气门形状对汽油机缸内空气运动的影响

内燃机缸内的空气运动对混合气的形成以及燃烧过程有着重大影响,是燃油消耗率,排放和燃烧噪音的决定性因素之一.多维数值模拟方法具有费用低,给出的信息量大等特点,便于研究几何形状等参数变化对内燃机燃烧性能的影响以及进行多方案的对比研究.将其用于内燃机缸内流动过程的研究,可对内燃机缸内流运过程的研究提供一种新的研究手段.本文用任意拉格朗日-欧拉法(ALE方法)编制的大型KIVA3程序模拟了某四气门汽油机的缸内三维流动过程;研究了两种不同长度气门杆的四气门汽油机的缸内流动,分析了汽油机的进气门形状对缸内空气运动及缸内滚流的影响,研究结果表明,四气门汽油机的使用,能在缸内产生滚流现象,气门形状不同,缸内滚流的大小略有不同,采用长气门杆,其缸内滚流要比短气门杆略强一些,这些研究结果可为汽油机的进气道及其气门的设计提供了依据.

Affection of Valve Shape on Air Flow of S.I. Engine

Air motion inside the cylinder of engine plays an important role in the processes of fuel spray and combustion, determine the economy, power output, exhaust emissions and combustion noise of the engine. The multidimensional simulation of the flow in cylinder can give the flow field information in detail and economically, show the effects of geometric and flow parameters to the combustion character, compare the combustion effect of different schemes, provide a effect research methods in engine development. It was simulated of air motion in a 4\|valve S.I. engine in this thesis, the code used was a the KIVA3 code and the code was compiled by ALE method. Air motion inside the cylinder of 4\|valve S.I. engine with two different length valve, and the affection of valve shape on the air flow and tumble flow strength in cylinder was analyzed. The calculated results indicates, the tumble flow was produced by the use of 4\|valve S.I. engine, the tumble flow will be different with different shape valve, and the tumble flow strength with long valve will be stronger than that of short valve. These research results can provide some useful information for the design of S.I. engine.