Influence of temperature on the frequency response of fine-wire thermocouples over the range (300K-800K) in airflows

Theoretical and experimental investigation of the frequency response of fine-wire thermocouples is presented for the case of heated airflows (300K<T<800K) and for 0.5 m s -1 <U<8 m s -1 . The influence of temperature on the thermocouple transfer function has been studied through the variation of physical properties of surrounding gas and thermocouple material. Dynamic calibration has been carried out by using an 'external heating technique'. This study provides evidence that, over the velocity and temperature ranges considered, the transfer function depends on thermocouple geometry (r w and r b /r w ) as well as on characteristics of the flow (velocity and temperature).