About Anemometers How Anemometers Work
Selection of probe for anemometer
The measurement range of flow velocity from 0 to 100m/s can be divided into three sections: low speed: 0 to 5m/s; Medium speed: 5 to 40m/s; High speed: 40 to 100m/s. The thermal sensitive probe of the anemometer is used for precise measurement from 0 to 5m/s; The rotary probe of the anemometer performs well in measuring flow velocities ranging from 5 to 40m/s; By using a pitot tube with an anemometer, better results can be obtained at high speeds. An additional criterion for correctly selecting the flow velocity probe of an anemometer is temperature, and typically the temperature range for the thermal sensor of an anemometer is around+-70C. The rotary probe of the specially designed anemometer can reach up to 350C. Pitot tubes are used for temperatures above+350C. The specific details are as follows:
Thermal sensitive probe of anemometer
The working principle of the thermal sensitive probe of the anemometer is based on the cold shock airflow carrying away the heat from the heating element. With the help of an adjustment switch, the temperature is kept constant, and the current and flow rate are proportional to each other. When using a thermal sensitive probe in turbulence, airflow from all directions simultaneously impacts the thermal element, which can affect the accuracy of the measurement results. When measuring in turbulence, the reading of the thermal anemometer flow sensor is often higher than that of the rotary probe. The above phenomenon can be observed during pipeline measurement. According to different designs for managing turbulent flow in pipelines, it may even occur at low speeds. Therefore, the anemometer measurement process should be carried out in the straight section of the pipeline. The starting point of the straight section should be at least 10 × D (D=pipe diameter, in CM) outside the measurement point; The endpoint should be at least 4 × D behind the measurement point. The fluid cross-section must not have any obstruction. (Sharp edges, heavy suspension, objects, etc.)
Wheel type probe of anemometer 2
The working principle of the anemometer's rotary probe is based on converting rotation into electrical signals. First, it passes through a proximity sensing head to "count" the rotation of the rotor and generate a pulse series. Then, it is converted and processed by the detector to obtain the speed value. The large-diameter probe (60mm, 100mm) of the anemometer is suitable for measuring turbulent flow with medium to low velocities (such as at pipeline outlets). The small aperture probe of the anemometer is more suitable for measuring airflow in pipelines with a cross-section larger than that of the exploration head by more than 100 times
