This question is complex. The current dominant technology is vacuum resin transfer technology, where each component is prepared separately, and then the high pressure and low pressure tablets are molded together to form a whole. The details would take thousands of words. Vestas, LM, GE, Goldwind, Sany, AVIC Huiteng, etc. all use this technology. Siemens has integrated molding technology, that is, the high pressure sheet and the low pressure sheet are molded together, thereby reducing the mold clamping process. Some blades, of relatively regular shape, are also formed by the winding method. Japan is also developing a thermoplastic blade that joins fibrous materials and solid resin, heats the resin in the mold clamp and shapes it after cooling.
The original rear (inward) side of your fan is the windward side. It is recommended to useer a three-blade fan with a diameter of approximately 1.5 meters. Are they basically fans like that? The shape of the fan blade used for blowing is different from the shape of the fan blade. It should be a leaf shape similar to the wings of an airplane.