【作者】 张超；

【导师】 左承基；

【作者基本信息】 合肥工业大学 ， 动力机械及工程， 2010， 硕士

【摘要】 大气污染已经成为当今世界面临的一个难题,它会破坏生态系统和人类正常生存和发展的条件。大气污染的主要来源之一是汽车发动机,用仿真软件可以研究发动机排放生成机理,分析发动机参数对排放的影响,为降低发动机排放提供理论依据。CFD软件是目前国际上进行传热、传质、动量传递及燃烧、多相流和化学反应研究的有效工具,而FLUENT是目前功能最全面、使用最广泛的CFD软件之一。本文对ZS195柴油机进行了燃料重整模拟计算,分析了在不同的模拟重整气下的柴油机气缸内部流场、湍流动能分布、温度分布、氧气浓度分布、柴油浓度分布、NOX浓度分布、碳烟排放浓度分布以及平均压力和温度分布。结果表明:掺CO后,柴油机的NOX排放增加,碳烟排放降低,NOX和碳烟的模拟值和试验值比较接近;掺H2、CO以及EGR后,可以同时降低柴油机的NOX和碳烟排放。目前大型数值模拟用串行计算需要花费大量的时间,而采用并行计算有可能提高FLUENT软件模拟计算的速度。本文测试了各种并行计算方案对模拟计算速度提高的影响。结果表明,模拟计算量小的时候,并行计算不能明显地能够提高模拟计算的速度。模拟计算量大的时候,并行计算可以较明显地提高模拟计算的速度。LINUX系统的并行计算性能要好于WINDOWS XP系统的并行计算性能。计算机主频越高,并行计算性能越好。更多还原

【Abstract】 The air pollution already become a problem of the world, it destroy the ecosystem and the condition of human survival and development normally. The engine is one of main sources of it. It can study the production mechanism of emissions with the simulation software, analyzes the emissions with different engine conditions, provide the theory basis to reduce the engine emissions. The software of CFD is the effective tool of the heat transfer, the mass transfer, the momentum transfer and the combustion, the polyphase flow and the chemical reaction research, and FLUENT is one of the software which has most comprehensive function and wide application.Simulates fuel reformed of ZS195 diesel, analyzes the distribution of in cylinder flow field, turbulent kinetic energy, temperature, oxygen, diesel oil, NOX, soot, average pressure and average temperature. The result shows that the NOX emission increases and the soot emission reduces after mixing CO. Simulation value is close to experimental value. The NOX emission and soot emission reduce simultaneously after mixing H2, CO and EGR. The large-scale computation needs to cost many time with the serial computing now.However it may enhance the computation speed of the FLUENT with the parallel computing. This article has tested the influence which each kind of parallel computing plan enhances the computation speed. The result shows that the parallel computing can not increase the computing speed obviously when amount of calculation is small. But it can when amount of calculation is big. The LINUX system is better than the WINDOWS XP system for the performance of parallel computing. The computer dominant frequency is higher, the parallel computing performance is better.更多还原