Errors in steady heat transfer experiments increase if it is measured before steady state

and the half-life period of errors of average Nusselt number is about 2500~2700s in general conditions. In order to modify the state of heat transfer experiments

rotating disk cavity heat transfer experiments were performed by transient numerical simulation. Results presented showed that it was a long time before steady state in heat transfer experiment of cavity. An approach of predicting steady time and allowable measurement time was developed by permissive errors of experiments

and allowable measurement time can be pre-calculated before experiments by Fourier number. Its also suggested that the sensors be observed per minutes by regularity of logarithm until the numbers of sensors are constant

then the experiment is in steady state.