发动机进气系统的CFD分析及实验研究.doc
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1、 硕士学位论文发动机进气系统的 CFD 分析及实验研究THE ANALYSIS AND EXPERIMENTAL STUDY OF THE ENGINE INTAKE SYSTEM BASED ON CFD郭伟哈尔滨工业大学 2012年 7月国内图书分类号:U464.134+.4 学校代码: 10213 国际图书分类号:629密级:公开工程硕士学位论文发动机进气系统的 CFD 分析及实验研究硕士研究生:郭伟 导 师:罗丽君 副教授 申请学位:工程硕士 学科:车辆工程 所 在 单 位:汽车工程学院 答 辩 日 期: 2012 年 7 月 授予学位单位:哈尔滨工业大学Classified Inde
2、x: U464.134+.4 U.D.C: 629Dissertation for the Master Degree in Engineering THE ANALYSIS AND EXPERIMENTAL STUDY OF THE ENGINE INTAKE SYSTEM BASED ON CFDCandidate : Guo Wei Supervisor : Associate Prof. Luo Lijun Academic Degree Applied for : Master of Engineering Vehicle Engineering Specialty : Colleg
3、e of Automobile Engineering Affiliation : July, 2012 Date of Defence : Degree-Conferring-Institution : Harbin Institute of Technology哈尔滨工业大学工程硕士学位论文 摘 要 发动机进气歧管与进气道是发动机进气系统的重要组件之一,其进气性能的好坏将直接影响发动机缸内可燃混合气的形成及燃烧火焰的传播。因此,一台性能优良的发动机离不开良好的发动机进气歧管与进气道形状。 在传统的进气系统的设计过程中,主要依靠设计人员经验以及稳流实验,但这种方法周期长、成本高,因此,本文使
4、用 CFD的方法对发动机的进气系统进行分析,为进气系统的结构设计和改进提供依据。本文使用新一代流体分析软件STAR-CCM+对发动机进气歧管及进气道内的气体流动进行了计算。首先,使用90T 形管模型验证了网格形状、边界层的划分以及模板方向对计算结果的影响,为仿真计算过程中网格划分提供依据。其次,对某两台发动机的进气歧管分别进行建模计算,分析歧管内的流场分布以及压力损失,并将计算流量与实验结果进行对比验证。昀后,对某发动机螺旋进气道模型进行了三维模拟,分析缸内压力、速度分布以及湍动能的分布,然后获取流量、涡流比数据与实验结果进行对比,验证 CFD 模拟计算发动机进气道的准确性。 研究结果表明:在
5、 CFD计算过程中,不同的网格形状、边界层层数以及模板方向都会对计算结果产生影响,采用正六面体网格、边界层两层的网格划分方式能够较快收敛且有比较高的计算精度;通过对进气歧管的计算发现,计算结果能充分反映歧管内的流场信息,在入口与稳压腔连接处、稳压腔与支管连接处速度与压力发生突变,符合流体力学的基本理论,将计算流量、压降等与实验结果进行对比,计算与实验存在一定误差,主要原因是实验设备的误差及计算模型与实验模型之间可能存在误差;对进气道进行 CFD计算,分析缸内流场信息,将计算流量及涡流比与实验结果进行对比,两者之间误差低于 5%,充分验证了 CFD 计算的可靠性。 本文通过对发动机进气系统的 C
6、FD数值模拟计算与稳流实验相结合,验证了CFD 计算的准确性,为发动机进气系统的设计及结构优化提供了一种快速、有效的方法。关键词:进气歧管;进气道;流场分析;实验验证I 哈尔滨工业大学工程硕士学位论文 Abstract The engine intake manifold and intake port are important components of the engine air intake system. The performance of the system will directly influence the formation of the inflammable mi
7、xture and the spread of the combustion flame in the cylinder. Therefore, an excellent engine need to design good engine intake manifold and intake portIn the traditional design process of air intake system, it mainly rely on the personal experience and the steady flow experiment, but this method nee
8、d long time and high cost. Therefore, the CFD method is used to analyse the flow field of the engine intake system to provide the basis for the design and improvement of the structure of the air intake system. The air flow in the intake manifold and intake port was calculated in the thesis by using
9、the fluid analysis software STAR-CCM+. Firstly, a 90 T-junction model was used to validate the effection of the grid model, the boundary layer and the direction of the template on the calculated results, it provides the basis for meshing in the simulate calculation process. Secondly, three-dimension
10、al geometric model of two engines intake manifold was established and simulated, then further analysis about the flow field and pressure loss was done and the difference of the mass flow rate between the simulation and the experiment was compared. Finally, three-dimensional geometric model of engine
11、s intake port was established and simulated, then the distribution of the pressure, velocity and turbulent kinetic energy was analysed. Also, the mass flow rate and swirl ratio data was obtained and compared with the experimental results to verify the accuracy of the simulationThe results of the stu
12、dy showed that: In the process of the CFD simulation, different grid shapes, boundary layers and the direction of the template will effect the calculation results, the positive hexahedral grid, two boundary layer grid mesh could be converged faster and get higher calculation accuracy; through the ca
13、lculation of the intake manifold, we found that the calculation results can fully reflect the information of the flow field in the manifold, the pressure and the velocity change fiercely in the port between the entrance and the pressure stabilizing cavity and the port between the pressure stabilizin
14、g cavity and the branch pipe. The result complied with the basic theory of fluid mechanics. Compared the results of the calculation and the experiments, we found some deviation. The main reason is the accuracy of the experimental equipment and the difference between the calculation model and the exp
15、erimental model. Analysed the result of the CFD simulation of the intake port and compared the swirl ratio between the simulation and the experiment, we found that the deviation was II 哈尔滨工业大学工程硕士学位论文 less than five percent. We fully verified the reliability of the CFD simulationThe accuracy of the
16、CFD calculation was verified in the thesis through the comparison of the CFD simulation and the steady flow experiment of the intake systemA quick and effective research method for the design and structure improvement of the intake system is proposed in the thesis Keywords: intake manifold, intake p
17、ort, flow field analysis, experimental verification III 哈尔滨工业大学工程硕士学位论文 目 录 摘 要?I Abstract ? II 第 1 章 绪 论 ? 1 1.1 课题背景及研究意义 ? 1 1.2 国内外研究现状 ? 2 1.2.1 国外研究现状? 2 1.2.2 国内研究现状? 3 1.3 本文研究内容 ? 4 第 2 章 计算流体动力学的数学模型? 6 2.1 流体动力学控制方程 ? 6 2.1.1 质量守恒方程? 6 2.1.2 能量守恒方程? 7 2.1.3 动量守恒方程? 7 2.2 控制方程的离散方法 ? 8 2.3
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