Natural Convection Effect on Transient Short-Hot-Wire Method

抄録

Natural convection effect on transient short-hot-wire method is studied experimentally, by comparing the wire temperature variations obtained for various liquids under normal gravity with those under microgravity conditions. The critical time corresponding to the onset of natural convection effect is determined and non-dimensionalized as the critical Fourier number Foe. A correlation equation for Foe is proposed as functions of Rayleigh number Ra and aspect ratio L. The equation is found to agree well with the previous results obtained for the cases of large aspect ratio. It can be used generally to estimate the critical times for various cases of transient hot-wire method which is widely used to measure the thermal conductivity and thermal diffusivity of fluids.