轻量化单缸直喷式柴油机喷油器与燃烧系统匹配研究

发布时间：2019-06-24 20:01

【摘要】：在工业革命之后,人类在近一百年的时间里大肆消耗非再生能源,造成能源短缺和环境恶化等问题。柴油机又是推动人类文明进步的一环,所以研发更具经济环保而又有强劲动力的柴油机有非常大的前景。对于直喷柴油机,缸内气体流动、混合气的形成对燃烧的好坏和污染物的排放起着至关重要的作用。虽然电控技术能根据柴油机的工况提供最佳的喷油量,喷油压力也不受内燃机转速的影响。但考虑到工作环境,造价以维修成本等因素。目前对非道路小型农用的柴油机还是通过改进缸内气流的运动,提高可燃混合气的质量来提高其动力经济性。由于GD190单缸柴油机的轻量化设计,使得气缸上的设计布局十分紧密,所以通过对设计指标的估算确定所需喷油器的基本尺寸,对气缸的设计会带来便利。本文研究首先估算了喷油器喷孔的大小,CFD软件AVL FireESE模块建立了喷油器与燃烧室的计算模型,然后,运用AVL Fire软件建立全模型,获得喷孔锥角、喷嘴深度和燃烧室偏置等参数对燃烧的影响。模拟结果表明：对于高速短行程单缸柴油机,在喷油压力、喷孔直径以及燃烧室相同的情况下,需要匹配有较大喷孔锥角的喷油器,且喷油器的安装深度需要较深。在喷孔锥角太小时,油束的切向力不能与从气缸环形流入燃烧室内的气流相匹配形成有利于燃油蒸汽雾化的涡旋。而喷油嘴安装深度较小时,容易使燃油蒸汽依附在气缸盖顶部,不利于燃烧。在油束夹角,以及喷油嘴安装深度不变时,使燃烧室整体偏移活塞中心5mn,喷油器还是安装在燃烧室正上方。仿真结果显示,在2600r/min,满负荷时,偏置燃烧室的柴油机雾化出现雾化不均匀,缸内气流运动较燃烧室不偏置的柴油机有了较大变化。试验结果表明：在高速、高负荷的工况下,不偏置型的燃烧室较偏置燃烧室型油耗要低很多。
[Abstract]:After the Industrial Revolution, human beings consumed non-renewable energy in nearly a hundred years, resulting in energy shortage and environmental deterioration. Diesel engine is also a link to promote the progress of human civilization, so the research and development of more economic and environmental protection and strong power diesel engine has a great prospect. For the direct injection diesel engine, the gas flow in the cylinder and the formation of the mixture play an important role in the combustion and pollutant emission. Although electronic control technology can provide the best fuel injection according to the working conditions of diesel engine, the injection pressure is not affected by the speed of internal combustion engine. But considering the working environment, the cost is based on the maintenance cost and other factors. At present, the power economy of non-road small agricultural diesel engine is improved by improving the movement of in-cylinder air flow and improving the quality of combustible mixture. Because of the lightweight design of GD190 single-cylinder diesel engine, the design layout on the cylinder is very close, so it will be convenient for the design of the cylinder to determine the basic size of the injector through the estimation of the design index. In this paper, the size of injector injection hole is estimated at first, and the calculation model of injector and combustion chamber is established by CFD software AVL FireESE module. Then, the full model is established by using AVL Fire software to obtain the effects of injection hole cone angle, nozzle depth and combustion chamber bias on combustion. The simulation results show that for high speed and short stroke single cylinder diesel engine, under the same injection pressure, injection hole diameter and combustion chamber, it is necessary to match the injector with large injection hole cone angle, and the installation depth of the injector needs to be deeper. When the nozzle cone angle is too small, the tangential force of the oil beam can not be matched with the air flow flowing from the cylinder ring into the combustion chamber to form a vortex conducive to the atomization of fuel steam. However, the fuel injection nozzle has a small installation depth, which makes the fuel steam attached to the top of the cylinder head easily, which is not conducive to combustion. When the angle of the fuel beam and the installation depth of the nozzle remain unchanged, the combustion chamber is shifted to the piston center by 5 mm, and the injector is still installed directly above the combustion chamber. The simulation results show that at 2600r / min, the atomization of the diesel engine with bias combustion chamber is uneven, and the air flow in the cylinder is much different from that of the diesel engine without bias in the combustion chamber. The experimental results show that the fuel consumption of the unbiased combustion chamber is much lower than that of the bias combustion chamber under the condition of high speed and high load.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK423

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