"Micro Cooling Fan" leaf number and spacing of the blades have opposing relationship, the more the number of blades, blade pitch to be reduced, so that the increase in the number of blades to remain narrow, in addition to increased friction, the influence of interference is more obvious each blade ??? So the turbulence will also rise, while the spacing between them will affect the blade noise "Micro Cooling Fan" of aerodynamics and fan generated by the blade pitch is too small, it increases the chance of friction surface of the blade, causing the fan efficiency reduced relative blade spacing is too large, the separation phenomenon is a pressure loss becomes large. There are many on the market to buy a lot of very cheap cooling fan, the appearance looks no difference with the Secretary selling cooling fan, but when we open look inside the structure is really not the same, not a lack of this part is the lack of it parts, we again do the experiment, "Micro Cooling Fan" is operated, broken a few days, so a few days to buy back the product useless broken, in terms of human and material resources, is a loss.