Abstract:

An optical variable tumble intake port steady flow rig for 4-valve GDI engine was established, and a PIV system was used to study the change of in-cylinder airflow under different intake-valve lifts at two cases of opening and closing the tumble control valve(TCV). Results show that: in-cylinder swirl motion at both of two cases is mainly tumble motion which flows around the axis perpendicular to the cylinder axis. When TVC is open, two large scale tumbles, a counterclockwise and a clockwise, respectively emerge on the left and right sides in the cylinder. When TVC is closed, the airflow velocity under the intake valve side in the cylinder becomes weak, while the airflow under the exhaust valve side is greatly enhanced, a single clockwise tumble flow trends become apparent. When intake valve lift is smaller, the effect of tumble change with TCV is very weak.

Key words: 4-valve GDI engine, variable tumble intake port, tumble, particle image velocimetry(PIV)

摘要：

建立了可变滚流四气门直喷汽油机光学可视化气道实验台，利用粒子图像测速（PIV）系统对不同进气门开度、不同滚流调节阀工作状态下的缸内气流运动规律进行了实验测试研究。实验结果表明，缸内主要是绕气缸轴线垂直方向旋转的滚流运动;滚流阀开启时，缸内左右两侧分别形成逆时针和顺时针方向的两个大尺度滚流;滚流阀关闭时，进气门侧的气流减弱，排气门侧的流速明显增强，缸内出现了较强的单一顺时针方向滚流运动趋势;进气门开度较小时，改变滚流阀状态对缸内进气流动的影响很微弱。
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关键词: 四气门直喷汽油机, 可变滚流进气道, 滚流, 粒子图像测速