Development Of Distributed Ultrasonic Guided Wave Temperature Measurement System

High temperature measurement occupies a very important position in aerospace,industry,energy,metallurgy and other fields.At this stage,the more mature temperature measurement methods in the industry mainly include thermocouples,infrared pyrometer and optical fiber temperature measurement.For high temperature and harsh environments such as chimneys,nuclear vitrification furnaces,and underground storage tanks that require multi-point temperature measurement,the above temperature measurement methods have certain limitations.For example,it is difficult for thermocouples to achieve multi-point temperature monitoring and online control in the furnace;infrared pyrometer are easily affected by smoke,fog,etc.;fiber-optic temperature measurement is rarely used in high-temperature scenarios,and the cost is high.Compared with the above temperature measurement methods,ultrasonic temperature measurement has strong environmental adaptability and flexible application scenarios,which can meet the needs of online control and distributed temperature measurement.Based on the principle of ultrasonic guided wave temperature measurement,this thesis designs an Fe-Cr-Al alloy ultrasonic guided wave distributed temperature sensor,and completes the system design through hardware development and software development.The system hardware development includes the design of ultrasonic transmitting circuit,ultrasonic receiving circuit,data acquisition circuit and power supply circuit.The system software development is based on Lab VIEW platform,including two functional interfaces of temperature measurement and time difference of arrival（TDOA）calibration,which can realize functions such as parameter control,echo signal display,distribution temperature value display,data storage,and TDOA calibration.Finally,in order to decouple the TDOA information from the ultrasound echo,the decoupling algorithm is analyzed,the TDOA is calculated by the cross-correlation method,and the TDOA is calibrated to obtain the TDOA-temperature characteristic curve.Combined with the hardware platform and the host computer system,the prototype integration of the distributed ultrasonic guided wave temperature measurement system is completed.The calibration experiment of 3 sensitive elements at a distance of 20 m from normal temperature to 900℃ was carried out on the prototype,and the performance indicators of the system were analyzed.Experiments show that the temperature measurement system designed in this thesis can realize remote segmented temperature measurement.