基于CFD双通道涡流室式柴油机缸内气体流动模拟研究

Numerical Simulation Study on Air Flow in the Cylinder of a Diesel Engine with the Dual Channel Swirl Chamber Based on the CFD

以BH175F1柴油机涡流室系统为研究对象,将镶块单通道改进为双通道结构,考虑启动孔,基于计算流体力学技术(Computational Fluid Dynamics,CFD)对单通道涡流室系统和双通道涡流系统从进气门关闭时刻到上止点时刻缸内气体流场特性进行数值模拟,得到单通道与双通道涡流室系统缸内速度矢量图和压力云图。研究表明:随着曲轴转角从588°CA到720°CA,气体逐渐被挤压进涡流室,单通道涡流室与双通道涡流室内形成相似涡流,单通道涡流室内平均气体流速较大,双通道涡流室内涡流流速分布较为均匀。初期缸内压力大于涡流室内压力,涡流室内逐渐形成涡流,涡核区域压力最低,近壁面区域压力较高,其中涡流室内气流运动拐角处压力最大,单通道涡流室内压力最大达到4.43MPa,双通道涡流室内压力最大达到4.42MP。

Taking the BH175 F1 diesel swirl chamber system as the research object,which improves the single channel of insert block into a dual-channel geometry,in consideration of booting up the hole,Computational Fluid Dynamics(CFD) is used to simulate the characteristics of the gas flow field in the single-channel swirl chamber system and dual-channel swirl flow system from the closing time of the intake valve to the top dead center,the single-channel and dual-channel swirl chamber system cylinder velocity vector and pressure cloud mapsare gained.The result indicates that,as the crank angle increases from 588°CA to 720°CA,the flow velocity of the single channel swirl chamber diesel Engine is slightly larger in eddy current indoor,and the single-channel swirl chamber diesel Engine forms similar eddy current with the dual-channel swirl chamber diesel Engine indoor.the flow velocity of the dual-channel swirl chamber diesel Engine indoor vortexes is distributed evenly.At first,the pressure in the cylinder is greater than the eddy current indoor,and indoor gradually forms vortexes,and the pressure is the lowest in vortex core region,and the pressure is higher in swirl chamber near wall area,of which is the highest in eddy current indoor airflow movement around the corner.The maximum vortex pressure in the single channel swirl chamber diesel Engine reaches 4.43 MPa,while 4.42 Mpa for the dual one.