Selection and purchase of anemometer probes
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 * * measurement from 0 to 5m/s; The rotary probe of the anemometer measures a flow velocity of 5 to 40m/s with ideal results; By using a pitot tube, excellent results can be obtained in the high-speed range. An additional standard for selecting the flow rate probe of an anemometer correctly is temperature, which is typically used by the thermal sensor of the anemometer at temperatures of approximately+-70C. The rotor probe of the specially designed anemometer can reach 350C. Pitot tubes are used for temperatures above+350C.
Thermosensitive probe of anemometer
The working principle of the thermal sensitive probe of the anemometer is based on the cold impact airflow taking away the heat on the thermal element. With the help of a regulating switch, the temperature is kept constant, and the regulating current is proportional to the flow rate. When using a thermosensitive 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 flow velocity sensor of the thermal anemometer is often higher than that of the rotary probe. The above phenomena can be observed during pipeline measurement. According to different designs for managing pipeline turbulence, it can even occur at low speeds. Therefore, the anemometer measurement process should be carried out on the straight section of the pipeline. The starting point of the straight section should be at least 10 times before the measurement point × D (D=pipeline diameter, in CM); The endpoint should be at least 4 after the measurement point × Location D. The fluid cross-section must not have any obstruction. (edges, overhangs, objects, etc.)
Positioning of Anemometers in Air Flow
The correct adjustment position of the rotary probe of the anemometer is that the airflow direction is parallel to the rotary axis. When the probe is gently rotated in the airflow, the reading will change accordingly. When the reading reaches the maximum value of *, it indicates that the probe is in the correct measurement position. When measuring in a pipeline, the distance from the starting point of the straight part of the pipeline to the measurement point should be greater than 0XD, and the influence of turbulence on the thermal sensitive probe and pitot tube of the anemometer is relatively small.
Measurement of airflow velocity in pipelines using an anemometer
Practice has proven that the 16mm probe of the anemometer has a wide range of applications. Its size ensures good permeability and can withstand flow rates up to 60m/s. The measurement of airflow velocity in pipelines is one of the feasible measurement methods, and the indirect measurement regulation (grid measurement method) is applicable to air measurement.
