汽油机进气过程缸内气流及边界层流动特性  

In-Cylinder Flow and Boundary Layer in Gasoline Engines During Induction Process

作　　者：刘大明[1] 李卫 王天友[3] 田福全 甄旭东[1] Liu Daming;Li Wei;Wang Tianyou;Tian Fuquan;Zhen Xudong(School of Automobile and Transportation,Tianjin University of Technology and Education,Tianjin 300222,China;Engine R&D Center,Weichai Power Company Limited,Weifang 261061,China;State Key Laboratory of Engines,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津职业技术师范大学汽车与交通学院,天津300222 [2]潍柴动力股份有限公司发动机研究院,山东潍坊261061 [3]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》2021年第3期241-249,共9页Transactions of Csice

基　　金：国家自然科学基金资助项目(51706155);国家杰出青年科学基金资助项目(51525603);天津市教委科研计划资助项目(2017KJ114);天津职业技术师范大学人才启动资助项目(KYQD14050).

摘　　要：将改进的延迟分离涡模型(IDDES)应用于汽油机进气过程缸内气流运动的数值模拟,通过壁模型的改进提高了对内燃机近壁流动模拟的可靠性.模拟结果得到了近壁显微粒子图像测速技术(micro-PIV)试验数据的验证,在此基础上,研究了进气射流影响区域近壁量纲为1的速度分布,分析了缸内不同尺度分流场的能量分布和近壁区域瞬时流场的准周期波动.研究发现:高升程、高气道压差工况拟序流场占能比例仅有11%,而低升程、低压差工况可达到37%,拟序流场占能比例的增加使流场变动显著增大.进气射流存在明显的摆动现象,进气射流区域的拟序流场中可以观察到明显的旋涡结构,且旋转方向呈现准周期性翻转.对于近壁流动,受进气射流波动影响,区域内边界层量纲为1的速度分布在对数区过早地向下弯曲,偏离对数分布,与稳态槽道流动边界层有较大的差异.The improved delayed-DES(IDDES)model was applied to numerically simulate the in-cylinder flow of a gasoline engine during the induction process.The improvement of the wall model enhanced the reliability of the near-wall flow simulation.The simulation results were verified by micro-PIV experimental data for the near-wall flow.The dimensionless velocity distribution near the wall in the area affected by the intake jet was studied.The energy distribution of the flow fields of different scales in the cylinder and the quasi-periodic fluctuation of the instantaneous flow field near the wall were analyzed.Results show that the energy in the coherent flow field accounts for only 11%in the conditions of high valve lift and high port pressure drop,while it could reach 37%in the conditions of low valve lift and low port pressure drop conditions,which causes a significant flow field fluctuation.In addition,the intake jet swings significantly.Obvious vortex structure can be observed in the coherent flow field of the intake jet region,and the direction of rotation presents a quasi-periodic reversal.For near-wall flow,due to the influence of intake jet fluctuations,the dimensionless velocity distribution of the boundary layer in the logarithmic region bends down prematurely,deviating from the logarithmic distribution,which significantly different from the boundary layer of the steady-state channel flow.

关 键 词：汽油机 近壁流动 进气射流 本征正交分解 

分 类 号：TK411[动力工程及工程热物理—动力机械及工程]