| At present,in the field of ultra-high temperature testing,there are difficulties in in-situ testing of high-temperature temperature fields in harsh environments.Among the known temperature measurement methods,the thermocouple temperature measurement method is a single point measurement that requires temperature compensation and cannot achieve multi-point temperature monitoring for a long time;The radiation temperature measurement method adopts a non-contact temperature measurement method,which can reach the upper limit of temperature measurement above 3000 ℃ without being affected by other factors.However,in practical applications,the temperature measurement data is affected by the airflow and smoke in the measured field,resulting in excessive errors.As a new contact temperature measurement method,ultrasonic guided wave temperature measurement has high measurement accuracy,wide range,and is not easily affected by other factors.By selecting specific waveguide materials,sensitive structures,waveguide sizes,its temperature measurement range,response speed,anti-interference ability,and other indicators can be further optimized.Therefore,based on the preliminary research of the project,this article conducts research on ultrasonic guided wave temperature measurement technology for single crystal oxide materials in oxidation environments.The main research content of this article is as follows:Based on single crystal oxide materials,this paper analyzes the transmission mechanism of ultrasonic guided waves in single crystal oxide materials,and studies the relationship between ultrasonic transmission characteristics of single crystal oxide materials and temperature;Selecting single crystal sapphire and magnesium aluminum spinel as waveguide rod materials,using the principle of ultrasonic temperature measurement,design a temperature measurement scheme;The influence of the relationship between the crosssectional diameter of the research area and the diameter of the waveguide rod on the ultrasonic echo signal is studied.The sensitive size parameters of the single crystal oxide waveguide rod are designed,and the preparation of the single crystal oxide waveguide rod sensor is completed.Build an ultrasonic temperature measurement system consisting of a single crystal oxide ultrasonic guide rod,ultrasonic pulse excitation device,data acquisition and display device,etc.Complete the selection of transducers,ultrasonic excitation and reception circuits,data acquisition and software design,achieve 40 MHz data acquisition,and 25 ns signal resolution.Optimize the decoupling algorithm for ultrasonic temperature measurement,introduce the current temperature decoupling algorithm for ultrasonic temperature measurement data,analyze the existing problems,propose a deep learning based ultrasonic feature signal recognition network model,and conduct ultrasonic temperature measurement testing,with a temperature measurement upper limit of 1800 ℃.The accuracy of the ultrasonic feature signal recognition network model is 0.993,m AP@0.5 is 0.990,m AP@0.5 0.95 is 0.796.Establish an ultrasonic temperature measurement environment,complete calibration experiments on sapphire and magnesium aluminum spinel for ultrasonic temperature measurement,analyze ultrasonic temperature measurement data,and evaluate sensor performance.The results show that the sensitivity of single crystal sapphire and magnesium aluminum spinel waveguide rods is 0.43m·s/℃ and 0.50 m·s/℃,respectively.Single crystal sapphire has faster sound velocity and lower temperature sensitivity compared to magnesium aluminum spinel.In summary,this article has completed the research on single crystal oxide ultrasonic guided wave temperature measurement,achieving temperature calibration with an upper limit of 1800 ℃,providing theoretical reference for temperature measurement in ultra-high temperature environments,and has important significance in aerospace applications. |
