B发动机进气系统设计及分析

课程论文

题 目：B15发动机进气系统设计及性能分析

学生姓名：

学 院：能源与动力工程学院

班 级：交通运输09-3

指导教师：高志鹰 副教授

2018年12月28日

内蒙古工业大学课程设计<论文）任务书

汽车电子控制技术

学院：

课程名称：

能源与动力工程学院

交通运输

班级：

___

学生姓名：

学号：

指导教师：

200

高志鹰

摘要

近年來,随着经济的发展,汽车行业也发生了日新月异的变化。目前,对发动机的设计除了要达到汽车的动力性、经济性指标外,还需要满足其排放及噪声的要求,因此有必要对发动机的进排气系统进行深入的研究。进气系统主要包括进气歧管前的管路和进气歧管两部分,其中歧管前的管路起降低进气噪声的作用。如何合理的设计进气系统的元件,分析其综合性能,是目前工程工程中研究较多的课题。

首先,本文介绍了可变气门正时与可变进气歧管技术的原理,在GT-Power软件中建立B15发动机模型,并利用实验数据完成模型的标定,使其误差不高于5%,以用于后续的仿真计算。为了设计进气系统的消声元件,对赫姆霍兹谐振腔、1/4波长管和空气滤清器的参数灵敏性进行计算分析,总结参数变化对消声性能的影响规律。详细阐述进气消声元件的设计流程和方法,提出具体的设计方案,并针对方案中某转速下个别阶次噪声高于目标值的问题,对消声元件进行优化。优化后的进气系统进气口噪声明显改善,压力损失不高于 2.5kPa,符合目标值要求,优化效果良好。

其次,为了分析进气歧管的性能,本文提出3种方法:利用零维或一维模型做简化处理、利用CFD软件完成稳态或孤立瞬态的计算以及利用一维和三维软件进行耦合分析。通过比较3种方法的优劣,发现利用软件的耦合可以在计算过程中获得实时的边界条件,有较高的准确度。本文重点阐述利用GT-Power件和STAR-CCM+软件进行耦合设置需要解决的关键问题,并在此基础上完成模型的计算。

最后,为了更好的评价进气消声元件的优劣,利用GT-Power软件中耦合后的模建立汽车加速行驶车外噪声仿真模型,计算得到进气系统的最大噪61.8dB(A>,其对通过噪声的单独贡献率满足目标要求。

关键词:进气系统；消声元件；加速行驶车外噪声；仿真与优化

ABSTRACT

With the development of economy, the automobile industry has been changingwith each passing day. At present, the design of enginesmust meet the criteria of emission and noise level besides the power performance andeconomy, which makes it very necessary to make an exhaustive study on engineintake and exhaust systems. The intake system is made up mainly by inlet manifoldand the pipe before inlet manifold. The pipe before inlet manifold can cut down theinduction noise. How to design the intake system components and analyze thecombination property is a topical issue of the current engineering projects.

Firstly, the principles of variable valve timing and variable intake manifold areintroduced, then the simulation model of B15 engine is established in GT-Power, afterwhich the model is calibrated by the test results and the error is less than 5%-This layspreliminary groundwork for the subsequent calculation, the parametric sensitivity ofHelmholtz resonator, 1/4 Wave tube and air cleaner is calculated, and the influence ofparameter changing on Acoustic attenuation performance is summarized, based onwhich the silencer elements of intake system are designed. The design procedure andmethod of silencer element are explained thoroughly, and the detailed design schemeis put forward.

Secondly, three methods are put forward in this thesis to analyze the performanceof inlet manifold,and they are simplified simulation built up with zero or onedimensional models, steady or transient calculation by CFD and coupled simulationby one dimensional with three dimensional software. After the comparison of thesethree methods, it is found that the coupling process can provide more accurateboundary conditions for the calculation. The problems of coupling between GT-Powerand STAR-CCM+ are solved, and then the simulation is carried out. Then the velocity field of everybranch pipe in different time is analyzed, and the suggestion is that the curvature ofthe branch pipe should be reduced.

Lastly, in order to evaluate the performance of the silencer elements, theacceleration running noise model is built up based on the coupling model. The resultshows that the noise of the intake system is lower than 61.8dB(A>,which satisfies thedemand for contribution rate to the acceleration running noise.