The electric fan does not need a pulling force, but a blowing force. If the blades of an electric fan are shaped like the blades of a propeller plane, they will deviate from their path and reduce airflow. The electric fan blades do not need to take into account the different shapes on the two sides of the blades. They just need to solve the problem of the twist angle of the blades, so that the air volume is large. Therefore, the production of electric fan blades is relatively simple. It is not necessary to have different structures on both sides, just use a piece of iron or a piece of plastic. Planar propellers are not permitted. The front and rear blades should have different structures, with one side almost flat and one side curved.
The goal is also different. The electric fan is the wind, and the propeller of the plane is the force ofe traction, which involves pulling the plane so that it flies. To illustrate this problem, we can make an anatomical diagram of an airplane wing. The top and bottom of the wing are different. The bottom of the wing is flat, so air passes through it very slowly, or at normal speed. . The upper surface of the wing is convex, that is, it has an arc so that the airflow passing through it is diffuse and rapid.
The cross-sectional shape of the propeller blade is similar to that of the wing. The front aerofoil has a greater curvature and the rear aerofoil is flatter. The leading edge of each blade is consistent with the direction of rotation. of the engine output shaft, which is equivalent to The wing is blown by the air flow and the propeller blades have a twist angle. This twist angle (blade angle) is equivalent to the angle of attack of the aircraft wing. Therefore, a propeller plane does not rely on the air blown by the propeller to propel the plane, but when flying it does not depend on the air blown by the propeller. air blown by the propeller to propel the aircraft, but when flying, the propeller blades can also produce backward blown air, which may have the power to drive air flow theory air of the plane's flight.
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Is the wind blown by the Mingtao electric fan very cool?
You can do an experiment, take 2 paper pinwheels and place them one behind the other in front of the fan, see if the latter is still goingrner.
Once the wind turns a generator to produce electricity, the wind energy is converted to kinetic energy and the wind energy is reduced. If there is a generator directly behind it, the wind energy received will be reduced.
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Additional information:
1. As the poster says, if installed in a pipe, the windmill on the back will naturally rotate, because when the wind blows from one end, it will inevitably blow from the other end, because the pipe changes the wind direction, forcing the wind direction disturbed by the windmill to return to its original direction. But wind turbines are built in nature and the wind flows freely without a pipe to hold it. The wind blows from one direction and passes in front of the wind turbine. The direction has been disrupted and the speed has been reduced.
2. I don't really understand this questiontion.
The wind turbine rotates slowly because the wind speed at that time is slow. The faster the wind speed, the faster the rotation speed. The wind does not only blow between the blades, because the direction of the blades is not parallel to the direction of the wind, but at a certain angle. The wind blows on the blades, causing them to spin. During this process, the wind works on the blades and the kinetic energy of the wind is converted into the kinetic energy of the generator.
Let's take an extreme example: when the wind blows on a wall, the wall does not fall, the wind speed drops to zero and the wall receives an external force. If the wall collapses, the wind speed will not be zero, but the speed will slow as work is being done on the wall – the same principle as a generator.
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2 additional:
1. As the poster says, the air entering the duct is teaorically continuous. wind enters a uniform duct (same duct cross-section) and the instantaneous velocity leaving the duct must be the same because there is no loss of air volume. This should get all the fans going.
The condition we assume here is a cylindrical pipe with the same cross section. Since the wind direction remains unchanged, we have come to the above conclusion. The original poster previously assumed a small box with two opposing holes. If it's a square box (the kind with edges), it's hard to tell whether to open two holes on each opposite side. Since gas swirls will occur in the corners of the square box, we also need to consider various changes in the gas inside the box. . . Very complicated. If you are interested, I suggest you read some books on fluid mechanics.
2. When the blades of thefan are stationary, the gap between them is indeed large; but once the fan blades rotate, the gap between them will become smaller. For example, when an electric fan is running, can you see the spaces between its blades? ----can't. But when you turn off the switch, the fan blades spin slower and slower and the gaps become more and more obvious.
So when the wind turbine blades are stationary or slowly rotating, there will be breeze or air passing between the blades; when the wind speed increases and the blades spin faster and faster, there will be no wind. gaps.
We bought one from us, and we think its features are: cheap price, strong wind and the wind range is okay, especially the motor is powerful, and it doesn't make hot even after blowing. for a whole day. As for his longevity, , still used.
It is difficult for me to understand what LZ calls fresh wind. The principle of an electric fan is basically the same. It is a source of wind that drives the blades to accelerate the airflow. There is no air conditioning in summer, but it is not expensive to cool down.