小型柴油机试验台建设及其仿真模型验证

发布时间：2018-10-23 14:51

【摘要】：随着能源危机的加深和排放法规的日益严苛,国内各大汽车和发动机厂家都加快了节能减排的步伐。小型农用柴油机的燃烧性能较差,氮氧化物、碳烟等污染物排放高,为了能够达到排放标准,必须要改进其工作性能。为此,需要通过相应试验测试小型柴油机的动力性、经济性等性能指标,并通过仿真分析其循环工作过程变化,以便对改善发动机性能提出相应改进意见。本文以某厂生产的非道路移动机械用小型柴油机为基础,根据试验台的基本要求和主要功能,完成对试验台的总体设计和试验台建设,完成试验台的安装和调试,对试验发动机在不同工况下的动力性、经济性和排放性进行了相关测试和分析。通过逆向工程得到发动机的气道和燃烧室模型,分别基于AVL BOOST和AVL FIRE软件建立柴油机的一维和三维仿真模型,并根据试验测试结果,对仿真模型进行验证,并对气道流动、喷油、燃烧过程进行了初步分析。论文的主要研究内容及结论如下:1)根据试验发动机相关性能参数和试验目的,确立试验台的基本要求和主要功能,完成对试验台的总体设计,考虑到试验台建设经费有限,确定采用外购加自主设计相结合的方法进行试验台建设;2)对试验台各元器件进行选型、自主设计。简要介绍测功机、油门执行器、缸压传感器、NOx分析仪等测量与控制元件的原理并完成了选型,简述了软件系统的功能,对发动机底座、弹性联轴器、编码器支架等机械元件提出多种方案并根据实验效果确定较优设计方案,对油路辅助系统、排气系统完成设计和加工;3)对试验台进行安装与调试,并完成相关性能测试。主要完成了扭矩标定、油门零度/满度标定、基准压力标定、上止点位置标定等调试工作,然后进行外特性、调速特性和排放特性试验,并通过Matlab软件对示功图进行快速傅里叶变换滤除干扰信号;4)通过逆向工程得到试验柴油机内部流场模型,应用AVL BOOST软件建立一维模型,并根据实验数据进行了验证,以一维模型的部分仿真结果作为初始条件和边界条件,应用AVL FIRE软件建立了三维仿真模型,分析了螺旋气道对缸内流场的影响,证明了螺旋气道有助于改善缸内气流流动状态,然后对柴油机的喷雾、燃烧性能进行了分析,为后续柴油机性能分析及改进奠定基础。
[Abstract]:With the deepening of the energy crisis and the increasingly stringent emission regulations, domestic automobile and engine manufacturers have accelerated the pace of energy saving and emission reduction. The combustion performance of small agricultural diesel engine is poor and the emission of pollutants such as nitrogen oxide and soot is high. In order to meet the emission standard it is necessary to improve its working performance. Therefore, it is necessary to test the power performance and economy performance of small diesel engine by corresponding test, and analyze the change of cycle working process by simulation, so as to put forward the corresponding suggestions for improving engine performance. Based on a small diesel engine produced by a factory for off-road moving machinery, according to the basic requirements and main functions of the test-bed, the overall design and construction of the test-bed and the installation and commissioning of the test-bed are completed in this paper. The power, economy and emission characteristics of the test engine under different operating conditions were tested and analyzed. The engine port and combustion chamber models are obtained by reverse engineering. Based on AVL BOOST and AVL FIRE software, the one-dimensional and three-dimensional simulation models of diesel engine are established, and the simulation model is verified according to the test results, and the flow of the port is verified. The fuel injection and combustion process were preliminarily analyzed. The main research contents and conclusions are as follows: 1) the basic requirements and main functions of the test bench are established according to the related performance parameters and the purpose of the test engine, and the overall design of the test bed is completed, taking into account the limited funds for the construction of the test bed. It is determined that the test bench is constructed by the combination of external purchase and independent design. 2) the components of the test bed are selected and designed independently. The principle of measuring and controlling elements, such as dynamometer, throttle actuator, cylinder pressure sensor, NOx analyzer and so on, are briefly introduced. The functions of the software system, the engine base, the elastic coupling, and so on are described. Encoder support and other mechanical components put forward a variety of schemes and according to the experimental results to determine the optimal design scheme for the oil circuit auxiliary system exhaust system design and processing; 3) to install and debug the test bed and complete the related performance testing. The debugging work of torque calibration, throttle zero / full degree calibration, benchmark pressure calibration, top-and-off position calibration and so on are completed, and then the tests of external characteristics, speed regulation characteristics and emission characteristics are carried out. The interference signal is filtered by fast Fourier transform with Matlab software. 4) the flow field model of diesel engine is obtained by reverse engineering, and the one-dimensional model is established by AVL BOOST software, which is verified by the experimental data. Taking some simulation results of one-dimensional model as initial condition and boundary condition, a three-dimensional simulation model is established by using AVL FIRE software. The influence of spiral port on flow field in cylinder is analyzed. It is proved that spiral port is helpful to improve the flow state in cylinder. Then, the spray and combustion performance of diesel engine are analyzed, which lays a foundation for further analysis and improvement of diesel engine performance.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK427

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