When the arrow on a weather vanepoints west, the wind is blowing from the west.
Explanation: Under the influence of wind, the wind vane rotates around the vertical axis, causing the wind tail to swing downwind and the head to point in the direction of the wind. So the title says "the arrow of the wind vane points east", and the head points to the direction of the wind, so "when the arrow of the wind vane points east, the wind is blowing from the west".
Basic principle:
When the direction of the wind reaches a certain angle with the wind vane, the wind exerts pressure on the wind vane. This force can be decomposed into two wind forces parallel and perpendicular to the wind vane. . Since the wind-receiving area of the wind vane head is relatively small and the wind-receiving area of the tail is relatively large, the wind pressure felt is not equal. The wind pressure perpendicular to the tail produces a wind pressure moment, causing the wind vane to rotate around the vertical axis until the wind vane head is facing the wind. When the direction of the wind vane is coming, because the forces on both sides of the wing plate are balanced, the wind vane is stable in a certain direction.
The arrow of the weathervane always points to the source of the wind. The principle is actually very simple: the wind-receiving area of the arrow tail is larger than the arrowhead. If both the arrowhead and the arrow tail are subject to wind, the arrow tail will be pushed back by the wind, causing The arrow moves to the source of the wind.
What are the functions of the stator and rotor of the generator? What are they made of? What are the components?
Wind power and photovoltaics are new energy sources that China is focusing on developing. The power grid must fully absorb them and give priority to their use. Hydropower also requires priority use of the power grid during flood periods. This is a comprehensive consideration of a series of factors such as environmental protection and carbon emission reduction by the state. So there is nothing the power grid can do! Why is it called "junk electricity"? There are mainly two aspects.
First, photovoltaic and wind power have small installed capacity and are scattered, making it difficult to meet the peak load regulation needs of the power grid! To put it simply, when the weather is sunny and the wind blows, the insufficient thermal power will be supplemented. When the short-term demand for electricity increases rapidly, photovoltaic and wind power cannot satisfy it. On cloudy days and when there is no wind, the power plant is dead. When there is a power shortage, thermal power is used! And the price of new energy on-grid electricity is relatively high! This means that when the sun comes up, the thermal power load is reduced, and when the sun goes down, the thermal power load is increased. For the power grid, constant adjustments are required, which is not conducive to the security and economic operation of the power grid. Second, wind power and photovoltaics are not stable enough, causing harmonics to be transmitted back to the power grid system, which will increase power losses and affect motor efficiency, which will affect high-precision manufacturing! These two reasons should be the reason why photovoltaic and wind power are called "garbage power".
Both are new energy power generation, which are currently encouraged and vigorously developed by the state, and there are huge state subsidies. , the grid settlement price of thermal power is about 0.3 yuan per kilowatt hour, and the price of wind power and photovoltaic power generation ranges from 0.3 to 0.8 yuan.
Both types of power generation had a fatal flaw at the time, which was their intermittency. Solar power generated electricity during the day and could not generate electricity at night. Wind power could generate electricity when there was wind, but could not generate electricity when there was no wind. These two types of power generation are actually not welcomed by the power grid, but due to the state's support for new energy and the requirements for energy conservation and emission reduction, the power grid company must accept it unconditionally.
There are more and more of these two types of power generation, which bring instability to the power grid. At present, we mainly rely on thermal power peak shaving, pumped water energy storage, wind power heating, and the construction of energy storage power stations to solve intermittent problems. At the same time, wind and solar power forecasts are becoming more and more accurate, which also reduces the pressure on power grid regulation.
Why are wind turbines so far apart?
The stator is the stationary part of the motor or generator. The stator consists of three parts: stator core, stator winding and frame. The main function of the stator is to generate a rotating magnetic field, while the main function of the rotor is to be cut by magnetic lines in the rotating magnetic field to generate (output) current.
The rotor refers to the rotating body supported by bearings. An object that does not have its own axis of rotation, such as an optical disc, can be considered a rotor when it is rigidly connected or has an additional axis. The rotor of the motor is generally composed of an iron core wound with coils, slip rings, fan blades, etc. Main components that rotate at high speed in power machinery or working machinery such as electric motors, generators, gas turbines and turbine compressors.
