活塞形状对点燃式天然气发动机性能的影响

摘要

结合天然气发动机的性能优化,在一定压缩比下,设计了两种不同形状的燃烧室,对缸内气体流动及燃烧过程进行了数值模拟,并在台架上进行了试验验证.模拟得出了不同结构燃烧室的湍动能、火焰前锋面位置、燃烧放热率等,结果表明,中心凹陷燃烧室效果较好,与中心凸起燃烧室相比,产生的湍流强度较大,燃烧速度更快,克服了天然气燃烧速度慢的缺点,因此动力性和经济性较好,然而NO排放量也较大.%Combining the performance optimization of NG engine,two different combustion chambers were designed with a constant compression ratio.The numerical simulation of in-cylinder gas flow and combustion process was carried out and verified on the test bench.The turbulence kinetic energy,flame front surface position and heat release rate of different combustion chambers were acquired by the simulation.The results show that,compared with the combustion chamber with bulge center,the combustion chamber with cup centre has better combustion process due to the higher turbulence intensity and the faster burning rate which compensates the slow NG burning rate.Accordingly,the power performance and fuel economy of combustion chamber with cup center are better,but its NO emission is higher.