Wind speed testing methods and anemometer classification
The wind speed (flow speed) test includes the test of average wind speed and the test of turbulence component (wind turbulence 1 to 150KHz, different from fluctuation). Thermal anemometer measures average wind speed. Methods for testing average wind speed include thermal, ultrasonic, impeller, and leather drag tube types. However, among these methods, the ** type anemometer uses the principle of heat dissipation. Next, the methods for measuring these wind speeds will be explained.
1. Thermal anemometer
・This method tests the wind speed by testing the resistance change that occurs when the sensor is cooled by the wind while the power is on. No information about wind direction can be obtained.
・In addition to being easy to carry and convenient, it has a high cost-performance ratio and is widely used as a standard product of anemometers.
・The elements of thermal anemometers include those using platinum wire, thermocouples, and semiconductors.
2. Ultrasonic type
・This method tests the time it takes to transmit ultrasonic waves over a certain distance. The arrival time is delayed due to the influence of wind, thereby testing the wind speed.
・When raised to the third power, the wind direction can be known.
・The sensor part is large, and turbulence may occur around the test part, causing the flow to become irregular. Usage restricted.
・Low popularity.
3. Impeller type
・This method applies the principle of a windmill to test the wind speed by testing the rotation number of the impeller.
・Used for weather observation, etc.
・The principle is relatively simple and the price is cheap, but the test accuracy is low, so it is not suitable for testing of light wind speed and small wind speed changes.
・Low popularity.
4. Leather tube type
・There are small holes at right angles to the front side of the flow surface, and there are thin tubes inside that extract pressure from each hole. By testing the pressure difference (the former is full pressure and the latter is static pressure), the wind speed can be known.
・The principle is relatively simple and the price is cheap, but it must be set at right angles to the flow surface, otherwise correct testing cannot be performed. Not suitable for general use.
・It is not used as an anemometer but for wind speed correction in the high-speed range.
