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国外有关测量高温气流温度的动态热偶法的文献,都是以简化的热平衡关系式(1)作为推算方法的基础。本文根据更一般的热平衡关系式(3),并以我们的具体实验条件为例,对这些文献中采用的推算方法的方法误差作了系统的分析。分析结果表明,只要热电偶丝伸出保护瓷管的长度足够长,且是的对焊热偶,则导热误差可以忽略不计;辐射可以引起一定的误差;但主要的方法误差却来自于热惯性系数T随丝温的变化,而材料比热随温度的变化又是引起T变化的主要原因。根据分析结果,文中推荐以方程(10)或(12)作为建立镍铬-镍铝对焊热偶新推算方法的基础,并对进一步的改进工作提出了某些建议。
Foreign literature on the dynamic thermocouple method for measuring the temperature of high-temperature air flow is based on a simplified thermal equilibrium equation (1) as a method of estimation. Based on the more general thermal equilibrium relation (3) and taking our specific experimental conditions as an example, this paper systematically analyzes the methodological errors of the estimation methods adopted in these literatures. The results show that the thermal error can be neglected as long as the length of the thermocouple wire extending beyond the length of the protective ceramic tube is a butt-welded thermocouple. Radiation can cause some error; however, the main method error is from the thermal inertia Coefficient T changes with the silk temperature, and material specific heat with temperature changes is the main reason causing T changes. Based on the results of the analysis, we recommend Equation (10) or (12) as the basis for the new calculation method of Ni-Cr-Ni-Al butt welding thermocouples and some suggestions for further improvement.