4气门汽油机气道滚流比测试方法的试验研究

摘要

对汽油机缸内滚流直接测量方法的测试装置进行了可视化处理,在自主开发的气道稳流试验台上,通过PIV技术研究稳态滚流测试过程中流场的微观结构及其演化规律,阐明不同模拟缸套结构参数对气道滚流比影响规律.结果表明,不同结构参数的模拟缸套内流场结构在气门升程达到一定范围时都会发生变化,形成大尺度逆时针滚流,并且会导致缸内各测量截面滚流比曲线斜率增大.而缸内流场不同区域受缸套形状影响程度不同,出气口附近截面内滚流比受其影响最大,对于出气口直径为0.35倍缸径的模拟缸套,出口附近截面内滚流比出现非常高增幅的跃升,跃升后滚流比达到3.08.气道稳流试验模拟缸套内滚流比的变化规律从根本上受角动量守恒支配,缸套形状与滚流比产生增幅过高的跃升存在本质的联系.%An investigation on characteristics of in-cylinder tumble flow in a four-valve gasoline engine is presented.The experiments were carried out on an in-house steady flow test rig by combining optical accesses and visualization devices for directly exploring in-cylinder air motion.PIV was employed to evaluate the effects of various geometry parameters on flow field and microstructures.Results show that largescale counterclockwise tumble flows is formed and the slope of tumble ratio curve increases when the valve has adequate opening.The in-cylinder flow field is very sensitive to the in-cylinder geometry in different in-cylinder position,particularly in area near the blow hole where tumble ratio increases up to 3.08 with the blow hole diameter of 0.35,D（D is the cylinder bore）.The study suggests that the evolution of incylinder tumble flow is basically dominated by the conservation of angular momentum,while the change of in-cylinder geometry results in some difference on tumble ratio.