When the propeller of an aircraft rotates, it produces a pulling force, why does an electric fan pro

Quite simply, if you stand behind an airplane propeller, can't you feel the wind blowing backwards from the airplane propellers? Similarly, if you take a piece of paper and slowly approach it from behind, it will be sucked into the metal frame of the fan. The principle of the two is essentially the same.

The difference between propeller and electric fan blades is that the blades are slender and the other is short and thick. Electric fans also have short rounds, like ship propellers. When the ship's propeller turns, the current accelerates. This is the same effect as an electric fan.

So why does the electric fan pull but not move? The main thing is that the power is not enough. Electric fans use an electric motor that relies on a magnet coil to produce rotation.

The electromagnet is very heavy, the power of the motor of a fan is only a few tens of watts, hundreds of watts, and the ratio of power to weight is very small, and the fan cannot be moved.

In addition, the propeller profile adopts an airfoil with increased lift, which is more efficient than the flat blades of a fan and generates more pulling force.

Both the propeller and the fan create a pulling force and accelerate the air flow to form the wind. Due to the different weight-to-power ratios, one can move, the other does not move. The force generated by the fan is overlooked.

The blades of an electric fan, as long as they turn, generate a reaction force. Have you seen it? The base of the electric fan is very large.

Especially for the trolley fan, the base is all cast iron. The goal is to be steady. The propeller of the aircraft, when it "blows" backwards, has the force of "forward" flight.

In fact, it's all the same, the electric fan is also wind to itself, and it is also a wind to the ground. If the blades are big enough, the fan will also flip back. If you want, put the *** propeller up and turn, it's a giant electric fan. It's really hard to understand.

The principle of action is the same, strong power produces lift or pull, and the direction is different, the gyroplane is this mode, the kinetic energy of the fan is small, and the airflow rate is low, similar to the natural wind.

You can put the fan in the basin, let the basin float on the water, and turn on the fan and you will see the basin move forward. As long as the electric fan can generate a fast enough wind, it can pull the plane into the sky. It's just that the wind from the usual electric fan can't even move the base, so you can't see that it also produces a pulling force.

The use is different, the electric fan wants the wind, and the aircraft propeller wants the pull to pull the plane to fly. To explain this problem clearly, we can make an anatomy from the wing of the airplane, the upper and lower wings of the airplane are different, and the lower wing surface is similar to the plane, so that the air flow is slow when it passes, and it can also be said to be the normal flow rate. The upper surface is convex, that is, it has a curvature, so that the air flow diverges when it passes through and the flow rate is fast.

The air is divided into two streams of air through the wing, the lower airflow is slow and the pressure is strong, the upper airflow diverges, the loss is fast and the pressure is small, and the force is the coexistence of action and reaction force, so that the force of the lower wing surface will be transferred to the upper wing surface, which is the lift.

The air flow caused by the pulling force, when the electric fan rotates, the ability it generates is the wind, and we can't do without the electric fan in summer.

Because the blades of an electric fan are fixed, when they rotate, the blades will squeeze the air, forming a flow of air, so wind will be generated.

They are essentially the same, but when the agent narrates them, one says the force and the other the wind. Therefore, it is important to establish, how does the force come about? How is wind generated?

In fact, the rotation of the blades interacts with the air, and the force they force against each other is the force of the propeller. When the air is pulled apart by the propeller, the wind is created.

1.Electric fan - the propeller and blade look.

I have never seen a propeller, no doubt I have seen an electric fan, no doubt I have seen a Dutch windmill that I played with as a child. Naturally, strictly speaking, there is a very big difference between the Dutch windmill and the previous one (active and passive). However, its leaves look similar.

Each bit is irregularly distorted.

2.Crooked blades – interaction with air.

The indoor space of everyone's daily life is filled with air everywhere. Although you can't see or touch it, the air does exist. Propellers, or electric fans, their blades interact with each other throughout their rotation.

Like our own hands, we can perceive the presence of air when we shake rapidly, and this cognition is actually based on the effect of air on our arms.

Because the crooked blade, when rotated, touches the air above the circle in which it rotates. The rotating blades will push this part of the air forward to promote this part of the air, as shown by the dark blue arrow symbol in the image below. Because the air is liquid, the blade pushes the air around the blade forward, and the air behind it fills, as shown by the red arrow below.

The air is then continuously directed to the right, creating wind. In this link, the blades promote the air, and the air can move forward for fitness. According to Newton's laws, there must be a force.

At this point, you should have already responded to this question. However, you will find a very strange question, why are the propeller blades so different from the appearance of electric fan blades?

3.Blade design scheme.

