基于GT-Power的490柴油机进排气系统的数值仿真与优化研究

发布时间：2018-05-04 05:29

本文选题：柴油机 + 进排气系统　；参考：《华南理工大学》2016年硕士论文

【摘要】：柴油发动机自1892年问世以来经历了一百多年的变化发展,现在已广泛应用于汽车、工程机械以及船舶当中。由于柴油发动机的工作流程是先吸入新鲜空气,然后在燃烧室内与柴油充分燃烧产生能量,最后再排出高温废气,所以其进排气系统的设计对柴油机的性能有直接作用。随着柴油机产品的更新速度的加快和使用要求的提高,传统的设计方法已不能适应现代柴油机的开发需要。应用基于计算机仿真技术的新型设计方法,不仅能快速对设计对象进行评估,而且能大大减少重复性试验的工作量,降低开发成本,缩短开发周期。因此,利用计算机进行数值仿真与优化设计的方法已经成为柴油机开发的新主流设计方法。本文针对所研究的全柴490柴油机,搭建发动机台架试验平台,进行了不同工况下的台架试验,测量得出各个工况下的性能参数。应用一维非定常流体力学理论,在仿真软件GT-Power中建立发动机的数值仿真模型,通过各个稳态工况下仿真得出的数据与台架数据进行对比分析,验证模型的正确性。在此基础上,对进排气系统的三维模型进行离散化,在模型中通过改变进排气系统的各项结构参数,包括进气总管长度、谐振腔容积、进气歧管长度和直径、排气歧管长度和直径以及进排气系统的布置形式,研究分析其对发动机性能,如功率、扭矩、油耗、进气流量、排气压力和排气温度的影响。以进排气系统的各个结构参数为试验因子,利用试验设计(Design of Experiment,DOE)方法,得出一系列性能参数作为试验响应,拟合二阶模型响应面,并以功率和扭矩最大,油耗率最少为优化目标,利用遗传算法进行多目标优化。通过原始参数与取整后的优化参数的输出性能对比,可知功率和扭矩有所提升,同时油耗有所降低。在得到优化参数后,对进排气系统进行三维建模,同时利用Fluent软件进行流场仿真分析,对分析结果提出进一步的结构优化意见,得出最终的进排气结构及三维模型。
[Abstract]:Diesel engine has been developed for more than 100 years since it came out in 1892. Now it has been widely used in automobile, construction machinery and ship. The design of diesel engine intake and exhaust system plays a direct role in the performance of diesel engine because the working process of diesel engine is first to inhale fresh air, then to produce energy in the combustion chamber and diesel fuel, and finally to exhaust the high temperature exhaust gas. With the development of diesel engine, the traditional design method can not meet the needs of modern diesel engine development. The new design method based on computer simulation technology can not only evaluate the design object quickly, but also greatly reduce the workload of repeated experiments, reduce the development cost and shorten the development period. Therefore, the method of numerical simulation and optimization design using computer has become a new mainstream design method for diesel engine development. In this paper, an engine bench test platform is set up for the study of all kinds of diesel engines, and the performance parameters under different working conditions are measured. Based on the theory of one-dimensional unsteady fluid dynamics, the numerical simulation model of engine is established in the simulation software GT-Power. The validity of the model is verified by comparing and analyzing the data obtained from the simulation under various steady conditions and the bench data. On this basis, the three-dimensional model of intake and exhaust system is discretized. In the model, various structural parameters of intake and exhaust system are changed, including intake manifold length, resonant cavity volume, intake manifold length and diameter. The length and diameter of exhaust manifold and the layout of intake and exhaust system are studied and analyzed. The effects on engine performance, such as power, torque, fuel consumption, intake flow rate, exhaust pressure and exhaust temperature, are studied. Taking the structural parameters of the intake and exhaust system as the experimental factors and using the design of experimental design of experimental design method, a series of performance parameters are obtained as the experimental response, fitting the second-order model response surface, and the maximum power and torque are obtained. The minimum fuel consumption rate is the objective of optimization, and genetic algorithm is used for multi-objective optimization. By comparing the output performance of the original parameters with the optimized parameters after rounding, the power and torque are improved and the fuel consumption is reduced. After the optimization parameters are obtained, the three-dimensional model of the intake and exhaust system is built, and the flow field simulation analysis is carried out by using Fluent software. Further structural optimization suggestions are put forward to obtain the final intake and exhaust structure and three-dimensional model.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK423

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