Design And Experimental Study Of High Temperature Ultrasonic Temperature Measuring Transducer

With the rapid development of aerospace industry,there are more and more demands for non-destructive measurement of internal temperature field of solid structure in high temperature environment,and the accuracy requirements are higher and higher.At present,the contact and single point measurement methods are usually used,such as thermocouple and thermal resistance.They need to drill holes in the structure and embed temperature measuring elements,which directly leads to structural damage,It also affects the accuracy of temperature measurement,and can not realize the real-time measurement of temperature field.In this paper,the method of measuring the internal temperature field of solid structure by electromagnetic ultrasonic is proposed.The principle of measurement is to excite and receive the ultrasonic through the electromagnetic ultrasonic transducer.According to the correlation between the propagation speed of ultrasonic in the medium and the temperature,the temperature of the medium is obtained.The electromagnetic ultrasonic transducer is the core component,which determines the range and accuracy of ultrasonic temperature measurement,Therefore,it is necessary to design and study the high temperature ultrasonic temperature measurement transducer.In this paper,the ultrasonic temperature measurement technology in high temperature solid structure is studied.The methods of theoretical analysis,numerical simulation and experimental verification are adopted.The research is carried out from the theoretical research of electromagnetic ultrasonic multi field coupling analysis method,the design and optimization of high temperature resistant ultrasonic transducer,and the experimental research of high temperature resistance of ultrasonic transducer,The non-destructive testing methods and means of internal temperature field of high temperature structure are explored.Firstly,from the point of view of physical field coupling,the multi field coupling analysis method of electromagnetic ultrasonic transducer in solid structure is studied,and the mathematical model and boundary conditions of each physical field in the process of energy transfer are established.A two-dimensional finite element model is established according to the structural parameters of the existing ultrasonic temperature measuring transducer,and the propagation characteristics of the ultrasonic wave are obtained by using COMSOL software.The effectiveness of the coupling analysis method is verified by experiments,which lays a theoretical foundation for the optimal design of the transducer.Secondly,the coil structure is the key factor affecting the directivity of the ultrasonic transducer.In order to improve the directivity of the ultrasonic field,the coil structure of the existing transducer model is optimized,and the propagation characteristics of the ultrasonic excited by the modified model are calculated and analyzed.The main parameters that affect the performance of the transducer are analyzed theoretically.The numerical simulation of these parameters is carried out,and the influence law of these parameters is obtained.The key parameters are selected,and the orthogonal test method is used to obtain the optimal combination of the transducer parameters,which provides the basis for the design of the transducer;In order to achieve the high temperature resistance of the transducer,the high temperature resistance of the material and the structure design are studied.Finally,from the point of view of experimental verification,the high temperature test of ultrasonic transducer is carried out.Firstly,the feasibility of high temperature resistance of the transducer is verified.The results show that the performance of the transducer is stable in the test temperature range,and it can receive clear echo signal with high signal-to-noise ratio.The correlation between wave velocity and temperature is the premise and foundation of ultrasonic solid temperature measurement.The temperature sensitivity of ultrasonic sound in ultrasonic solid temperature measurement is analyzed theoretically,and the experimental platform of ultrasonic solid temperature measurement based on sound time measurement is built,The results show that the wave velocity and temperature correlation data obtained based on the temperature measurement platform have high repeatability,good linearity and reliable function relationship.The research shows that the high temperature ultrasonic temperature measurement transducer designed in this paper can meet the requirements of nondestructive measurement of internal temperature field of solid structure at high temperature(600 ℃),and the measurement accuracy can reach 1 ℃,which provides a technical means for real-time nondestructive detection of internal temperature field of high temperature solid structure.