How the anemometer works

A velocity meter that converts velocity signals into electrical signals and also measures fluid temperature or density. The principle is that a thin wire (called hot wire) heated by electricity is placed in the airflow. The heat dissipation of the hot wire in the airflow is related to the flow velocity. The heat dissipation leads to the temperature change of the hot wire and causes the change of resistance.







It has two modes of operation:







Constant flow type. When the temperature changes, the resistance of the hot wire changes. Therefore, the voltage at both ends changes. Thus, the flow rate is measured.







(2) constant temperature. Hotline temperature remains constant, such as 150 ℃, applying current can be measured according to the required flow rate.







The constant temperature type is more widely used than the constant current type.







Besides the ordinary single wire, the hot wire can also be combined double wire or triple wire to measure the velocity component in all directions. The electrical signals output from the hot wire can be amplified, compensated and digitized and then input into the computer to improve the measurement accuracy, automatically complete the data post-processing process, and expand the speed measurement function, such as simultaneous measurement of instantaneous value and time mean value, combined speed and divided speed, turbulivity and other turbulence parameters.