The number of blades "24V DC Cooling Fan": a variety of fan blade section curve, dip and other basic similar, each blade width often depends on the height blades. In order to ensure the blade pitch will not be too large, the impact of wind pressure, high diameter is relatively small (ie, relatively thin) fan blades increase the number of multi-use method to compensate. Regardless of the number of blades are mostly small, the number of blade axial "24V DC Cooling Fan" has often 3,7,11 and so odd, which is due to the use of a symmetrical shape even-piece blades, but did not adjust the balance, it is easy to make the system resonance, if the blade material is unable to resist vibration fatigue, will make the blades or spindle breakage, so much about design as "24V DC Cooling Fan" axis of asymmetry odd piece blade design. This principle is widely used in a variety of designs including some helicopter propeller blades, including in.