Ultrasonic wind speed sensor is a fully digital signal detection instrument, can be calculated through the ultrasonic propagation time in the air wind speed, is widely used in mines, forests, weather monitoring and other fields. Today, I will briefly introduce the ultrasonic wind speed sensor.
Ultrasonic wind speed sensor is mainly the use of ultrasonic time difference method to realize the measurement of wind speed, the sound propagation speed in the air, and the wind direction will be superimposed on the air velocity. If the propagation direction of the ultrasonic wave is the same as the wind direction, its speed will be accelerated; conversely, its speed will be slowed down. Therefore, under the fixed detection conditions, the ultrasonic propagation speed in the air can be corresponded to the wind speed function through the calculation of the precise wind speed and wind direction can be obtained.
After the principle of pressure difference change
A fixed obstacle (orifice plate, nozzle, etc.) is set up in the active direction so that a pressure difference occurs depending on the flow rate. The measurement of differential pressure can be converted into the measurement of flow rate.
Heat transfer principle
According to Karman vortex street theory (see Figure 1), in the infinite boundary flow field straight into an infinite length of nonlinear resistance body (i.e., vortex onset of body C, wind speed sensor probe crossbar), medicine wind flow through the vortex onset of the body C, in the vortex onset of the body edge of the downstream side of the vortex will be the onset of the two rows of alternating, inwardly swirling vortex columns (i.e., the airflow vortices), and vortex onset of the frequency of f is compared to the flow rate of V, the formula shows the following.
f=StV/d.
With the above formula we can also draw the following conclusions when the wind speed sensor and the transducer set up between a blocking body, when the flow of air through the blocking body, underneath the two columns of vortices produced by the internal rotation of alternating vortices, due to the vortex on the ultrasonic blocking effect of the ultrasonic wave, ultrasonic transducer will receive the ultrasonic intensity with the frequency of changes in the vortex when the vortex does not block the ultrasonic wave, the ultrasonic intensity of the maximum;; the ultrasonic intensity is the largest; when the vortex exactly block the ultrasonic wave, the ultrasonic intensity is the largest. When the vortex exactly block the ultrasonic wave, the received ultrasonic wave intensity is minimum. Ultrasonic transducer will receive the frequency signal into the frequency/electrical repulsion conversion module, converted to voltage, the two into a linear proportional relationship, that is, the voltage and wind speed into a linear proportional relationship. Therefore, ultrasonic wind speed sensor is the use of ultrasonic vortex modulation principle to determine the vortex frequency.
Summarize the above can be seen in many places ultrasonic wind speed sensor to bring people not only data, but also a safe and secure, and the traditional method of wind speed, wind volume measurement, there is often a lack of accuracy, cost is too high, poor stability and other issues.