直喷汽油机多孔喷油器喷油过程的数值模拟  

Numerical Simulation of Fuel Injection Processes of a Multi-Hole Injector for Direct Injection Gasoline Engines

作　　者：李之华[1] 何邦全[1] 赵华[1] 

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

出　　处：《内燃机学报》2012年第3期241-247,共7页Transactions of Csice

基　　金：国家高技术研究发展计划"863"资助项目(2006AA110107)

摘　　要：针对直喷汽油机多孔喷油器的喷油过程,基于通用计算流体力学三维数值模拟软件Star-CD,建立了一种燃油复合破碎模型.其中,一次雾化采用Huh-Gosman模型与KH模型竞争的方法进行模拟;分裂长度之后的二次破碎采用RT模型与一次雾化机理竞争的方法进行模拟.应用该模型,对定容弹内多孔喷油器在不同喷射压力和背压下的喷油过程进行了研究.结果表明,在喷油初期以及喷口附近,喷口内部产生的湍流对燃油雾化破碎起主导作用,此后喷口湍流的作用逐渐被气动力因素所取代.在喷射压力一定时,背压越大,以破碎液滴数计量的破碎强度越低,由气动力诱发的破碎出现越早、强度越高.在背压一定时,喷射压力越高,以破碎液滴数计量的破碎强度越高,强度的增加程度与喷油时的背压有关,由气动力诱发的破碎也随喷射压力的提高出现得更早、强度更高.To study the injection processes of a multi-hole injector for gasoline direct injection（GDI） engines, a hybrid droplet atomization and breakup model was developed based on the commercial code Star-CD. The primary breakup process of spray was simulated by the competition between the Huh-Gosman and KH mechanisms, and the secondary breakup was simulated by employing the RT model as a third competing mechanism beyond spray breakup length. By using this hybrid model, fuel injection processes of a multi-hole gasoline injector were numerically studied under different injection and ambient pressures. Results show that, the breakup due to turbulence at the nozzle exit dominates the initial injec- tion stage. As this turbulence gradually decreases, part of the breakup is induced by the aerodynamic force around the spray. At fixed injection pressure, an elevated ambient pressure leads to a decreased breakup in terms of the breakup droplet number. Aerodynamically induced breakup occurs earlier and intensified. At fixed ambient pressure, higher injection pressure can lead to an increase in breakup intensity, and the extent depends on the ambient pressure. Aerodynamically induced breakup occurs earlier and intensified with the increase of injection pressure.

关 键 词：汽油 多孔喷油器 雾化破碎 数值模拟 

分 类 号：TK412.2[动力工程及工程热物理—动力机械及工程]