Date of Award

2012

Degree Type

Thesis

Department

Mechanical Engineering

First Advisor

Ibrahim, Mounir

Subject Headings

Computational fluid dynamics, Heat -- Transmission

Abstract

Three-dimensional Computational Fluid Dynamics (CFD) models were developed to simulate fluid flow and heat transfer in a variety of helical channel geometries: circular and elliptical. Laminar flow was observed for Reynolds number between 200 and 1000. Code validation was done for developing steady laminar flow in a circular curved channel. The CFD results were compared to previous numerical results to verify that the model was producing valid results. The curve of the channel has a centrifugal effect on the fluid flow creating secondary flow known as Dean cells. This secondary flow moves the location of the maximum axial velocity towards the outer wall of the channel and alters the developing temperature profiles as well. The helical models were designed to assess if the effect of the curve increases the rate of heat transfer when a constant surface temperature is applied to the wall of the channel. Different channel geometries were used to determine the effects on fluid flow and heat transfer in a helical channel. A channel with a 180° turn was also modeled in two different ways. One with a rounded 180° curve and the other with three perpendicular channels joined together to create a square 180° turn. The three combined channels are typically easier and less expensive to manufacture, but the fluid flow and heat transfer properties need to be considered before selecting the design. The helical models produce similar results. The Dean vortices produced in the secondary flow within the fluid aids in the heat transfer properties of the fluid. Of all the helical cases, a horizontal ellipse cross section achieved the highest outlet-inlet temperature difference, especially for higher Reynolds numbers. Even though the horizontal elliptical helix model produced the highest temperature difference, the circular helix model produced the highest percent increase over its straight model. Using a figure of merit to compare the Nusselt numbers and friction factors for each case, the circular helix geometry prov

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