Correlation Measurements with Field Anemometers
On-site anemometer measurement is mainly divided into three types: differential pressure type, impeller type, and thermal ball type;
The differential pressure method is a classic method of measuring flow velocity in fluid mechanics. It mainly relies on the pitot tube and differential pressure gauge to measure the dynamic pressure, and then calculates the flow velocity according to the Bernoulli equation.
The advantage of this method is that the detection limit is low and the sensitivity is high, but it has high requirements on the uniformity of the flow field, and it is easy to be inaccurate due to the uneven flow field when measuring in the environment. Therefore, the differential pressure method is mainly used to measure the wind speed in the air duct. .
The main principle of the hot bulb type is that the probe sets a constant temperature, and the heat will be taken away after the air flows through the probe. At this time, the probe will be heated to the set temperature. Calculate the wind speed.
The advantages of this method are high sensitivity, large measuring range, and suitable for environmental measurement. The disadvantage is that the platinum wire connected to the heat ball in the probe is relatively fragile. If you are not careful during use, the probe will easily be damaged and cannot be repaired.
At present, the domestic thermal bulb anemometer is still an old-fashioned anemometer. The Air Conditioning Institute of the Construction Research Institute has a more advanced alternative technology, replacing the thermal bulb with a ceramic thermal column, which is much stronger than the thermal bulb.
The impeller type mainly relies on the wind to blow the impeller to rotate and generate electromagnetic signals for measurement. The advantage of this method is that the instrument is more durable;
Commonly used for long-term measurement, the three-cup anemometer used in meteorological observation also has the same principle, but the disadvantage is that the sensitivity is slightly poor.
