1. All three are related to wind
2 There is a certain relationship between the three when one of them remains unchanged
At a certain time within a given time frame. certain space, when the wind pressure remains unchanged: the greater the wind speed, the greater the wind volume;
In a certain period of time, in a certain space, when the volume of The air remains constant: the higher the wind pressure, the greater the wind speed.
Detailed information:
Types of wind speed measuring instruments< /p>
① Cup anemometer. This is the most common type of anemometer. The rotating cup anemometer was first invented by the British J.T.R. Robinson (1846). He used four cups at the time, then moved to three cups. Three empty parabolic or hemispherical cups fixed on the support at 120 degrees from each other are aligned on un side, and the entire support as well as the wind cup are mounted on a shaft which can rotate freely.
Under the action of the force of the wind, the wind cup rotates around its axis and its rotation speed is proportional to the wind speed. The rotational speed can be recorded using electrical contacts, tachometer generators or photoelectric meters.
②Propeller anemometer. It is an anemometer with a set of propellers with three or four blades rotating around a horizontal axis. The propeller is mounted on the front of a weather vane so that its plane of rotation always faces the direction of the wind and its speed of rotation is proportional to the wind speed.
③Hot wire anemometer. A metal wire is heated by an electric current and the circulating air dissipates the heat. The heat dissipation rate is linearly related to the square root of the wind speed, then linearized via electronic circuits (for easy scaling and reading), a hot wire. an anemometer can be made. Hot wire anemometers are divided into two types: side heating type and direct heating type. Laterally heated hot wires are usually manganese-copper wires, the thermal resistance coefficient of which is close to zero, and on its surface there is a temperature measuring element.
Direct heating hot wires are mainly made of platinum wire, which can directly measure the temperature of the hot wire itself while measuring the wind speed. The hot wire anemometer has high sensitivity to low wind speeds and is suitable for measuring small wind speeds. With a time constant of only a few hundredths of a second, it is an important tool for measuring atmospheric turbulence and agricultural meteorology.
④Acoustic anemometer. The component ofWind speed in the direction of sound wave propagation will increase (or decrease) the speed of sound wave propagation. An acoustic anemometer made using this feature can be used to measure the wind speed component. Acoustic anemometers have at least two pairs of sensing elements, one for each pair comprising a sounder and a receiver.
Make the sound wave propagation directions of the two sounders in opposite directions. If one set of sound waves propagates along the wind speed component and the other set propagates just against the wind, the time difference between the two receivers is calculated. the reception of the sound pulse will be proportional to the wind speed component.
If two pairs of components are installed simultaneously in the horizontal and vertical directions, the horizontal wind speed, directionwind speed and vertical wind speed can be calculated respectively. Since ultrasonic waves have the advantages of anti-interference and good directivity, the frequency of sound waves emitted by the acoustic anemometer is mainly in the ultrasonic band.
Baidu Encyclopedia - Wind Speed
Baidu Encyclopedia - Wind
Baidu Encyclopedia - Wind Pressure
Baidu Encyclopedia - Wind Volume
< /p>Although there are many types of wind turbines, they can be summarized into two categories: ① Horizontal axis wind turbines, the rotation axis of the wind wheel is parallel to the wind direction ② Vertical axis wind turbines, the axis of rotation of the wind turbine; The wind wheel is perpendicular to the ground or the direction of air flow. There are several types of vertical axis wind turbines that use resistance to rotate, including wind turbines made of flat platesand cups, which are pure resistance devices; S-type wind turbines, which have some lift but are primarily resistance devices. These devices have a large starting torque, but a low tip speed ratio, and provide low power output when the size, weight and cost of the wind turbine are certain.
The Darrieux style wind turbine was invented by the Frenchman G.J.M. Darrieux in the 1830s. In the 1970s, the National Academy of Sciences of Canada conducted a lot of research on this subject and was the main competitor to horizontal axis wind turbines. The Darrieux wind turbine is a lifting device. The profile of the curved blades is a sail. Its starting torque is low, but the peak speed ratio can be very high. For a given weight and cost of the wind turbine, it presents a high ratio. output power. There are many types of wind turbinesDarieux type in the world, such as Φ type, Δ type, Y type and H type, etc. These rotors can be designed in single-blade, double-blade, three-blade or multi-blade versions.
Other forms of vertical axis wind turbines include the Magnus effect wind wheel, which consists of a rotating cylinder. When operating in the airflow, the displacement force generated is due to the Magnus effect caused by the Sri. Lankan effect, its size is proportional to the speed of the wind. Some vertical axis wind turbines use pipes or vortex generating towers to transform horizontal airflow into vertical airflow through housings or diffusers to increase speed. Sometimes they also use solar energy or burn some kind of fuel to transform horizontal airflow into vertical airflow.