Ultrasonic Wind Speed Measurement System For Mining

China’s coal resources are abundant,but there are many unsafe factors in coal mining,especially gas explosion and dust inhalation seriously threaten the lives of underground personnel,mine ventilation is one of the main technical means to ensure mine safety,and accurate wind speed measurement is of great significance to achieve mine ventilation.For the current mining wind measurement equipment has poor accuracy,easy to wear,can not measure the average wind speed and other problems,ultrasonic wind measurement method without mechanical wear,high accuracy,can measure the average wind speed,more suitable for mine tunnel wind speed wind volume monitoring,and the relevant content of the thesis are summarized as follows:(1)The theory of ultrasonic wind speed measurement in mine tunnels is analyzed.The essence and characteristics of ultrasonic waves are summarized,the principle and structure of the ultrasonic wave transducer are explored,the influence of the way the transducer is set up in the mine tunnel on the ultrasonic wave signal propagation is analyzed,the time difference method is selected as the measurement method after comparing various wind measurement techniques,and the wind speed measurement formula is derived,the key to which is the accurate measurement of ultrasonic wave flight time.(2)The analysis and simulation of ultrasonic time-of-flight algorithm are carried out.The factors affecting the flight time of the threshold method are analyzed,and for the problem that the fixed threshold method is susceptible to signal amplitude changes,an adaptive five-point threshold flight time algorithm is proposed,which overcomes the influence of echo signal amplitude changes on the measurement accuracy and has good real-time performance.In order to obtain more accurate flight time,the interpolation function method is used to obtain the continuous output flight time,and more accurate wind speed value is calculated.(3)The ultrasonic wind speed measurement system for mining is designed.The hardware part uses STM32 as the core controller of the system,and designs the driver circuit,receiver filter amplifier circuit,power supply circuit and communication circuit.The software part includes the main program,driver transmitter program,acquisition program and algorithm processing program.Debugging hardware and software together control the transducer to achieve the function of ultrasonic emission,receiving acquisition and wind speed measurement.(4)An ultrasonic wind speed test platform is built.Test and analysis of the prototype in the wind tunnel,test results show that the system in the 0 ～ 12.5m/s wind speed range of measurement accuracy of 0.1m/s,the maximum relative error of 2.75%,effectively improve the accuracy of the average wind speed measurement in the mine tunnel.In this thesis,a mining ultrasonic wind speed measurement system is developed and designed to meet the demand for accurate wind measurement in underground coal mines,with high measurement accuracy and good stability,which can achieve accurate measurement of the average wind speed in mine tunnels,meet the demand for engineering applications,greatly improve the efficiency and safety of mine ventilation systems,and have broad application prospects.