Methodology to Assess the Influence of Thermocouple Measurement Errors on Unsteady Heat Transfer Characteristics

In experiments related to high-temperature components of aero-engines, it is often necessary to investigate their characteristics under unsteady operating conditions. As a commonly used temperature measurement element, the accuracy of thermocouples under unsteady conditions determines the credibility of the experimental results. In this study, a numerical method based on the theory of one-dimensional unsteady heat conduction is used to investigate the influence mechanism of thermocouple temperature measurement error. The results show that the effects of environmental radiation, thermocouple mounting method, adhesive material, and convective heat transfer intensity on the measurement results need to be fully considered in unsteady experiments. Over the measured time period, the maximum measurement error caused by environmental radiation is 1.48 K; the maximum measurement error caused by different installation methods is 1.85 K. Furthermore, in the stage of the unsteady regular regime, the larger the thermal conductivity of the adhesive material, the smaller the resulting measurement error. When the heat transfer proceeds to 150s, the absolute measurement error is less than 0.5 K. In addition, the greater the intensity of convective heat transfer, the greater the measurement error in the initial stage of heat transfer. Convective heat transfer coefficients in the range of 50-250 W/(m 2 ·K) caused temperature measurement errors in the range of 0.2∼0.5 K.