Research On Key Technologies Of Sapphire Ultrasonic Temperature Sensor

With the development of modern society,the accurate detection and control of temperature plays an important role in aerospace,materials,chemicals,and energy.Nowadays,in many environments,past contact-type temperature detection methods have been difficult to meet people's need for high-temperature environment measurement,the non-contact temperature measurement method is limited in its application due to its complex principle and large impact on environmental factors,high cost,and so on.Ultrasonic temperature measurement method is not easy to be interfered with,has a wide range of temperature measurement and other advantages,it can well supplement and improve the previous temperature measurement methods,and has great potential for development in the field of temperature testing in the future.Therefore,based on the theory of ultrasonic temperature measurement,a sapphire ultrasonic temperature sensor is designed to measure the temperature under high temperature environment.In this paper,the causes of guided waves are explained,the ultrasonic guided wave group velocity,phase velocity,dispersion and multi-mode characteristics are analyzed.Using the GUIGUW software to study the dispersion characteristics of the sapphire waveguide rod theoretically,it is found that the L(0,1)guided wave with single excitation mode and weak dispersion can be distinguished from the guided wave of other modes,it is easy to analyze the signal.Then,according to the principle of ultrasonic temperature measurement,two temperature measurement methods are proposed,one is to directly measure the sound velocity in the measured medium to measure the temperature,and the other is to measure the temperature by measuring the sound velocity in the material that is in thermal equilibrium with the measured medium.This article selects the second way to measure temperature and uses sapphire as the acoustic waveguide material.Secondly,the main components of the ultrasonic temperature sensor were introduced,especially the design of the sapphire waveguide to enhance the extraction of the reflected waveform.Finally,using ANSYS finite element software to simulate the ultrasonic transmission characteristics in the sapphire waveguide rod,and using the sapphire ultrasonic temperature sensor for temperature measurement experiments,the curve of the sound velocity with temperature was obtained.By observing the ultrasonic transmission characteristics of the ANSYS simulat ion results and ultrasonic temperature experiment results,it is found that the time difference between the reflection signal of the groove and the end face is elongated as the temperature rises,that is,the sound velocity of the ultrasonic wave decreases with increasing temperature in the sapphire waveguide rod,and From the relationship between the sound speed and temperature obtained,the two have a good linear relationship,which further validates the feasibility of ultrasonic temperature measurement and is of great significance to the development of ultrasonic temperature measurement technology in the future.