Research on the Dynamic Calibration of Thermocouple and Temperature Excitation Signal Generation Method Based on Shock-Tube Theory

摘要

This paper introduces the equipment for generating an excitation signal during the process of thermocouple dynamic calibration in air medium, with the objective of dealing with the problems existing extensively in the excitation signal of incapable assessment of the rising time and inaccuracy in the traceability for the step amplitude. Based on the shock-tube theory, the step-temperature excitation signal that is suitable for the dynamic calibration of the thermocouple with appreciable rising time, wide-frequency bandwidth, and traceable step amplitude can be generated by means of the improvement in the structure of the traditional shock tube as well as the compensation of the shock-tube parameters. Through on-site assessment experimentation and dynamic modeling of the thermocouple, the time constant of the thermocouple can be obtained and the dynamic response of the thermocouple can be modified and compensated, the calibration result of which shows that the dynamic calibration method of the thermocouple proposed in this paper can be implemented for different ranges of frequencies and different phases of the temperature sensor with high reliability; moreover, the calibration equipment is miniaturized.