Research And Implementation Of Key Techniques For Ultrasonic Guided Wave Temperature Measurement

In the fields of industrial production,national defense and aerospace,high temperature measurement in harsh environments is the basis for solving many problems.At present,thermocouple temperature measurement and radiation thermometry are commonly used,but both have certain limitations.Due to the material performance limitation,the temperature response of the thermocouple is slow and the measurement range is narrow.In theory,the radiation temperature measurement method has no upper limit of temperature,but the measurement error is large due to the influence of object emission rate,measurement distance,smoke and fog.Ultrasonic guided wave temperature measurement is a new technique for temperature measurement using contact temperature measurement.It has many advantages such as wide range of measurement,high sensitivity,fast response speed and strong anti-interference ability.Based on the previous research of our research group,the thesis summarizes four key technologies that need to be considered in the ultrasonic guided wave temperature measurement.And to design the ultrasonic wave measuring system for four key technologies,it can be used to measure the temperature quickly and accurately.The four key techniques of ultrasonic guided wave measurement: first,Increase ultrasonic emission energy by optimizing ultrasonic emission circuit;second,the signal is band-pass filtered by a hardware circuit;third,the design of high speed and high precision dual channel digital acquisition system;fourth is to decouple the temperature information from the ultrasonic echo signal.Based on the principle of ultrasonic guided wave measurement and four key technologies,this paper designs a ultrasonic wave guide temperature measurement system for tungsten-bismuth alloy wire wave guide temperature sensors,including hardware system and temperature measurement software.The hardware system includes an ultrasonic transmitter circuit,a band-pass filter circuit,a voltage-controlled gain adjustment circuit,and adual-channel digital acquisition system.Dual-channel digital acquisition system takes FPGA as the core,including two A/D conversion circuits,D/A conversion circuit and USB module.The temperature measurement software uses LabVIEW as the development platform,which can realize the functions such as temperature parameter setting,command control,ultrasonic echo display,data storage,temperature measurement algorithm realization and temperature measurement result display.Finally,the ultrasonic guided wave temperature measurement algorithm is studied,and the temperature information decoupling algorithm is mainly studied.The calibration experiment was carried out for the temperature sensor of tungsten-rhenium alloy wire by the ultrasonic guided wave temperature measuring system,and the relationship between temperature and time delay was obtained.Through experimental measurement,the ultrasonic guided wave temperature measurement system designed in this paper has realized the four key technologies proposed,and can measure high temperature quickly and accurately.