Design Of Ultrasonic Guided Wave Temperature Sensor Based On Molybdenum Alloy

Temperature is one of the seven commonly used quantities in the international system of units.The measurement of temperature,especially the measurement of high temperature is very important in scientific research and development,industrial and agricultural production.At present,the existing temperature sensor,including thermocouple,thermal resistance,expansion thermometer and radiation thermometer,has become more and more mature in technology,which can meet the basic requirements of conventional applications.However,there are still some limitations,such as low detection accuracy,harsh environmental conditions for temperature measurement or clumsy equipment,long temperature measurement cycle.Ultrasonic guided wave temperature measurement is a new technology of temperature measurement,which has many advantages,such as wide measurement range,high sensitivity,fast response speed,strong anti-interference ability and so on.In this paper,based on the principle of ultrasonic guided wave temperature measurement,the ultrasonic guided wave temperature sensor of molybdenum-based alloy is designed,and the real-time and accurate distributed measurement of temperature is realized.In the aspect of theoretical research,the principle of ultrasonic guided wave temperature measurement is studied,combined with the design requirements,puts forward the design scheme of the molybdenum based alloy ultrasonic guided wave temperature sensor,and studies the key size parameters of the ultrasonic guided wave temperature sensor,and calculates the probe frequency and the waveguide rod diameter based on the dispersion theory.In the aspect of platform construction,according to the needs of the experiment,the experiment platform of ultrasonic guided wave temperature measurement is built,which is mainly composed of ultrasonic transducer,ultrasonic pulse generator receiver and oscilloscope.The algorithm of ultrasonic echo signal is proposed,including the mathematical model of ultrasonic characteristic echo signal.The cross-correlation method is used tocalculate the temperature characteristic information of ultrasonic signal,namely the delay time.Based on the ultrasonic temperature measuring platform,a distributed ultrasonic guided wave temperature sensor with waveguide material of molybdenum-based alloy was developed.The functional relationship between temperature and delay time of two sensitive elements of molybdenum base alloy at 17? ~ 1400? and 17? ~ 1500? was obtained by calibration experiments.The basic performance of distributed ultrasonic guided wave temperature sensor of molybdenum alloy was analyzed and tested,including repeatability of96.4% and 97%,resolution of 0.00025?s and 0.0007?s respectively,sensitivity of0.0027?s/? and 0.0074?s/? respectively.Finally,the measurement uncertainty of the sensor is studied,and the synthetic standard uncertainty is 10.4? and 8.4? respectively.In the 95 confidence interval,the extended uncertainty was 20.8? and 16.8?,respectively.