Research On Thermocouple Dynamic Testing System Based On Impulse Response

As the technology of China’s high-end equipment manufacturing continues to progress,the environment in which the sensors are located becomes more and more complex,and the performance requirements of the sensors are increasingly high,especially in the hightemperature transient environment,the temperature sensor dynamic characteristics of the requirements are more demanding.Thermocouples are extensively applied in high temperature extreme environments with high reliability and wide range.However,their thermal inertia can lead to temperature measurement delays,which can affect the accuracy of measurement results.Therefore,an in-depth investigation of the dynamic performance of thermocouples is a key aspect to ensure that they meet engineering applications.In this paper,the S-type thermocouple is used as the research object,and the pulse signal excitation is used to realize the test of thermocouple response time constant.The main work of this thesis is as follows:Firstly,a three-dimensional model of S-type thermocouple was constructed in the finite element simulation software.The pulse function and Gaussian function interface were used together to constitute the pulse laser load applied on the surface of thermocouple thermal junction,and the influence of pulse laser parameters and structure size of thermocouple thermal junction on the dynamic characteristics of the thermocouple was explored.Secondly,the uncertainty between the laser parameters and the thermocouple surface temperature relationship during the thermocouple dynamic response test is addressed.In this paper,an error back propagation neural network is optimized based on genetic algorithm to design a laser output temperature rise prediction model.The BP neural network is verified to be superior to the GA-BP network model by comparing it with the optimized model.The model provides temperature rise prediction for subsequent dynamic testing of thermocouples,avoids thermal damage to the sensor due to improper parameter selection during testing,and provides an idea for laser output temperature control research.Finally,the dynamic response test platform of the thermocouple based on the pulsed laser is designed and built.Using the pulsed laser as the external excitation,an innovative proposal is made to regulate the laser signal by combining a signal generator and an amplifier to perform real-time adjustment of the laser multi-parameters as needed.Combined with the previous research work,suitable laser parameters are selected and the prepared thermocouple is dynamically tested using the constructed test platform to verify the effects of thermal junction area and thermal junction thickness on the response time constants of the thermocouple.