It's because the media they push are different. Air and water are thin and heavy, and their resistances are completely different. Additionally, the ship floats directly on water, while the plane must fly in the air. If the airplane propeller is used on a ship, even if the engine can start, its blades will break immediately due to too much resistance. If a ship propeller is used on an airplane, the airplane will not be able to take; no matter how fast it goes.
The definition of pitch: the distance traveled by the propeller in the axial direction during one revolution. The propeller is responsible for converting engine power into forward thrust. Its importance goes without saying. The principle of the propeller powering an aircraft is similar to that of rockets, steering fan aircraft, and jet aircraft.
The propeller is responsible for converting engine power into forward thrust. Its importancest obvious. The principle of propelling an aircraft with a propeller is different from that of rockets, fan-guided aircraft and jet aircraft. and is also different from marine propellers. Rockets move forward due to conservation of momentum. If a plane also moves forward based on the principle of conservation of momentum, then the propeller must blow as much air as possible backwards as quickly as possible. the propeller shape should be as wide and short as a fan blade. They are not long and thin like we see now. The shape of the fan guide blades is similar to that of a marine propeller, but the efficiency is very poor because. the guide fan motor, acceleration tube and bracket block a large part of the airflow, and the air returned by the guide fan The speed is not fast enough and the quality is not sufficient.
The most important thing is thewind efficiency ratio. The large blade reduction improves the wind efficiency ratio. Because the wind is blocked, the wind passing through the windmill will slow down, even slowing to 1/2 or 1/3 of its original size. Following explanation 1 above, the windmill will slow down because the blades are too big. to push the generator quickly. Explained from an energy point of view: the wind is blocked and escapes from the windmill, so the wind energy is not captured by the windmill. Hydroelectric generators have large blades, provided that the diameter of the blades and pipes are the same so that the energy of the water flow cannot escape. But the blades can't be too big, otherwise it won't work if they block the flow of water and don't drain the flood. Additionally, the water flow is basically blocked, the turbine cannot rotate, and the turbine cannot produce electricity. The differenceThe essential difference between an electric fan and a wind turbine is that the electric fan is actively driven and the side wind leakage is several times smaller.
And the speed is very high and stable. The higher the speed, the wind speed that the windmill faces cannot be as high and stable.