Solution to measuring wind speed with anemometer
Anemometer probe can be selected from: thermal probe, impeller probe, pitot tube
Wind speed can be divided into three measurement zones: low wind speed from 0 to 5m/s, medium wind speed from 5 to 40m/s, and high wind speed from 40 to 100m/s
Pitot tube - mainly used in high temperature measurement
The opening of the pitot tube receives the total pressure and guides it into the force connection of the pressure probe (a). Pure static pressure is filled into the side slot and introduced into the connection (b) of the pressure probe. The differential pressure generated is the wind speed pressure (pressure related to dynamic flow) that is subsequently analyzed and indicated. When using a thermal probe, the pitot tube is more suitable for reacting to turbulence than the impeller. Therefore, during the measurement of the pitot tube, it is also necessary to ensure free inlet and outlet channels
Pressure offset
Due to the use of an average air density of 1200g/m3 in calculations, measurement errors often occur. When measuring the airflow outside the window, the actual air density may deviate from the given average value by ± 10%. Therefore, it may result in an air volume deviation of ± 5%. The testo 400 can compensate for this error by enabling automatic conversion of pitot tube pressure to wind speed. Then, multi-point averaging calculations can be directly performed on these m/s values.
The thermal probe measurement method is based on the principle of air cooling factors. An object is heated to a fixed temperature and then placed in an airflow. Determine the clearly indicated wind speed by measuring the amount of energy required to maintain the previous temperature. The higher the wind speed, the more energy is required to maintain a stable temperature. Thermal anemometers can be implemented using either a hot bulb probe or a thermal bulb probe.
Anemometer impeller probe - suitable for high wind speed measurement
The measurement principle of the impeller probe is based on the conversion of rotation to electrical signals. The induction proximity switch "counts" the number of revolutions of the impeller and provides a pulse sequence converted in the instrument, which is then used as an indication of the wind speed value. Large diameter probes (60 mm, 100 mm) are suitable for measuring turbulence at small or moderate wind speeds (such as outlet pipelines). Small diameters are more suitable for measurement in pipelines, in which case the cross-section of the pipeline must be 100 times larger than that of the probe. The 16mm probe has been proven to be very versatile. It is large enough to balance turbulence and small enough to be easily inserted into pipelines. Correctly adjust the impeller probe in the airflow to ensure that the airflow direction is parallel to the impeller axis.
