(Suppliers: A 2)
2.5.223 Instruments using the heat transfer method.
- In "hot wire anemometers, an electrically heated wire is
cooled by the airflow. As the amount of heat loss is
proportional to the wind speed at normal incidence of the
air ourrent, this principle can be used to measure the wind
speed.
The heat loss of the exposed wire results in a temperature
difference to an unexposed control wire. This differential
temperature is usually controlled with thermocouples.
Either the temperature difference is used to deduce the
speed of the airflow or the exposed wire is heated up to
the temperature of the unexposed one, in which case the
current required can be referred to the windspeed.
Vertical mounting of the measuring wires makes this
instrument independent of the direction of the wind in one
plane.
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