"220V AC Cooling Fan" performance by many parameters, such as the stacking height, blade curvature, leaf inclination, blade pitch, blade thickness, number of blades, blade angle of attack, the leaves end clearance, blade width, spindle diameter, etc., and mutual constraints among parameters, complex relationship. Constantly adjust the parameters to find the most suitable combination of objective job requirements, fan design is carried out by researchers working on. To these "220V AC Cooling Fan" parameter fully explained and analyzed, enough to write several doctoral thesis, but this is just superficial to analyze air-cooled heat sink technologies, in fact not be necessary, I have no this ability -_-. Therefore, only a few users are more concerned about the parameters slightly description: blade curvature: within a certain range, the greater the curvature of the blade, at the same speed, the greater the gas kinetic energy that "220V AC Cooling Fan" air volume and pressure the larger; Meanwhile, the greater the drag blade, require a larger motor torque. When the ratio is high arc / chord length of more than 0.1, it is no longer lift coefficient increases linearly, the "range" that 0.05 <arc height / chord length <0.1.