【作者】 王先勇；

【导师】 周校平； 缪雪龙；

【作者基本信息】 上海交通大学 ， 动力工程， 2007， 硕士

【摘要】 如何降低内燃机有害排放物,是大家共同关心重视的课题。特别是柴油机如何同时降低NOx、PM排放是一个非常重要的课题,因此内燃机工作者正在探索既经济又有效的新途径来降低排放。本课题通过研究一种理论上在柴油机能够实现预混合燃烧并且能避免目前预混合燃烧系统HC、CO等排放高的缺陷的一种新型油嘴——超多喷孔油嘴,与传统油嘴对比分别进行了喷油特性和喷雾特性的测试与分析,最后在柴油机上进行了预混合燃烧的试验对比分析。论文首先试制了3种参数的超多喷孔油嘴,为提高流通能力还对喷孔进行了液力挤压研磨,并设计了与之配套的直口燃烧室。然后在EFS喷油泵试验台上详细测试了超多喷孔油嘴与传统油嘴的喷油规律并进行分析研究,了解其喷油速率、喷油持续期、喷油结束时针阀关闭速度的区别。然后再借助高速摄影仪进行了两种类型机嘴喷雾特性的高速摄影研究,了解其油束贯穿距离、贯穿速度和喷雾外廓角方面的特性。在处理高速摄影的图像时,基于MATLAB平台,开发了计算机图像自动数据提取分析软件。最后在柴油机上进行了两种油嘴在不同EGR率、不同喷射压力和喷射始点下的油耗和排放指标的测试分析。研究结果表明,本超多喷孔油嘴在一定油量以上相比传统油嘴能明显提高喷油速率,缩小喷油持续期,加快针阀落座速度,能减小油束贯穿距离,改善雾化质量。发动机试验也表明,比较有利于形成预混合燃烧,NOX和PM都有明显的下降,并克服了现有预混合燃烧HC、CO排放增加的缺陷,比油耗也基本不变。试验证明通过超多喷孔油嘴来实施柴油机的预混合燃烧也是一种可行的方案。更多还原

【Abstract】 How to reduce the harmful exhaust emissions from the internal-combustion engines (ICE) has become a common concern issue. Especially for diesel engines, how to reduce simultaneously the PM and NOx emissions is a key issue. So the engineers are searching for an efficient and economical way to reduce the emissions from ICE. This paper is mainly engaged in the development of a new type of fuel injection nozzle, namely the ultra-multi-hole injection nozzle, which can be applied to real diesel engines to realize the premixed combustion in theory and avoid the increase of HC and CO emissions using the existing premixed combustion methods. Experiments have been conducted in the fuel injection spray characteristics. And the results between conventional injection nozzles and super-number-hole injection nozzles in the tested engine are comparatively analyzed in the end.According to the principle of ultra-multi-hole injection nozzle, three types of this injection nozzle with different parameters are manufactured. The injection holes are treated with hydro-grind to increase flow rate. The combustion chambers are designed to match the spray. The experiments of the fuel injection spray characteristics of both the conventional injection nozzles and the super-number-hole injection nozzles are done on the EFS Fuel Injection test bench. All the needed results about the injection rate、injection duration and the needle valve closing velocity are also obtained. The characteristics such as fuel penetration distance、velocity and spray angle of outside expand are measured using high speed photography and the image are treated with the software base on MATLAB. The experimental results of diesel engine between conventional and ultra-multi-hole injection nozzle are compared at different conditions, such as different EGR rates, different injection pressure and injection timing.Ultra-multi-hole injection nozzle provides better characteristics than traditional injection nozzle on injection rate, injection duration, valve closing velocity, spray penetration and atomization. The results showed NOx and PM emissions simultaneous reduced prominently, and meanwhile HC and CO emissions were effectively controlled using existing premixed combustion. All the results showed that ultra-multi-hole injection nozzle is one of the feasible methods to realize the premixed combustion in diesel engine.更多还原