Error analysis of an intrinsic transient heat flux sensor

A distortion of the temperature response is introduced when a cavity is drilled into a slab to accommodate the thermocouple wire. The error due to the geometric disturbances as well as the different properties between the slab and the thermocouple is analyzed. It is found that unless the cavity hole is small, an appreciable error will be introduced in a steel slab with Alumel or Chromel thermocouple in the air-filled hole. Comparison between the case of constant heat flux and a case of time dependent one with its peak heat flux equal the constant heat flux shows that the error for the latter case may exceed the former case although the magnitude of the error is approximately the same. A guide for correcting the error is given.