Wind speed refers to the movement speed of air relative to a fixed location on the earth. The common unit is m/s, 1m/s = 3.6 km/h. There is no level of wind speed, but only the level of wind, and wind speed is the basis for the classification of wind power. Generally speaking, the higher the wind speed and the higher the wind level, the more destructive the wind is. Wind speed is one of the main parameters of climatology research. The measurement of atmospheric wind plays an important role and significance for global climate change research, aerospace and military applications.
Air volume refers to the flow of air per unit of time. It is generally used to indicate the capacity of blowers or ventilation equipment. The unit of calculation is cubic meters per second. When the material of the heat sink is the same, the air volume is the most important indicator to measure the heat dissipation capacity of the air-cooled radiator. Obviously, the larger the air volume, the higher the heat dissipation capacity of the radiator. This is because the heat capacity of the air is constant, and a larger air volume, that is, more air per unit time, can take away more heat. Of course, in the case of the same air volume, the heat dissipation effect is related to the flow of the wind.
What is the difference between wind speed sensor and air volume sensor?
The wind speed and the air volume are different, but there is a certain relationship between the two. The air volume is equal to the product of the wind speed and the cross-sectional area of the vent. Therefore, the data of the air volume sensor is mostly converted from the measurement data of the wind speed sensor.
The conversion method is:
L(m/h)=3600F(㎡)V(m/s)
In the formula: L represents the air volume F represents the ventilation area of the tuyere V represents the measured average wind speed of the tuyere. The cup-type wind speed sensor is a very common wind speed sensor, which was first invented by Robinson in the United Kingdom. The induction part is composed of three or four conical or hemispherical empty cups. The hollow cup shell is fixed on a three-pointed star-shaped bracket that is 120° to each other or a cross-shaped bracket that is 90° to each other. The concave surface of the cup is arranged in one direction, and the entire cross arm 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 component force of the wind pressure on the wind cup 1 in the direction most straight to the wind cup axis is approximately zero. Wind cups 2 and 3 intersect with the same wind direction at a 60-degree angle. For wind cup 2, its concave surface faces the wind and bears the largest wind pressure; wind cup 3 has its convex surface facing the wind, and the wind’s flow around it makes it subject to wind pressure. It is smaller than the wind cup 2. Due to the pressure difference between the wind cup 2 and the wind cup 3 in the direction perpendicular to the wind cup axis, the wind cup starts to rotate clockwise. The higher the wind speed, the greater the initial pressure difference. The greater the acceleration, the faster the wind cup turns.
After the wind cup starts to rotate, since the cup 2 rotates in the direction of the wind, the pressure of the wind is relatively reduced, while the cup 3 rotates against the wind at the same speed, the wind pressure is relatively increased, and the wind pressure difference continues to decrease. , 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 uniform speed. In this way, the wind speed can be determined according to the rotation speed of the wind cup (the number of revolutions 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 rotation speed of the wind cup is obtained through the circuit. The pulse signal is counted by the counter, and the actual wind speed value can be obtained after conversion. At present, the new rotor anemometers all use three cups, and the performance of the conical cup is better than that of the hemispherical cup. When the wind speed increases, the rotor can rapidly increase the rotation speed to adapt to the airflow speed. When the wind speed decreases, due to the influence of inertia, the rotation speed The wind speed indicated by the rotary anemometer in a gust is generally too high to become a high effect (the resulting average error is about 10%).