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4气门汽油机是车用汽油机主要的发展方向,其缸内空气运动的主要形式是滚流,与传统2气门发动机缸内的涡流运动不同。本文用LDA在一台单缸4气门汽油机上测量了缸内滚流运动,并借助于多维数值模拟计算分析了滚流的形成和演变規律,研究了规律的湍流特征。研究指出,滚流形成于压缩过程初期,以后随活塞运动得以维持和发展,它在压缩末期衰减、畸变和破碎,使燃烧室内湍流强度显著增加。
The 4-valve gasoline engine is the main development direction of the gasoline engine. The main form of air movement in the cylinder is tumble flow, which is different from the vortex motion in the conventional 2-valve engine cylinder. In this paper, LDA was used to measure the tumble motion in a single-cylinder 4-valve gasoline engine, and the formation and evolution of tumble flow were analyzed by multi-dimensional numerical simulation. The regular turbulence characteristics were also studied. The research shows that the tumble flow is formed at the initial stage of compression process and then maintained and developed with the piston movement. It decays, distorts and fractures at the end of compression, resulting in a significant increase of turbulence intensity in the combustion chamber.