Experimental Investigation of a Thermal Plume’s Air Entrainment in a Circular Cone

Authors: Ahmedou M. Mahmoud, Z.Yahya

Volume 8, Issue 4, Paper No. 080403


  In this study, we experimentally determined the effects of conical walls with low opening angles on a thermal plume’s air entrainment. We first studied the development of a thermal plume placed at a specific height from the floor to ensure regular lateral and vertical air entrainment to a heat source. An analysis of the results showed the presence of two zones along the plume’s height. The same plume source was then placed at the inlet of a vertical cone open at its extremities, which ensured purely vertical air entrainment. The convective transfer along the cone’s walls as a function of the opening angles was studied to determine the critical angle ( from at which the flow’s thermal and dynamic characteristics began to improve. The resulting flow structure was divided into three distinct zones during its vertical development. The comparative study revealed that the cone walls radially widened the thermal plume and created a low recirculation region around the axis above the heat source. Due to the conical walls’ effects, the relative increases in the plume width, mass flow rate, and convective heat flux in the plume were 20%, 25%, and 57%, respectively. The two configurations ‘air entrainment coefficient increased by approximately 28% in the plume that developed inside the cone.

Keywords: Air entrainment mode; Air entrainment coefficient Thermal plume;  Natural convection flow; Flow inside circular cone


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