A device for measuring wind speed or air flow is called an anemometer. Commercial instruments are quite expensive, but you can try to make an anemometer yourself using an electric motor.
Making an anemometer with your own hands: the nuances of work
For the manufacture of a device that measures the speed of an air flow, you will need improvised means. For example, you can use halves of plastic Easter eggs as anemometer blades. A compact brushless permanent magnet motor is also required. The main thing is that the resistance of the bearings on the motor shaft is minimal. This requirement is due to the fact that the wind can be very weak, and then the motor shaft will simply not turn. To create an anemometer, a motor from an old hard drive will do.
The main difficulty in assembling an anemometer is how to make a balanced rotor. The engine will need to be installed on a massive base, and a disc made of thick plastic should be placed on its rotor. Then, three identical hemispheres must be carefully cut out of plastic eggs. They are fixed to the disc using studs or steel rods. In this case, the disk must first be divided into sectors of 120 degrees.
Balancing is recommended to be carried out in a room where all wind movements are completely absent. The axis of the anemometer must be in a horizontal position. Weight adjustment is usually done using file files. The point is for the rotor to stop in any position, not in the same position.
Calibration of the instrument
A homemade device must be calibrated. It is best to use a car for calibration. But you will need some kind of mast so that the anemometer does not fall into the zone of disturbed air generated by the car. Otherwise, the readings will be highly distorted.
Calibration should only be performed on a calm day. Then the process will not drag on. If the wind blows, you will have to drive on the road for a long time and calculate the average values of the wind speed. It should be borne in mind that the speed of the speedometer is measured in km / h, and the wind speed in m / s. The ratio between them is 3, 6. This means that the speedometer readings will need to be divided by this number.
Some people use a voice recorder during the calibration process. You can simply dictate the readings of the speedometer and anemometer to an electronic device. At home, you can create a new scale for your homemade anemometer. Only with the help of a properly calibrated device can you obtain reliable data on the wind conditions in the required area.