Select 24V DC Cooling Fan number of leaves

In the future, with the development of technology, three of the "24V DC Cooling Fan" will still exist, but there will be great changes in materials and design as the blades are also using new materials. Increase the blade angle greater wind and the like. Leaf number of options:
1, "24V DC Cooling Fan" technical aspects: the number of leaves too much can make the chord length shorter blade curvature becomes large, adverse pressure gradient increases, the air easily separated, leading to a decline in efficiency. Thus, to increase the number of leaves by minimum blade chord length limit.
2, the production cost considerations, three fan blades more economical.
3, from the exterior to consider: 3 blade fan than 2, 4 a little more beautiful.
4, mechanics point of view: 3 fan can form a reasonable mechanical power asymmetry can save power and save energy.
4, "24V DC Cooling Fan" After a long optimization iteration, taking the best leaf number three.