| Thin-film thermocouple is a new type of temperature sensor.It is widely used in temperature detection in aerospace,munitions and chemical fields because of its fast response,high measurement accuracy,and small impact on the measured environment,especially for aero-engine turbines.Temperature measurement of high-temperature key parts such as blades,combustion inner walls,and gun chambers.Thin film thermocouples need to be verified and calibrated in the process of development and use to obtain the relationship between temperature and potential,so as to ensure their measurement accuracy.Most of the verification and calibration equipment in china and abroad are built by scientific researchers according to their needs,and there are problems such as poor temperature field uniformity,large temperature fluctuation,and low reliability,which lead to low reliability of the verification results of thinfilm thermocouples.In order to successfully complete the verification and calibration of thinfilm thermocouples,a verification and calibration device is designed in this paper,and a shorttype multi-zone high-temperature furnace and a reference thermostat specially designed for thin-film thermocouples are designed.Nanovolt and micro-ohm thermometers are selected as the data acquisition equipment.The device can complete the verification and calibration of sheet-like thin-film thermocouples whose size is less than or equal to 150mm*35mm.The main research contents of this paper are as follows:（1）The verification and calibration device of thin-film thermocouple for aviation is designed.According to the working principle of thin-film thermocouple verification and calibration and the basic laws of heat transfer,a short multi-zone high-temperature furnace and a reference end thermostat are designed,and the structure and working principle of the whole machine are described in detail.Research and design of key components such as circulation system and furnace drum.（2）The temperature field simulation analysis of key components is carried out.The simulation model of the reference end thermostat working area and the multi-zone high temperature furnace tube was established,the heat transfer process of the model was analyzed,and the Fluent software was used for simulation.The distribution of the temperature field in the working area of the thermostat at the reference end was analyzed,and the material of the working area and the arrangement of the insulation cotton were determined.Zone length and heating power.（3）The temperature field test experiment of the multi-zone high temperature furnace and the reference end thermostat was carried out.A detailed test plan was designed,and a high temperature furnace axial temperature field test platform and a reference end thermostat temperature field stability test platform were built.The test results show that the performance of the multi-zone high-temperature furnace is better than that of the ordinary single-zone hightemperature furnace.The length of the uniform temperature field can reach 80 mm,and the axial temperature gradient is less than or equal to 0.4℃/10 mm required by the national regulations.The temperature fluctuations were kept within the range of 0.25°C/10 min.（4）The fitting of thermoelectric characteristic curves of thin film thermocouples based on the least squares fitting principle is studied.A thin-film thermocouple test platform was built by using a multi-zone high-temperature furnace,a reference end thermostat and other devices.The calibration test was carried out on the In2O3/Zn O-based thin-film thermocouple and the test data were recorded.The test data was used on the basis of the least squares method.The curve fitting analysis of the thermoelectric characteristics of the thin film thermocouple was carried out,and it was concluded that the fitting effect of the second-order polynomial fitted by five temperature points was the best. |
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