧系统。

In order to understand the fuel spray characteristics injected from various types of pintle nozzle located at periphery of combustion bowl in a small diesel engine, the effects of nozzle location, injection direction and air swirl on spray mixing and fuel wall wetting are investigated in a constant volume bomb by shadowgraphy. By adjusting the factors mentioned above and making strongerimpingement of fuel spray on chamber wall, faster spray dispersion and slighter wall wetting are obtained. Based on bomb observation, a new single spray direct injection combustion system for a small diesel engine is developed, which has the advantage in lower emissions and higher thermalefficiency