HEAT-TRANSFER CHARACTERISTICS OF A CONSTANT HEAT-FLUX VERTICAL PLATE IN WATER

Experimental examination of the heat transfer characteristics of a ver tical plate in water is presented. Results are given as the variation of local Nusselt number with Rayleigh number for different heat fluxes . The experiments included temperature measurements and flow visualiza tion by the use of the simple and precise method of electrochemical fo rmation of dye technique. Arrangements were made so that color changes occurred both at the surface of the vertical plate and within the bou ndary layer. The free convection heat transfer in water, as expressed by the power-law relationship between the Nusselt number and Rayleigh number, Nu = 0.89 Ra-0.2, is shown to be adequate for the range of Ray leigh numbers 10(4) < Ra < 10(13) for a constant heat flux boundary co ndition. There appear to be similarities in the mechanisms of transiti on from laminar to turbulent boundary layer flow between those for nat ural convection and those for the Blasius-type forced flow over a flat plate. The Emmons spot source band for natural convection flow is lar ge when compared to the narrow band for Blasius flow.