The most common specific categories of anemometers
Wind cup anemometer
It is the most common type of anemometer. The rotating cup anemometer was first invented by Robinson Crusoe in the UK, initially with four cups, but later switched to three cups. Three parabolic or hemispherical empty cups fixed to each other on the frame are aligned, and the entire frame, along with the air cup, is mounted on a freely rotatable shaft. Under the action of wind, the wind cup rotates around its axis, and its speed is proportional to the wind speed. The speed can be recorded using electrical contacts, tachometers, or photoelectric counters.
Propeller anemometer
It is an anemometer with a set of three or four bladed propellers rotating around a horizontal axis. The propeller is installed at the front of a wind vane, so that its rotation plane is always facing the direction of the wind, and its speed is proportional to the wind speed.
Propeller anemometer
An anemometer with a propeller rotating around a horizontal axis. The propeller is installed at the front of a wind vane, so that its rotation plane is always facing the direction of the wind, and its speed is proportional to the wind speed. An anemometer is a metal wire heated by an electric current, which is cooled by flowing air. The heat dissipation rate is linearly related to the square root of the wind speed, and then linearized through electronic circuits (for ease of calibration and reading) to make an anemometer. There are two types of wind speed scoring: side heating and direct heating. The side heating type is generally made of manganese copper wire, with a temperature coefficient of resistance close to zero, and a temperature measuring element is placed on its surface.
The direct heating type is mostly platinum wire, which can directly measure its own temperature while measuring wind speed. Anemometers have high sensitivity at low wind speeds and are suitable for measuring low wind speeds. Its time constant is only a few percent of a second, making it an important tool for measuring atmospheric turbulence and agricultural meteorology.
Acoustic anemometer
The wind speed component in the direction of sound wave propagation will increase (or decrease) the speed of sound wave propagation, and acoustic anemometers made using this characteristic can be used to measure the wind speed component. The acoustic anemometer has at least two pairs of sensing elements, each pair including a speaker and a receiver. Make the sound waves of two speakers propagate in opposite directions. If one set of sound waves propagates along the wind speed component and the other set propagates against the wind, the time difference between the two receivers receiving the sound pulse will be proportional to the wind speed component. If two pairs of components are installed in both horizontal and vertical directions, the horizontal wind speed, wind direction, and vertical wind speed can be calculated separately. Due to the advantages of anti-interference and good directionality of ultrasound, the frequency of sound waves emitted by acoustic anemometers is mostly in the ultrasound band.
