What are the differences between the different anemometers?
According to the principle, there are three main types of on-site anemometer measurement: differential pressure type, impeller type, and hot ball type:
The differential pressure method is a classic method of measuring flow velocity in fluid mechanics. It mainly relies on a pitot tube and a differential pressure meter to measure the dynamic pressure, and then calculates the flow velocity based on the Bernoulli equation.
The advantages of this method are low detection limit and high sensitivity, but it requires high flow field uniformity;
When measuring in the environment, it is easy to be inaccurate due to uneven flow fields. Therefore, the pressure difference method is mainly used to measure wind speed in air ducts.
The main principle of the hot ball type is that the probe sets a constant temperature, and the air will take away the heat after flowing through the probe;
At this time, the probe will be heated to the set temperature. During this process, electrical signals will be collected by the instrument, and the wind speed will be calculated accordingly.
The advantages of this method are high sensitivity, large range, and adaptability to environmental measurements. The disadvantage is that the platinum wire connecting the hot ball in the probe is relatively fragile. If you are not careful during use, the probe may be damaged and cannot be repaired.
At present, the domestic hot ball anemometer is still an old-fashioned anemometer. The Air Conditioning Institute of the Institute of Construction Research has developed a more advanced alternative technology. The hot ball is replaced by a ceramic hot column, which is much stronger than the hot ball.
The impeller type mainly relies on wind to rotate the impeller and generate electromagnetic signals for measurement. The advantage of this method is that the instrument is more durable;
Commonly used for long-term measurements, the three-cup anemometer used in meteorological observations also uses the same principle, but the disadvantage is that the sensitivity is slightly lower.
