How the wind cup wind speed sensor works

How the wind cup wind speed sensor works

The wind cup wind speed sensor, a very common wind speed sensor, was first invented by Rubenson in England. The sensing part consists of three or four conical or hemispherical empty cups. The hollow cups are fixed on trigonal star-shaped brackets at 120° to each other or on cross-shaped brackets at 90° to each other, with the concave surfaces of the cups aligned in one direction and the entire cross-arm frame fixed on a vertical axis of rotation.

When the wind is blowing from the left, wind cup 1 is parallel to the wind direction and the pressure of the wind on cup 1 is approximately zero in the direction straightest to the wind cup axis. The wind cup 2 and 3 intersect with the wind direction at an angle of 60 degrees, for the wind cup 2, its concave surface facing the wind, the wind pressure is the largest; wind cup 3 its convex surface facing the wind, the wind around the role of the wind so that the wind pressure than the wind cup 2 small, due to the wind cup 2 and the wind cup 3 in the direction of the wind cup axis perpendicular to the pressure difference, and the wind cup began to rotate clockwise direction, the greater the wind speed, the greater the starting pressure difference, the greater the acceleration, the wind cup rotation The greater the wind speed, the greater the initial pressure difference, the greater the acceleration, and the faster the wind cup turns.

After the wind cup starts to rotate, as cup 2 rotates in the direction of the wind, the pressure of the wind decreases, while cup 3 rotates at the same speed against the wind, the pressure of the wind increases, the wind pressure difference decreases, and after a period of time (when the wind speed remains unchanged), the partial pressure difference between the three cups is zero, and the wind cups rotate at a constant speed. The wind speed can then be determined according to the speed of the cups (revolutions per second).

When the wind cup rotates, it drives the coaxial multi-tooth cut-off disc or magnetic rod to rotate, and through the circuit to get a pulse signal proportional to the wind cup speed, the pulse signal is counted by the counter, and after conversion, the actual wind speed value can be derived.

When the wind speed increases, the rotating cup can rapidly increase the rotational speed to adapt to the airflow speed, and when the wind speed decreases, the rotational speed cannot drop immediately due to the inertia, the rotating anemometer in the gust of wind indicates the wind speed is generally on the high side to become too high effect (the average error is about 10%).