1, "220V Cooling Fan" several blades. It leaves theoretically possible, to maximize contact with the blade drive air. But the reality is clearly not too dense, then each blade between the flow field would interfere with each other, superimposed on the actual words do not come out, 3D printing is applied, it can greatly change the existing design ideas. If too thin, and low efficiency.
2. "220V Cooling Fan" cross-sectional shape of the blade. Because the aircraft design and manufacture of the historic, investment, industry development, there are a huge number of aerodynamic data, it is now widely used in aircraft airfoil blade airfoil, what Goettingen airfoil, LS airfoil, NACA series, high lift wing type and so on, each wing has its own temper, scope of application. Household fans, industrial fans there is no such problem, straight, turn up a piece of iron on the line.
3. "220V Cooling Fan" installation angle (tilt angle of the blade). Popular to say, it is how to maximize the wind into an axial flow fan rotation problems. You can see the drawing fan, the inclination of the blade root and the maximum outer diameter is different, that is the inclination angle of each radii are different.