CALIBRATION PROCEDURE

The calibration procedure is as follows:

1.- The anemometer is installed in the wind tunnel.

2.- Wind tunnel is switched on.

3.- Flow velocity is varied. The value of the velocities and the total amount of points measured depends on the calibration, and can be adjusted.

4.- For each velocity, the output signal of the anemometer is measured. This signal is usually a voltage.

5.- Throughout all the process, environmental conditions (pressure, temperature and humidity) are also measured with instruments calibrated in ENAC-recognized laboratories.

The result of the calibration process is a curve in which the output of the anemometer and the wind velocity are related. At the end, a calibration certificate is issued.

To calibrate an anemometer, it is installed in the S4 wind tunnel test chamber and subjected to the air flow generated by the wind tunnel. The flow velocity is varied between 4 m/s and 23 m/s for an AD calibration and between 4 m/s and 16 m/s for an AC calibration. Within these ranges, 9 to 13 points are taken at which the wind tunnel reference velocity and the anemometer output, which is usually an electrical voltage or variable frequency signal, are measured simultaneously. Environmental conditions (pressure, temperature and humidity) are also measured during calibration. All these measurements are performed with instruments calibrated by ENAC-accredited laboratories.
Vector A100 anemometer	RM Young 05103 anemometer
The calibration result can be presented as a curve relating the anemometer output to the reference velocity measured in the tunnel. After the calibration is completed, a certificate is issued documenting the results obtained.
Example of the calibration curve of an anemometer