Measurement Technology of Anemometer

The anemometer measures the airflow velocity in the pipeline:

Practice has proved that the 16mm probe of the anemometer is the most widely used. Its size not only ensures good permeability, but also can withstand flow rates up to 60m/s. As one of the feasible measurement methods, the measurement of airflow velocity in the pipeline, the indirect measurement procedure (grid measurement method) is suitable for air measurement.

Measurement of anemometer in the extraction exhaust:

The vent will greatly change the relatively balanced distribution of the airflow in the duct: a high-speed area will be generated on the surface of the free vent, and the rest will be a low-speed area, and vortices will be generated on the grid. According to the different design methods of the grid, at a certain distance (about 20cm) in front of the grid, the airflow section is relatively stable. In this case, the caliber runner of a large anemometer is usually used for measurement. Because the larger diameter can average the unbalanced flow velocity and calculate its average value over a larger range.

The anemometer uses a volumetric flow funnel to measure at the suction hole:

Even if there is no grid interference at the extraction, the air flow has no direction and its air flow cross section is extremely uneven. The reason is that the partial vacuum in the pipeline draws the air out of the air chamber in a funnel shape. Even in the area very close to the air extraction, there is no position that meets the measurement conditions and can be used for measurement operations.

If the grid measurement method with averaging function is used for measurement, and the volume flow method is used for measurement, and the volume flow method is used to determine the volume flow, etc., only the pipe or funnel measurement method can provide repeatable measurement results. In this case, measuring funnels of different sizes can meet the requirements of use. Using the measuring funnel, a fixed section that meets the flow velocity measurement conditions can be generated at a certain distance in front of the flap valve, and the center of the section is determined and fixed here. The measured value obtained by the flow rate probe is multiplied by the funnel coefficient to calculate the extracted volume flow (such as the funnel coefficient of 20).

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