摘要
针对近年来柴油机中广泛采用的双切向进气道布置形式,自行设计、制作了实验用气道芯盒,利用气道稳流实验台研究了气门座圈底孔偏心倒角结构对气道流量系数和涡流比的影响.实验结果表明:偏心倒角对流量系数基本无影响;当标准化气门升程小于0.184,6时,偏心倒角可以大大提高涡流比,且带偏心倒角的各方案间涡流比也存在显著差异;而当标准化气门升程超过0.184,6时,各方案的涡流比变化曲线几乎重合.选取2,mm、9,mm分别代表小、大气门升程,结合CFD技术对气道-气门-缸筒模型进行了三维数值模拟研究.模拟结果显示2,mm升程时,与无偏心倒角方案缸内出现两个反向涡结构相比,偏心倒角可以避免气流间的撞击干涉,使气流在缸内形成同一方向的涡流;而9,mm升程时,有、无偏心倒角方案均在缸内形成了单一的涡结构,二者无显著差异,从而从机理上解释了实验结果.
Aimed at the double tangent intake port layout scheme which is widely adopted in diesel engine in recent years,core box of intake port was designed and manufactured,and an experimental study about effects of eccentric chamfers at valve seats on intake performance of double tangent ports was conducted with steady flow experiment rig of intake port. The experimental results show：eccentric chamfers have quite little influence on flow coefficient;when normalized valve lift is smaller than 0.184,6,eccentric chamfers can significantly increase swirl ratio,and obvious differences exist among eccentric chamfers of,the concerned cases;when normalized lift exceeds 0.184,6,swirl ratio curves of all the cases almost coincide with each other. 2,mm and 9,mm were selected to be on behalf of small and large valve lift respectively,and 3D numeric simulation of port-valve-cylinder model was performed with the help of computational fluid dynamics（CFD）. The simulation results suggest that at 2,mm lift,compared to the case without eccentric chamfers,in which two swirl structures from different directions appear in the cylinder.Eccentric chamfers are able to prevent impact and interference phenomenon between different air flows,causing a single swirl to form inside the cylinder;as a result,however,one single swirl can always form inside cylinder at 9,mm lift,regardless of eccentric chamfers. Therefore,the experimental results are explained from the point of mechanism.
出处
《天津大学学报（自然科学与工程技术版）》
EI
CSCD
北大核心
2015年第11期974-980,共7页
Journal of Tianjin University：Science and Technology
基金
国家高技术研究发展计划(863计划)资助项目(2014AA041501)
关键词
稳流实验
偏心倒角
数值模拟
撞击干涉
steady flow experiment
eccentric chamfer
numerical simulation
impact and interference
