二冲程气道喷射式液压自由活塞发动机喷射方式分析及优化仿真  

Injection mode analysis and optimization simulation of two-stroke port injection hydraulic free piston engine

作　　者：李常铭 汪洋[1] 耿鹤鸣 李智勇 董翔宇 甄旭东[2] LI Changming;WANG Yang;GENG Heming;LI Zhiyong;DONG Xiangyu;ZHEN Xudong(State Key Laboratory of Engines,Tianjin University,Tianjin 300072,China;School of Automobile and Transportation,Tianjin University of Technology and Education,Tianjin 300222,China)

机构地区：[1]天津大学内燃机燃烧学国家重点实验室,天津300072 [2]天津职业技术师范大学汽车与交通学院,天津300222

出　　处：《武汉大学学报（工学版）》2021年第3期255-262,共8页Engineering Journal of Wuhan University

基　　金：国家自然科学基金项目(编号:51476113,51776135,51406135)。

摘　　要：为降低二冲程液压自由活塞发动机(hydraulic free piston engine,HFPE)使用气道喷射方式时的燃油消耗,将喷油器置于气道内扫气口处,使用CONVERGE软件建立了从燃油喷射过程到混合气生成过程的三维计算流体动力学仿真模型,研究了燃油喷射相位、喷射角度以及喷油器流量大小对混合气生成过程的影响。结果表明:燃油喷射角度越小、喷射相位越晚,燃油捕集率越高,最高可达99%,比新鲜空气捕获率高出39%,燃油消耗率降低较大;燃油喷射角度过大或过小,都会恶化燃油的气化效果,最佳的燃油喷射角度(与缸头法线方向夹角为43°~48°)可以获得最高的燃油气化率,但较早的喷射相位会使油束在缸内的实际流动方向发生改变,增加缸壁油膜的生成量,降低燃油气化率;大流量的喷油器在最佳的喷射角度上拥有更好的燃油捕集和气化效果,同时对应效果较好的喷射相位区间宽度大于小流量喷油器,喷射灵活性更佳。In order to reduce the fuel consumption of two-stroke hydraulic free piston engine(HFPE)using the port injection mode,the injector was placed at the scavenging port.A three-dimensional computational fluid dynamics simulation model of the process from the fuel injection to the mixture generation was established by using CONVERGE software.The effects of fuel injection phase,injection angle and injector flow rate on the mixture forming process were investigated.The results show that the smaller the fuel injection angle and the later the injection phase are,the higher the fuel capture rate.The highest fuel capture rate can reach up to 99%,which is 39%higher than the fresh air capture rate,so the fuel consumption rate decreases greatly.If the fuel injection angle is too large or too small,the gasification effect of the fuel will be deteriorated.There is an optimal fuel injection angle(43°~48°)with the normal direction of cylinder head,and the highest gasification rate can be obtained by injection at this range.Earlier injection phase will change the actual flow direction of the fuel in the cylinder,increase the production of the oil film on the cylinder wall and reduce the fuel gasification rate.Compared with small flow rate injector,the larger flow rate injector has better fuel capture and gasification effect at the optimum injection angle,the width of injection phase interval with better corresponding effect is larger,and the injection flexibility is better.

关 键 词：液压自由活塞发动机 二冲程气道喷射 燃油捕集 混合气生成 

分 类 号：TK411[动力工程及工程热物理—动力机械及工程]