RANDOM CONVECTION UNDER CONDITIONS OF WEIGHTLESSNESS

Abstract

The nature of the transport process between a fluid and its enclosing surface is considered in the presence of random disturbances and, in particular, for conditions likely to prevail in space devices. The argument is developed that disturbances normally present in the motion of such devices may result in relatively effective transport mechanisms. On the basis of assumptions regarding the nature of the disturbances and their mode of occurrence, a number of circumstances are analyzed. The resulting transport rates generally are much greater than would be calculated for the process that would be expected in the absence of all disturbances. Nomenclature cp = specific heat F = arc/s2, the disturbance Fourier number Fo = O.T/X2 or ar/r2, Fourier number h = surface (or convection) coefficient hfg ~ latent heat of vaporization k = thermal conductivity m = mass rate of condensation/unit area n = positive integer in the probability distribution Nu = hs/k, Nusselt number, where k is the thermal conductivity of the fluid q = rate of heat transfer/unit area = amount of heat transferred Q = amount of heat transferred/unit area s = significant dimension t = temperature y = F/Fm Y = thickness of a condensate film a — thermal diffusivity 0 = temperature excess (t — t«>) p = fluid density T = time Subscripts