Working mode of anemometer Anemometer
An anemometer is a speed measuring instrument that converts a flow velocity signal into an electrical signal, and can also measure fluid temperature or density. The principle is that a thin metal wire heated by electricity (called a hot wire) is placed in the airflow, the heat dissipation of the hot wire in the airflow is related to the flow velocity, and the heat dissipation causes the temperature change of the hot wire to cause a change in resistance, and the flow velocity signal is transformed into electric signal.
It has two working modes:
①Constant flow type. The current through the hot wire remains constant. When the temperature changes, the resistance of the hot wire changes, so the voltage across the two ends changes, thereby measuring the flow rate;
②Constant temperature type. The temperature of the hot wire is kept constant, such as 150°C, and the flow rate can be measured according to the required applied current.
The constant temperature type is more widely used than the constant flow type.
In addition to the ordinary single-wire type, the hot wire can also be a combined double-wire or three-wire type to measure the velocity components in all directions. The electrical signal output from the hotline is input into the computer after amplification, compensation and digitization, which can improve the measurement accuracy, automatically complete the data post-processing process, and expand the speed measurement function, such as simultaneously completing the instantaneous value and time average value, combined speed and partial speed, and turbulence. and other measurements of turbulence parameters.
