Study On Extrapolation Method Based On Sapphire Fiber Blackbody Cavity Temperature Sensor

Temperature is a very important parameter in scientific research and production. In the fields of aviation, aerospace engines and nuclear and chemical explosives test, many cases the transient high temperatures to be measured are large amplitude and rapid changes in temperature. Sometimes temperature measurement condition is very poor, which is a challenge for technology. Especially the cost is very high in many situations, so the reliability and the data capture rate of the system are demanded highly. There is not a nature technology for temperature measurement under these special circumstances.Sapphire fiber blackbody sensor based on Planck's radiation law is the most effective way in temperature measurement. However, the tiptop of temperature sensor base on the melting point of Sapphire. In order to broaden the scope of transient temperature measurement, it must have a corresponding testing theory and technology. Extrapolation method is designed to solving this problem. By extrapolation methods, the surface temperature can be get as long as the detector recording the lower and slow-changes temperature of Blackbody Cavity internal. The extrapolation model which describes the transient heat transfer in blackbody cavity is established after analyzing the heat transfer law of blackbody cavity. Analysis method, separation of variables and finite-difference are used to solve the extrapolation model. Then analyze and compare the three methods in the aspects of ease of solving, feasibility and accuracy, etc.After the extrapolation model of Blackbody Cavity is accomplished, the reliability and accuracy of the model are priorities. The quality can be evaluated through two ways. First, make experiments in the laboratory. Compare the result of extrapolation with the actual surface temperature of blackbody cavity to analyze the reliability of the model. Then, use the ANSYS finite element analysis software on the computer to simulate the transient heat transfer process of blackbody cavity. Estimate the accuracy of the model by comparing the coherence of these two aspects. In this paper, the extrapolation result and the result of infrared thermometer measured are in line. At the same time, this point is proved by ANSYS simulation result.