An Experimental Study of Natural Convection From an Array of Heated Protrusions on a Vertical Surface in Water

Abstract

An experimental study of steady state and transient natural convection from a single column of eight heated, rectangular protrusions mounted on a vertical surface in water is presented. The component power dissipation levels were varied in the range 0.2–1.5 W using foil heaters attached to the base of each protrusion. Visualizations in three different vertical planes indicated a three-dimensional, laminar developing boundary region type flow structure away from the protrusions. Near the vertical surface, the fluid followed the protrusion boundaries with no evidence of vortex formation. Surface temperatures were measured at the centers of each of the five fluid exposed faces. Nondimensional heat transfer rates were calculated based on these measurements. Accounting for the increasing convected energy downstream resulted in a single correlation for all components and power levels. Temperature measurements in the adjacent fluid were made using a movable hypodermic probe. Transport evolution during the transient showed initially diffusive patterns, followed by rapid development of entrainment.