天然气发动机点火室结构优化模拟研究

为改善大缸径稀燃天然气发动机的点火可靠性,在一台缸径为320mm的点火室式天然气发动机上,应用三维CFD软件CONVERGE进行了数值模拟,分析了点火室喷孔个数、锥形喷孔以及中心喷孔对天然气发动机燃烧和排放性能的影响。研究表明:7孔点火室火焰射流分布更为均匀合理,且在功率和排放上都优于原机;锥形喷孔方案有利于提高火焰射流的贯穿距,提高功率和热效率,并降低NOX排放;中心喷孔方案的优化效果与中心喷孔的直径有关,中心喷孔直径为1.5mm和2.5mm时,可以提高发动机功率并降低NO_X排放。

Study on Structural Optimization Simulation of Ignition-chamber for Natural Gas Engine

In order to improve the ignition reliability of the large-bore lean-burn natural-gas engine,a natural-gas engine with a bore of 320 mm was simulated by using CFD software CONVERGE,and the impact of the orifice number,conical orifice and central orifice on the combustion and emission performance of the natural gas engine was analyzed.The study shows that,the distribution of the flame jet in the 7-orifice ignition chamber is more uniform and reasonable,and both in power and emissions are better than the original machine;The conical orifice can improve the penetration of the flame jets,improve power and thermal efficiency,and reduce NOx emissions;The optimization effect of the central orifice is related to the diameter of the central nozzle,and when the diameter of the central nozzle is 1.5 mm and 2.5 mm,the engine power can be improved and NOx emission can be reduced.