Wind Speed Sensor Working Principle
The wind speed sensor is a kind of meteorological equipment that can continuously measure the wind speed and volume. Wind speed sensor according to the acoustic principle is roughly divided into mechanical (mainly propeller type and wind cup type), hot air, air tube and ultrasonic wind speed sensor.
First, the working principle of propeller wind speed sensor
We know that the electric fan is driven by the motor to rotate the fan blades, which creates a pressure difference between the front and back of the blades, which promotes the flow of air. The working principle of the propeller anemometer is just the opposite. The blade system aligned with the airflow is subjected to wind pressure, and a certain torsion moment is generated to rotate the blade system. Usually the propeller speed sensor measures the wind speed by rotating a group of three-blade or four-blade propellers around a horizontal axis. The propeller is usually installed in the front of a weathervane so that its rotating plane is always facing the direction of the wind, and its speed is proportional to the wind speed.
Second, the working principle of the wind cup wind speed sensor
Wind-cup wind speed sensor is a very common wind speed sensor, which was invented by Ruby Sun in England. The sensing part is composed of three or four cone-shaped or hemispherical empty cups. The hollow cup shell is fixed on a three-pronged star bracket that is 120° or a cross-shaped bracket that is 90°. The concave surfaces of the cup are arranged in one direction, and the entire cross arm frame is fixed on a vertical rotation axis.
When the wind blows from the left, the wind cup 1 is parallel to the wind direction, and the force component of the pressure on the wind cup 1 in the direction straight to the axis of the wind cup is approximately zero. Wind cups 2 and 3 intersect with the wind direction at an angle of 60 degrees. For wind cup 2, its concave surface faces the wind and bears the wind pressure; wind cup 3 has a convex surface facing the wind, and the wind’s circumfluence makes the wind pressure more than The wind cup 2 is small. Due to the pressure difference between the wind cup 2 and the wind cup 3 in the direction perpendicular to the axis of the wind cup, the wind cup starts to rotate in a clockwise direction. The greater the wind speed, the greater the initial pressure difference and the resulting acceleration The larger, the faster the wind cup rotates.
After the wind cup starts to rotate, because the cup 2 rotates in the direction of the wind, the pressure of the wind is relatively reduced, and the cup 3 rotates at the same speed against the wind, the wind pressure is relatively increased, and the wind pressure difference After a period of time (when the wind speed is constant), when the partial pressure difference acting on the three wind cups is zero, the wind cups will rotate at a constant speed. In this way, the wind speed can be determined according to the speed of the wind cup (the number of turns per second).
When the wind cup rotates, it drives the coaxial multi-tooth cutting disc or magnetic rod to rotate, and the pulse signal proportional to the speed of the wind cup is obtained through the circuit. The pulse signal is counted by the counter, and the actual value can be obtained after conversion. Wind speed value. At present, the new rotor anemometer adopts three cups, and the performance of the cone cup is better than that of the hemispherical cup.
When the wind speed increases, the rotor cup can quickly increase the speed to adapt to the airflow speed. When the wind speed decreases, due to the influence of inertia, the speed However, it cannot drop immediately. The wind speed indicated by the rotary anemometer in gusty wind is generally too high, which becomes an excessive effect (the average error produced is about 10%).