Spray Cpmbustlon Study for Super Low NOx Emission

柴油机燃烧过程受燃料-空气混合过程的影响很大，控制燃烧室内的燃料-空气混合过程是降低废气排放最有效的措施之一。特别是控制混合气的时空分布被认为是未来柴油机的关键技术。为此，通过计算机模拟、定容燃烧室和配备多喷油器的试验发动机，研究了燃料-空气混合气的时空分布对柴油机燃烧和排放过程的影响。主要研究结果如下：1.利用唯象喷雾燃烧模型对燃油喷雾的时空分布对尾气排放的影响进行了计算研究。通过计算，找到了同时降低N-…的有效措施更多的公牛和烟雾排放。利用电控共轨喷射系统和高压高温爆发器，研究了分流喷射柴油机喷雾的行为和特性。其中一种喷雾从多孔喷嘴注入安装在高压高温炸弹中的二维模型燃烧室。用纹影照相法、聚焦阴影照相法和高速摄像机对喷雾进行了观察。阐明了分流喷雾的空燃形成和喷雾特性。研究了不同喷雾空间布置方式下直喷式柴油机的燃烧和排放特性。在发动机中加长气缸套和安装平顶活塞，以获得各自较大的煎饼式燃烧室。这种改装使发动机有可能在燃烧室中获得六到十个喷嘴的径向布置。阐明了燃油喷雾的空间分布对柴油机燃烧和排放的影响，为开发低NOx和烟度排放的发动机提供了指导。较少

Diesel combuston processes are significantly affected by the fuel-air mixing process, that is one of the most effective measure for reducing exhaust gas emissions is controling the fuel-air mixing process in the combustion chamber. Especially, controling spatial and temporal distributions of fuel-air mixture is considered to be the key technology for future diesel engines. Therefore, the effects of the spatial and temporal distributions of the fuel-air mixture on diesel combustion and exhaust processes were examined by using a computer simulaiton, a constant volume combustion chamber and an experimental engine equipped with multi-injectors. The results of the current study are summarized as follows :1. A calculative investigation was performed in order to examine the effects of temporal and spatial arrangement of fuel sprays on exhaust emission using a phenomenological spray combustion model. As a result of the calculations, effective measures were found for simultaneous reduction of N … More Ox and smoke emissions.2. Behaviors and characteristics of the diesel spray with split-injection were studied by using an electrically controlled common rail injection system and a high pressure and temperature bomb. One of the sprays were injected from a multi-hole nozzle into a 2-dimensional model combustion chamber installed in the high pressure and high temperature bomb. The spray was observed by schlieren photography, focused-shadow photography and a high speed video camera. Air-fuel formation and characteristics of the spray with split-injectionwas clarified.3. Characteristics of combustion and exhaust emission of D.I.Diesel Engine were investigated under various spatial arrangement of fuel sprays. A cylinder liner was elongated and a flat-top piston was installed in the engine in order to obtain a respectively large pancake-type combustion chamber. Such modification the engine made it possible to obtain radial arrangement of six to ten spravs in the combustion chamber. Effects of spatial distribution of fuel sprays on diesel combustion and exhaust emissions were clarified.All these things made it clear that the guides for developing low NOx and smoke emission engines were obtained. Less