吊扇叶尖改进的新途径

吊扇的设计方法是以旋翼空气动力学的二维流动模型为基础,这对吊扇叶身部分比较吻合。然而占扇叶长度约10％的叶尖区域却处在强烈的三维流动状态下,用四氯化钛所作的吊扇流场显示实验可清楚观察到。如图1所示,叶尖部分有清晰的径向流动,叶尖线速度越大,叶尖区域气流径向流动速度也越高,紧靠叶尖

A NEW APPROACH TO IMPROVEMENT OF FANS

This paper presents experimental results of 3-D flowfields in the fan tip region for two actual fans. It is shown that the fan performance can be significantly improved as proplets are attached to the blade tips. The improving mechanism have been studied and can be stated as follows: The proplets retain the tip vortex and thus the tip induced loss is reduced remarkably, and the additional propulsion moment is gained because the proplets partly balance the drag moment due to profile loss in the tip section. The conclusions presented in this paper may be applied to the tip section of propeller or helicopter rotor for performance improvement.