摘要
利用进气行程排气门二次开启实现排气回流,并通过排气门行为参数和滚流强度的改变对回流废气的缸内分层分布进行主动控制.为探究不同影响因素下回流废气缸内分布的规律性,在一台滚流气道单缸光学发动机上应用平面激光诱导荧光法测量了不同排气门二次开启规律、不同进/排气压差以及增强滚流等条件下回流废气在不同曲轴转角的分布状态.结果表明:排气门二次开启时刻在进气行程中后期时,回流废气会随着缸内已形成滚流运动沿燃烧室外围产生旋转运动,在近点火时刻保持回流废气与新鲜空气的分层分布状态;排气门二次开启时刻在进气行程前期时,由于缸内未形成有效的滚流运动,回流废气过早进入气缸基本形成均匀混合气;进气行程中后期较高的排气门二次开启升程仍能形成良好的EGR分层状态,并且还能起到减缓滚流旋转运动的作用;进/排气压差过大时,回流废气量较大,废气气流运动也较强,不易于产生EGR分层;较强的滚流运动可以加快回流废气缸内旋转速度,相同的曲轴转角内产生更大的转移幅度.
Exhaust gas backflow was achieved with exhaust valves re-opening during the intake stroke,and the backflow exhaust gas can be separately controlled with fresh air by regulating the exhaust valves movement and tumble intensity.Planner laser induced fluorescence experiments were conducted on an optical single cylinder engine with tumble inlet port to explore the distribution characteristics of the refluent exhaust gas in cylinder under different influenced factors,such as dual exhaust valves opening strategies,pressure difference between inlet and exhaust port,and stronger tumble motion.The results showed that backflow exhaust gas rotating along the cylinder outer with the formed tumble motion during exhaust valves re-opening at late inlet stroke,and keeps separately with fresh air prior to the ignition.The backflow exhaust gas mixes homogeneously with air due to uneffective tumble motion when the second exhaust valves are openned in early inlet stroke.In later inlet stroke,good stratified EGR can be realized with exhaust gas backflow.High lift plays an extra role in suppressing the tumble intensity.Large amount and strong flow of exhaust gas was brought by the large pressure difference between inlet and outlet port,which is hard to generate the stratified EGR condition.The backflow exhaust gas rotational speed is accelerated with the enhanced tumble,and larger movement is presented within the same crankshaft angle.
出处
《内燃机学报》
EI
CAS
CSCD
北大核心
2016年第3期253-259,共7页
Transactions of Csice
基金
国家自然科学基金资助项目(51276080)
吉林省科技引导计划青年科研基金资助项目(20140520128JH)
关键词
光学发动机
激光诱导荧光法
排气门二次开启
排气回流
optical engine
planner laser-induced fluorescence
dual exhaust valves opening
exhaust gas backflow
