Mask对四气门汽油机滚流影响的三维模拟分析

采用CFD三维模拟研究了带有气流阻挡结构Mask的高滚流气道的滚流比和流量系数,着重讨论了Mask及改变Mask宽度及高度对进气参数的影响。对无Mask及Mask宽度分别为0.2mm,0.5mm和1mm的8种高滚流气道的流通性能进行了稳态模拟,AVL平均滚流比为3.0~3.5,AVL平均流量系数在0.25~0.30之间。此外还模拟分析了Mask高度分别为1,2,3,4,5mm的气道。结果表明:增加Mask后,小气门升程时滚流强度显著增大,大气门升程时滚流比略微减小;Mask宽度越小、高度越大时,在小气门升程时滚流强度越大;Mask高度由1mm增加到5mm时,AVL平均滚流比增加了6.4%,平均流量系数减小了11.4%。

Effects of Mask on Tumble of 4-Valve Gasoline Engine Based on 3D Simulation

The tumble ratio and discharge coefficient of high tumble ratio intake ports with Mask airflow blocking structure were simulated by CFD three-dimensional simulation and the effects of Mask and its width and height on tumble ratio were emphatically discussed.The steady simulation of flow characteristics was conducted on eight high tumble intake ports without Mast and with Mask of 0.2 mm,0.5 mm and 1 mm width.AVL average tumble ratio was 3.0-3.5 and AVL average discharge coefficient was 0.25-0.30.Then the intake port with Mask of 1 mm,2 mm,3 mm,4 mm and 5 mm height were simulated and analyzed respectively.The results show that the tumble intensity increases significantly at small valve lift and the tumble ratio decreases slightly at large valve lift after using Mask.The larger tumble ratio produces at small valve lift when the smaller width and the larger height of Mask are used.AVL average tumble ratio increases by 6.4% and AVL average discharge coefficient decreases by 11.4% when the Mask height increases from 1 mm to 5 mm.