Role of a Single Shield in Thermocouple Measurements in Hot Air Flow

To investigate the role of a single shield on steady temperature measurement using therrnocouples in hot air flow, a methodology for solving convection, conduction, and radiation in one single model is provided. In order to compare with the experimental results, a cylindrical computational domain is established, which is the same size with the hot calibration wind-tannel. In the computational domain, two kinds of thermocouples, the bare-bead and the single-shielded thermocouples, are simulated respectively. Surface temperature distribution and the tempera- ture measurement bias of the two typical thermocouples are compared. The simulation results indicate that： 1） The existence of the shield reduces bead surface heat flux and changes the direction of wires inner heat conduction in a colder surrounding; 2） The existence of the shield reduces the temperature measurement bias both by improving bead surface temperature and by reducing surface temperature gradient; 3） The shield effectively reduces the effect of the ambient temperature on the temperature measurement bias; 4） The shield effectively reduces the influence of airflow velocity on the temperature measurement bias.