Basics about digital anemometers
Wind speed (flow velocity) testing includes testing of average wind speed and testing of turbulent components (wind turbulence 1-150KHz, different from variations). A thermal anemometer is used to test the average wind speed. There are methods for testing average wind speed, such as thermal, ultrasonic, impeller, and pitot tube, but among these methods, the * * anemometer utilizes the principle of heat dissipation. Below, we will explain the methods for measuring these wind speeds.
Thermal anemometer
This method is to test the resistance change caused by the cooling of the sensor due to wind when it is powered on, and thus test the wind speed. Unable to obtain information on wind direction. In addition to being easy and convenient to carry, it has a high cost performance ratio and is widely used as a standard product for anemometers.
The elements of the thermal anemometer include platinum wire, thermocouple, and semiconductor, but our company uses platinum winding wire. The material of platinum wire is materially stable. Therefore, it has advantages in long-term stability and temperature compensation.
ultrasonic type
This method is to test the transmission time of ultrasonic waves at a certain distance, and the arrival time is delayed due to the influence of wind, in order to test the wind speed. At the third power, the wind direction can be determined. The sensor section is relatively large, and turbulence may occur around the testing section, causing irregular flow. The use is limited. Low popularity.
Impeller type
This method applies the principle of windmills by testing the rotational speed of the impeller and the wind speed. Used for meteorological observation, etc. The principle is relatively simple and the price is cheap, but the testing accuracy is low, so it is not suitable for testing light wind speed and small wind speed changes.
Pitot tube type
On the front of the flow surface, there are small holes that form a right angle with it, and inside there are thin tubes that extract pressure from each hole. By testing its pressure difference (the former being full pressure and the latter being static pressure), the wind speed can be determined.
The principle is relatively simple and the price is cheap, but it must be set at a right angle to the flow surface, otherwise it cannot be tested correctly. Not suitable for general use.