Extended information:
The generator is mainly composed of stator, rotor, end cover, brush, base and bearings. The stator consists of a machine base, stator core, wire wrap windings, and other structural parts that fix these parts. The rotor consists of the rotor core, rotor magnetic poles (with magnetic yoke and magnetic pole windings), slip rings (also known as copper rings, collector rings), fans and rotating shafts.
The stator and rotor of the generator are connected and assembled through the bearing, base and end cover, so that the rotor can rotate in the stator. A certain excitation current is passed through the slip ring, so that the rotor becomes a rotating magnetic field. The stator coil moves to cut the magnetic lines of force, thereby generating an induced electric potential, which is drawn out through the terminals and connected in the circuit to generate current.
Because there is a break in the connection between the brush and the rotor, the rotor rotates in a certain direction and generates alternating current. Therefore, there is alternating current in household circuits and other circuits, referred to as alternating current. The frequency of China's power grid output current is 50 Hz.
2. Rotor classification:
Typical rotors include turbine machinery rotors, motor rotors, various pump rotors and turbine compressor rotors, etc. When the rotor rotates at certain specific speeds, it will undergo great deformation and cause resonance. The speed when causing resonance is called the critical speed of the rotor.
In engineering, a rotor whose operating speed is lower than the first-order critical speed is called a rigid rotor, and a rotor whose operating speed is greater than the first-order critical speed is called a flexible rotor.
Since the rotor rotates at high speed, it needs to be balanced. Static balancing is mainly used to balance the inertial force of the disc rotor. The dynamic balancing of rigid rotors can use a universal balancing machine to balance the inertial force and inertial couple to eliminate the vibration of the rotor on the elastic support.
The dynamic balance of flexible rotors is relatively complex.Theoretically, there are two types: vibration balance method and influence coefficient method.
Baidu Encyclopedia - Stator
Baidu Encyclopedia - Rotor
You can do an experiment, take 2 paper windmills, one behind the other Place it in front of the fan and see if the one at the back will spin.
After the wind rotates a generator to generate electricity, the wind energy is converted into kinetic energy, and the wind energy is reduced. If there is a generator immediately behind it, the wind energy received will be reduced.
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Supplementary information:
1. As the poster said, if it is installed in a pipe, the windmill at the back will naturally rotate, because When the wind blows in from one end, it will inevitably blow out from the other end, because the pipe changes the direction of the wind, forcing the wind direction disrupted by the windmill to return to its original direction. But wind turbines are built in the wilderness, and the wind flows freely without a pipe to restrain it. The wind blows from one direction, and after passing the wind turbine, its direction is disrupted and its speed is reduced.
2. I don’t quite understand this question.
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 just 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 rotate. During this process, the wind does work 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 down because work is done on the wall - the same principle as a generator.
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Additional 2:
1. As the poster said, the air entering the duct is continuous. Theoretically, the wind enters A uniform duct (same duct cross-section) and the instantaneous velocity leaving the duct should be the same because there is no loss of air volume. This should cause all fans to spin.
The condition we assume here is a cylindrical pipe with the same cross-section. Because the wind direction remains unchanged, we came to the above conclusion. The original poster had previously assumed a small box with two opposite holes. If it is a square box (the kind with edges), it is difficult to say whether to open two holes on each opposite side. Because gas vortices will occur in the corners of the square box, we must also 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 fan blades are stationary, the gap between them is indeed large; but once the fan blades rotate, the gap between them will become smaller. The faster the speed, the smaller the gap. For example, an electric fan, when it worksCan you see the gaps between its leaves? ----cannot. But when you turn off the switch, the fan blades rotate slower and slower, and the gaps become more and more obvious.
So, when the blades of the wind turbine are stationary or rotate slowly, there will be breeze or air passing between the blades; when the wind speed increases and the blades rotate faster and faster, there will be no gaps. doubts.