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首页> 外文会议>American Society of Mechanical Engineers(ASME) Internal Combustion Engine Division Fall Technical Conference; 20050911-14; Ottawa(CA) >SIMULATION OF AN AUTOMOTIVE CATALYTIC CONVERTER INTERNAL FLOW
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SIMULATION OF AN AUTOMOTIVE CATALYTIC CONVERTER INTERNAL FLOW

机译：汽车催化转化器内部流动的模拟

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摘要

Catalytic converters have been used for a number of years in the United States to control automotive pollution. A catalytic converter needs to reach a certain temperature before the chemical reactions take place (light-off). Recently, the new regulations on emission standards have prompted a reconsideration of the design of automotive catalytic converters in order to reduce the light-off period of the catalyst. The catalytic converter light-off period is very Important since almost 80% of the emissions from vehicles occur within the first three minutes after cold start in the FTP-75 test. In order to meet these new regulations, current studies have suggested that the catalyst should be "close-coupled"; that is fitted close to the engine exhaust manifold. In order to design "close-coupled" converters, the designer may have to resort to truncated inlet and outlet cones, or distorted inlet pipes due to space limitations. Hence, it is very difficult to achieve good mixing of the exhaust gas, and a good flow distribution at the inlet cross section of the monolith. Based on such a current status in the study of the catalytic converter, the present work focuses on the time-dependent flow patterns, both in the exhaust manifold and the catalytic converter using Computational Fluid Dynamics (CFD). A three-dimensional grid model of an engine exhaust manifold and a close-coupled catalytic converter was developed and analyzed. The flow simulations were performed using KIVA-3 for non-reacting flow fields. These simulations were performed with transient boundary conditions applied at the inlet to the exhaust runners to simulate the opening and closing of exhaust valves. The CFD results were used to study flow uniformity under different operating conditions and to identify the best location for the oxygen sensor.
机译：催化转换器在美国已用于控制汽车污染多年。在发生化学反应（起燃）之前，催化转化器需要达到一定的温度。最近，有关排放标准的新法规促使人们重新考虑汽车催化转化器的设计，以减少催化剂的起燃时间。催化转化器的起燃期非常重要，因为在FTP-75测试中冷启动后的前三分钟内，车辆产生的排放几乎有80％。为了满足这些新规定，目前的研究表明催化剂应该是“紧密耦合的”。安装在发动机排气歧管附近。为了设计“紧密耦合”转换器，由于空间限制，设计人员可能不得不诉诸于截断的入口锥和出口锥或变形的入口管。因此，很难实现废气的良好混合，并且在整料的入口横截面处实现良好的流量分布。基于催化转化器研究中的这种当前状态，本工作着重于时间相关的流型，无论是排气歧管还是使用计算流体动力学（CFD）的催化转化器。建立并分析了发动机排气歧管和紧密耦合催化转化器的三维网格模型。使用KIVA-3对非反应流场进行流动模拟。这些模拟是通过在排气流道的入口处应用瞬态边界条件来进行的，以模拟排气门的打开和关闭。 CFD结果用于研究不同操作条件下的流量均匀性，并确定氧气传感器的最佳位置。

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