Design of high precision mine ultrasonic anemometer

The minimum measured wind speed of the existing anemometer can not meet the requirements of precise wind measurement under the condition of low wind speed in mines. In order to solve this problem, based on the principle of ultrasonic time difference method wind speed measurement, a high-precision mine ultrasonic anemometer with low starting wind speed is designed. Two ultrasonic transmitting probes and two ultrasonic receiving probes are arranged alternately to form two ultrasonic propagation paths. The downwind and upwind propagation times of ultrasonic waves in a specific wind speed field are measured respectively, and the average wind speed between the transmitting probes and the receiving probes is solved by using the superposition effect of the propagation speed of ultrasonic waves in the air and the wind speed (the effect of temperature on the wind speed measurement can be ignored). In order to analyze the effect of ultrasonic probe direction on the accuracy and reliability of measurement, four different probe arrangement modes are used to carry out the experiment. The results show that the more serious the ultrasonic probe direction dislocation is, the larger the standard deviation and fluctuation range of wind speed. Therefore, the infrared orientation device is used to calibrate the installation position of the anemometer to reduce the measurement error caused by the ultrasonic probe direction dislocation. The moving average method is used to smooth the original wind speed waveform curve to eliminate random noise and improve the stability of output wind speed. By analyzing the factors affecting measurement precision, it is determined that the ultrasonic emission frequency is 40 kHz and the standby time is 100 ms. The theoretical calculation and experimental results show that the resolution of the anemometer is 0.01 m/s, the measurement error is ±0.1 m/s, and the starting wind speed is lower than 0.1 m/s, which can meet the precise wind measurement requirements of the mine roadway with low wind speed.