基于微遗传算法的船用柴油机喷油策略优化及研究

Numerical Simulation and Optimization Study of Injection Parameters for a Marine Diesel Engine Based on Micro Genetic Algorithm

为优化大型船用柴油机的燃油喷射策略,采用微种群遗传算法结合三维数值模拟,在一台大缸径低速船用柴油机上对两个喷油器的主喷时刻、预喷间隔和预喷比例进行了优化,并在优化算例的基础上研究了大型船用柴油机各个喷油器预喷参数和顺序喷射对性能与排放的影响。研究结果表明,在采用顺序喷射的前提下,顺序喷射间隔影响NOx排放和指示燃油消耗率。第一个和第二个喷油器的预喷策略对大型船用柴油机的性能与排放有不同的影响,前者是预喷放热与主喷滞燃期缩短综合作用的结果,而后者主要是预喷放热自身的影响。通过以上研究和优化,柴油机的NOx排放降低了21.27%,表明该方法可以用于优化大型船用柴油机的喷射策略。

To investigate the fuel injection strategy for large low speed marine diesel engines, a micro genetic algorithm coupled with 3 D numerical simulation was applied to the optimization of start of injection timing{SOD, pilot injection interval and pilot fuel fraction of two injectors. The effect of the pilot injection parameters and sequential injection of each injector on engine performance and emissions was further investigated based on the optimized case. Results show that for the sequential injection operation the injection interval between two injectors has some impact on NO- emissions and indicated specific fuel consumption （ISFC）, while the pilot injection strategy of the first and second injectors has different effects on engine performance and emissions： the former is the result of the combined effects of the pilot fuel heat release and shortened ignition delay of main injection ,while the latter is mainly due to the pilot fuel heat release itself . Through the above study, the NO- emissions have been reduced by 21.27%,which proves that this method can be used to optimize the injection strategy of large marine diesel engines.