The actual construction of the cutter head is related to the requirements of the profile. For electric fans, only the suitable exhaust air volume, small speed ratio, and small in-situ stress on the virtual structure of the blades must be considered, and the annular plastic material can be considered for application regulations. However, for the propeller, the speed is relatively high, and the blade must pass rigorous calculation and analysis in order to achieve the application regulations, complete its corresponding role, and ensure the hardness and bending stiffness of the blade itself.

In fact, this analysis is quite complicated, and it is not like a general structure, which is separate from air. The structure of the blades is closely related to air, which involves both solid and liquid ways. Dissecting alone, it should be said that it is very easy.

But when solids and liquids are put together, the dissection becomes more and more complicated. Therefore, companies that can produce and manufacture propellers need to have their own technical capabilities, and they cannot rely on all one person to analyze and succeed (other than counterfeiting).

4.Introduction Whether it is a propeller or an electric fan, in the process of rotation, the blades will interact with the air to create an interactive force, which will promote the air to generate wind.

The actual appearance of the blade is related to the application regulations (design scheme index value), and must be rigorously measured and analyzed to ensure that its function and its own structure are sufficient and firm.

On the plane, the lack of two propellers will produce opposite forces, and there will be a pulling force when running, which will drive the flying delay pure machine to fly, and the electric fan has only one direction, and it is the air that rotates, which will naturally produce wind pulsation.

When the propeller of the aircraft rotates, the envy of the silver pai chang is the tension, because there are two propellers on it, the propeller will produce forces in different directions, and the law of conservation of meridian roots will become tension, and when the electric fan is transmitted, it will become wind in one direction.

The propeller of the aircraft will also produce wind, but the propeller is connected to the engine of the aircraft to bring lift to the aircraft, and the electric fan is just a simple Danhe motor to drive the blades to rotate.

When the propeller of an airplane rotates, it comes into contact with air, which is a fluid that forms wind during the rotation.

Because the propeller of the aircraft is very large, the propeller of the electric fan is too small to produce tension, but a relatively large propeller can produce tension.

What an electric fan needs to blow during operation. The airplane relies on the propeller to drive the air, and then pulls the plane forward, and the propeller speed is very fast.

1.Electric fan – the shape of the propeller and blades.

I've never seen a propeller, I've definitely seen an electric fan, I've definitely seen a windmill I played with when I was a kid. Of course, strictly speaking, there is a big difference between a windmill and the former (active and passive). However, its blade shape is similar. Each blade is irregularly twisted.

2.Twisted blades – interaction with air.

Due to the twisted blades, when rotated, they come into contact with air in the circumferential direction of their rotation. The rotating blades push this part of the air forward to push this part of the air, as shown by the blue arrows in the image below. Since the air is fluid, the blades push the air near the blades forward, and the air behind them is replenished, as shown by the red arrows in the figure below.

Then, the air will be constantly pushed to the right, forming a wind. In this process, the blades push the air, which can move forward. According to Newton's theorem, there must be a force.

3.Blade design.

In fact, this analysis is quite complex, unlike the general structure, which is independent of the air. The blade structure is closely related to air, which involves both solid and fluid forms. Single analysis, it should be said that it is relatively easy.

But when solids and fluids are together, the analysis becomes more complex. Therefore, enterprises that can produce propellers must have their own technical reserves, and cannot rely on any one person to analyze the success (except for copycats).

4.AbstractWhether it is a propeller or an electric fan, during the rotation, the blades will interact with the air to create a force that pushes the air to form a wind.

The specific shape of the blade is related to the requirements of use (design indicators), which requires rigorous calculations and analysis to ensure that its function and structure are sufficiently strong.

Because the magnitude of this force is different. When this force is strong enough, it becomes a pulling force. The power of the electric fan is relatively small, so it will also generate wind, and if the power is relatively large, it will also produce pulling force.

Because the magnitude of this force is different. You can understand it this way, when this force is strong enough, it becomes a pulling force. The force generated when an electric fan rotates is very small, so it can only be one type of wind.

Because the direction of the fan blades is different when it rotates, the direction of the wind generated when the fan blades rotate will also be different.

Because the force generated by the electric fan when it rotates is very limited, there is no way to drive its own displacement, while the force generated by the propeller of the aircraft is very large, which allows them to fly on their own.

Because when the electric fan rotates, it does not produce a rising lift force with the material in the air, and when the propeller of the aircraft rotates, it is affected by the wind in the air and produces a rising lift force.

The pull is not enough. The blades of the electric fan are small, and they are all plastic, the mass is too light, and the pulling force generated is too small to lift off like an airplane.

Pulling drawers is a translational phenomenon; The rotation of the spiral propeller of the aircraft and the electric fan at work belong to the rotation phenomenon;

Therefore, the answer is the brother sedan chair: b; a，c．