The wind speed sensor can continuously monitor the wind speed and air volume (air volume = wind speed x cross-sectional area) of the above-mentioned locations, and can display the wind speed and air volume of the roadway in real time. It is an important instrument for measuring the safety parameters of mine ventilation. Its sensor component is composed of wind speed sensor, wind direction sensor and sensor bracket.
principle
Principle of ultrasonic eddy joint measurement
The ultrasonic wind speed sensor uses the ultrasonic time difference method to measure the wind speed.
The speed of sound in the air is superimposed on the speed of the airflow in the wind direction. If the propagation direction of the ultrasonic wave is the same as the wind direction, its speed will be accelerated; on the contrary, if the ultrasonic wave propagation direction is opposite to the wind direction, its speed will be slowed down.
Therefore, under fixed detection conditions, the speed of ultrasonic propagation in the air can correspond to the wind speed function.
The precise wind speed and direction can be obtained by calculation. Since the speed of a sound wave is greatly affected by temperature as it travels in the air; this anemometer detects two opposite directions on two channels, so the effect of temperature on the speed of the sound wave is negligible.
Through the principle of differential pressure change
A fixed obstacle (orifice plate, nozzle, etc.) is placed in the flow direction, so that a pressure differential will be created depending on the flow rate. By measuring the differential pressure, it can be converted into a measurement of flow rate.
Principle of heat transfer
According to the Karman vortex street theory, an infinitely long nonlinear resistance body (ie, the vortex generating body C, the probe bar of the wind speed sensor) is vertically inserted into the infinite flow field. When the wind flows through the vortex generating body C, the On the downstream side of the edge of the vortex generating body, two rows of alternating and internally swirling vortex columns (ie, airflow vortices) will be generated, and the frequency f of the vortices is proportional to the flow velocity V, which is expressed by the formula as follows:
f=St V/d;
Therefore, the ultrasonic wind speed sensor uses the principle of ultrasonic vortex modulation to measure the vortex frequency.
