汽车的尾气已经成为我国城市的最主要的污染物之一。车辆排放的污染物主要来自于发动机，主要的污染物有CO,HC,NOX,PM,SO2等，其中汽油机的主要污染物是前三种。日益严格的排放法规对汽车的的排放提出了很高的要求，如果只依靠机内净化和发动机前处理是不够的，催化转化器能减少排放物中的有害成分，是目前最有效的尾气排放控制装置。三元催化装置越来越受到了人们的重视，三元催化转化器（TWC）已经广泛地运用到了汽车上。 催化转化器的传统研究手段是实验研究，随着计算机技术的发展，出现了另一种十分有效且节约成本的研发手段——数值模拟。     
紧耦式排气歧管与三元催化器等后处理装置直接连接，排气歧管出口处气流分布的均匀性会影响后处理装置的处理效率，进而影响后处理的效果。本文利用CFD方法对某汽油机排气歧管中的内流场进行了模拟分析，重点考虑了歧管出口表面的气流分布均匀性，并对氧传感的位置进行了评估，获得了良好的效果，对产品开发有一定的指导意义。  8946
关键词：排放控制;三元催化转化装置；CFD；模拟分析
Title Design of Oxygen sensor and Three-Way catalytic
       Converter match with Tight coupled type exhaust manifold
Abstract
 The harmful emissions from the automobile have become a main pollution
of  the atmosphere in most cities of our country. It comes from I.C engine，
including carbon monoxide(CO) ,carbon hydrogen compound(HC)，the nitrogen
oxygen compound(NOx) ， particulate material(PM) and the  sulfur
dioxide(S0)etc. And the CO，HC，NOx are the main Polluting compositions
of gasoline automobile exhaust gas. The requirement of the automobile
emission indicates that only depending on disposition before engine and
purification in the engine can't satisfy with the exhaust regulations which
become more and more stringent.  As the most efficient way that reduces the
waste gas of the automobile emission，the catalyst conversion technology
has been emphasized in many countries，especially the three-way catalyst
converter.
 Test is a traditional method, which can give necessary message to the
research and development of catalytic converter, but it can’t show the
heat and mass transfer and internal flow in catalytic converter. With the
development of computer technology and the maturity of numerical model of
catalytic converter, another method-- numerical simulation is available.
 The exhaust manifold of small gasoline engines is usually connected
to a three way catalyst converter, the evenness of fluid at outlet may
affect the performance of catalyst converter. This paper discusses the
application of the CFD method in simulation of internal flow for exhaust
manifold ,gives an emphasis on the uniformity of fluid homogenization at
outlet, and evaluates the position of the oxygen sensor . Results showed
that the improved model was better than the old one and gives an emphasis
on the evenness of fluid homogenization at outlet .
 
 
Keywords:  emission control,  Three-way catalytic  converter,  CFD,
simulation analysis 目  录
一、绪论..  1
1.1研究背景    1
1.2 CFD技术在发动机排气系统中的应用    3
1.2.1简介  .  3
1.2.2 CFD原理    3
1.2.3 CFD技术在国内外的应用状况    4
1.2.4 CFD技术发展与展望  ..  5
1.3本课题的研究目的和内容  .  5
1.3.1研究目的    5
1.3.2研究内容    6 匹配某发动机紧耦式排气歧管的氧传感器与三元催化设计:http://www.youerw.com/jixie/lunwen_7495.html