羽形风扇的叶片上开有V型锯齿,可以打断由光滑叶片边缘引起的涡流(风扇外型见图1)。由叶片产生的涡流所引起的振动声音,不是集中在狭窄的高频带里。要达到最佳的低噪声效果,应使每个叶片的锯齿有同样的尺寸和间距,但开端和末尾的锯齿在沿叶片的边缘上稍有不同。这错开的设计是 The feather-shaped fan has V-shaped serrations on the blades that interrupt the eddy currents caused by the edges of the smooth blades (see Figure 1 for fan appearance). Vibrations caused by eddy currents generated by the blades are not concentrated in the narrow high frequency band. To achieve the best low-noise results, the serrations of each blade should be the same size and spacing, but the beginning and end serrations are slightly different along the edge of the blade. This is a staggered design