Hainanquwei gave a good answer on the eighth floor. Generally, if it is new, it will be numbered during installation. If the old and new blade are installed together, weigh the blades to see if they are the same. adjustment is generally made at the top of the blades. Simply use a universal angle ruler and a steel plate ruler to measure to 20mm. The general angle is 9 to 11 degrees. One more point: In addition to the above factors, the fan blade angle should also consider the process requirements and motor current. The second question asked by the original poster: Adjusting the gap between the fan blades and the air duct? The general requirement is not less than 10mm, but it should not be too large to affect the air volume.
Principle of the fan however, in order to have a certain solidity, the closer the fan blade is to the root, the more itbecomes thick. Made of fiberglass. The fiberglass reinforcing ribs are placed in the mold and then injected with resin to form. The small air leaf has a solid structure and the large one has a hollow structure. The hollow part of the large fan blade is almost half the size of a cylinder. It is no exaggeration to say that it is based on the principle of a sail. The installation angle of fan blades is generally adjustable. The wind turbine has a complete constant speed device and a device that automatically brakes, then turns and finally turns again when the wind direction changes. Don't do your own research and development. If you want to make a finished product to sell, simply buy one and then reverse engineer it. You can search for “fiberglass fan blade manufacturing process”.