Micro Cooling Fan blade tip clearance

How to adjust the "Micro Cooling Fan" gap exists between the fan and the fan frame design is a major problem. Here the gap is too small will make the airflow and the blade, frame friction, noise increases; the gap is due to the increased air flow and other effects flyback ear reduce fan efficiency - the gap increases by 1%, the total pressure drop of about 2% power . Blade spacing: the distance between the blades is too small, will result in flow disturbances, increasing the friction surface of the blade, reducing the efficiency of the fan; the distance between the blades is too large, it will lead to increase in pressure loss, lack of air pressure. Spindle diameter: Due to the motor and bearings, the central part of the axial flow "Micro Cooling Fan" Spindle where certain non-blind inevitably flow through the spindle diameter will determine the size of this blind spot. Spindle diameter size depends mainly on the power of the fan motor - powerful motor stator winding need more, must take up more space, without being able to scale up (increasing the height), it would have to scale (increasing the area). Although the "Micro Cooling Fan" of the blade section from the same base curve and more, can make various adjustments also are limited within a certain range, but there are some manufacturers have made great improvements made very distinctive design.