4190Z_LC型柴油机进气—压缩—燃烧过程的数值分析

发布时间：2018-02-14 03:17

本文关键词： 船舶中速柴油机工作过程数值仿真排放喷射参数　出处：《集美大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着能源危机的爆发和环境污染的日益严峻，人们对船用柴油机的经济性和排放性要求日益严格。本文研究的对象为4190ZLC型船舶中速柴油机，该机排放不满足IMO Tier II的排放标准要求。基于上述原因，学校决定对柴油机的供油系统进行改造，改善其经济性和排放性。利用AVL FIRE软件对4190ZLC柴油机的进气压缩过程进行了多维瞬态数值模拟，研究了气门运动对气道及气缸内流场分布的影响，分析流场的结构，得到不同时刻进气道和缸内的流场，研究发现：随着进气门的开启，缸内瞬时进气流量迅速增加，缸内气体的速度分布均匀性比较差；气门升程由大到小变化时，缸内压力场和速度场逐渐趋于均匀。在小气门升程时，由于气门盘的节流作用，导致进气喉口位置流速迅速变化，由于螺旋进气道的涡流作用，导致螺旋进气道下方涡团比切向进气道更靠近气门座位置；随着活塞的运动，缸内压力逐渐增大，湍动能由喉口位置向缸内逐渐扩散，最后湍动能以及温度在缸内均匀的分布。利用AVL FIRE软件中的ESE-Diesel模块建立4190ZLC柴油机的燃烧模型，仿真发现：喷孔锥角对柴油机的排放有显著影响，直接影响油束与空气的混合。采用140°的喷孔锥角时，可以得到最少的NOx排放，但碳烟排放较高；其它条件不变的情况下，减小喷孔直径可以使喷雾细化，使燃油与空气均匀的混合。0.26mm喷孔直径的碳烟排放恶化，0.28mm喷孔直径的NOx生成量最高；喷油提前角增大，导致NOx的排放恶化，但降低了碳烟颗粒的排放。
[Abstract]:With the outbreak of energy crisis and the increasingly serious environmental pollution, the requirements of economy and emission of marine diesel engines are becoming increasingly strict. The object of this paper is 4190ZLC medium speed diesel engine. The emission of the diesel engine does not meet the requirements of the IMO Tier II emission standard. For the above reasons, the school decided to improve the fuel supply system of the diesel engine to improve its economy and emissions. The multi-dimensional transient numerical simulation of intake compression process of 4190ZLC diesel engine was carried out by using AVL FIRE software. The effect of valve movement on the distribution of flow field in the air port and cylinder was studied. The structure of the flow field was analyzed and the flow field in the inlet port and cylinder at different times was obtained. It is found that with the opening of the inlet valve, the instantaneous intake flow in the cylinder increases rapidly, the velocity distribution of the gas in the cylinder is relatively poor, and when the valve lift varies from large to small, The pressure field and velocity field in the cylinder tend to be uniform gradually. In the small valve lift, the throttle action of the valve disk results in the rapid change of the inlet throttle velocity and the swirl effect of the spiral inlet. As a result, the vortex cluster below the spiral inlet is closer to the valve seat than the tangential inlet, and with the movement of the piston, the pressure in the cylinder increases gradually, the turbulent kinetic energy gradually diffuses from the throat position to the cylinder, and the final turbulent kinetic energy and temperature are uniformly distributed in the cylinder. The combustion model of 4190ZLC diesel engine is established by using the ESE-Diesel module of AVL FIRE. The simulation results show that the cone angle of the injection hole has a significant effect on the emission of the diesel engine, which directly affects the mixing of fuel beam and air. When the cone angle of the injection hole is 140 掳, the combustion model of the diesel engine is established. The minimum NOx emission can be obtained, but the soot emission is higher. If other conditions are not changed, the spray can be refined by reducing the diameter of the nozzle. The soot emission of 0.26mm injection hole diameter of the fuel and air mixture is aggravated. The NOx emission of 0.28mm injection hole diameter is the highest, and the fuel injection advance angle increases, which results in the deterioration of NOx emission, but decreases the soot particle emission.
【学位授予单位】：集美大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U664.121

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