燃烧室形状对天然气发动机燃烧影响的研究

Influence of Combustion Chamber Shape on CNG Engine Combustion Performance

采用试验及三维数值模拟的方法,研究了圆柱、缩口和敞口等燃烧室形状对CA6SE1—21N天然气发动机燃烧性能的影响规律。验证结果表明:天然气发动机混合气形成及燃烧过程的数值模拟结果和试验结果吻合较好,所选模型适合对天然气发动机进行模拟分析。试验和模拟结果均表明燃烧室形状对火焰传播速度影响较大。在3种燃烧室形状中,缩口燃烧室所对应发动机的燃烧及排放性能最好,圆柱形燃烧室次之,而敞口形燃烧室最差。缩口燃烧室的缩口设计使得该处形成较强的挤流,湍流动能增加且维持期较长,火焰传播速度明显提高,改善了发动机的燃烧及排放性能。

The influence of column shape, reentrant shape and open shape combustion chamber on CA6SE1 21N CNG engine combustion performance was studied by the experiment and three-dimensional model. The results show that the simulated results of mixture formation and combustion process are in accordance with their experimental results, which proves that the model is feasible. The simulation and experimental results show that the chamber shape has great influence on flame propagation velocity. Among the three chamber shapes, the combustion and emission performance of reentrant shape chamber are the best, those of column shape chamber are the second and those of open shape chamber are the worst. The reentrant design of reentrant shape chamber leads to the stronger squish flow, the higher kinetic energy and longer duration of turbulent flow are formed, which promotes the flame propagation, and finally the combustion and emission performance are improved.