Laval喷管内高速混合气的流动特性研究与仿真分析

【作者】 张静；

【导师】 姚亚夫；

【作者基本信息】 中南大学 ， 机械设计及理论， 2005， 硕士

【摘要】 汽油发动机燃油混合气流动是一个复杂的流体流动和传热问题,它直接影响发动机的动力性,经济性及排放性能,因此我们对混合气的研究能够改善或解决许多问题。本文应用有限元分析软件对Laval管内的复杂流场进行数值模拟分析和研究,使我们从理论上去探索其流体的流动特点与规律,并在日本小野发动机测试系统上进行台架综合性能实验,所得结果与实验结果吻合较好。本文研究的主要内容如下: 1、引用拟流体假设,对研究对象进行合理的简化及假设,并对研究对象进行压缩性修正,建立两相流体的湍流数学模型; 2、运用大型有限元分析软件ANSYS,得到所研究对象的速度矢量、压力分布、湍流动能(ENKE)分布、温度以及马赫数分布等流体的流动特性; 3、通过仿真模拟得到流场的流动特性,分析这些现象对混合气的混合均匀度产生的影响; 4、采用有限元仿真模拟的研究方法,找到空气补偿装置的最佳补偿位置,使得补偿空气能够加速转捩,增大湍流动能,提高混合气的均匀度,使得汽缸中燃烧更加完全,从而对发动机性能的改善达到最好的效果; 5、进行发动机台架综合性能实验,比较理论与实际情况的吻合程度,并针对现有实验条件提出空燃比调节器的改进方案。更多还原

【Abstract】 It is a question that conducting heat and mixture flowing of a complicated fluid flows of the gasoline engine, it influences directly the power of the engine, economy and discharge performance. So we can improve or solve a lot of problems of the auto industry of our country through mixture research. This thesis uses the finite element method to analyze complicated flowing field of Laval nozzle, make us explore flow characteristic and rule of fluid from the aspect of theory, and conduct a shelf performance experiment using Japanese Xiaoye engine test system. The results of theory matched with experiment very well. The main content that this text studies is as follows:1, The thesis uses imitating hydro-supposition to research the complicated two-phase flow, carry on rationalization revision of compressing and carry on simplifying reasonable and assumption for research object, set up the turbulence mathematics model of the double-phase fluid;2, Use the large-scale finite element analysis software ANSYS to get flow characteristic of the fluid , such as speed vector, pressure distributing, the turbulence kinetic energy (ENKE) distributing, temperature and Mach number distributing of research object.;3, We get the rule of flowing field through artificial simulation. Analyse the influence degree that the phenomena affect the process of mixture shape;4, Adopt the artificial simulation research approach of finite element, has found the best position of the air compensator, this make compensating air can accelerate to zhuanLie, increase turbulence kinetic energy, raise the mix uniformity, make the cylinder burn more complete, thus reach the best result to the improvement of the performance of the engine;5, Through engine platform sets of comprehensive performance experiment, the thesis got the experimental results, such as fuel consumption decreased, the power increase, exhaust emission reduced, the theory and actual conditions are identical better. And propose improvement scheme of the air compensator to the existing experiment condition;更多还原