Explanation of four common anemometers
1 Anemometer. A metal wire heated by an electric current is dissipated by the flowing air. The heat dissipation rate is linearly related to the square root of the wind speed, and then linearized through an electronic circuit (for easy calibration and reading) to create 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 resistance temperature coefficient close to zero, and it is equipped with a temperature measuring element on its surface. Direct heating is mostly made of platinum wire, which can directly measure its own temperature while measuring wind speed. The anemometer has high sensitivity at low wind speeds and is suitable for measuring small wind speeds. Its time constant is only a few percent of a second, making it an important tool for atmospheric turbulence and agricultural meteorological measurements.
2 wind cup anemometers. It is a common type of anemometer. The rotary anemometer * was invented by Robinson in England as early as the time, it was four cups, and later changed to three cups. Three parabolic or hemispherical empty cups fixed on the frame with mutual complementarity are all aligned on one side, and the entire frame, along with the air cup, is mounted on a freely rotating axis. 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, speed measuring generators, or photoelectric counters.
3 acoustic anemometers. 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 group of sound waves propagates along the wind speed component and the other group precisely propagates against the wind, the time difference between the two receivers receiving sound pulses 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, 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.
4 propeller type anemometer. It is an anemometer with a set of three or four bladed propellers rotating around the horizontal axis. The propeller is installed at the front of a wind vane, so that its rotating plane is always facing the direction of the wind, and its speed is proportional to the wind speed.
