Gas temperature measurements using fibre Bragg grating during fire experiments in a tunnel

Gas temperature measurements with thermocouples are affected by radiation. This effect means that the temperature measured by a thermocouple can be far from the actual gas temperature. To study this effect and to compare the thermocouple readings with the readings of a fibre Bragg grating (FBG) sensor, fire experiments were performed in a model-scale tunnel. In this paper the results from two such fire experiments are presented. The temperatures measured using thermocouples with different diameters and the FBG sensor are compared and discussed. The “true” gas temperature, corrected for radiation effects from the thermocouples, was calculated from the results from the thermocouples with different diameters. The results show that the temperature measured by the FBG sensor is closer to the “true” gas temperature than is the case for any of the thermocouples used in these tests.