Investigation of Heat Transfer and Fluid Mechanics across a Heated Rotating Circular Cylinder in Crossflow

摘要

Considerable attention has been given to flows passing over bluff bodies such as cylinders. This is due to their importance in applications such as heat exchanger, cooling towers and electronic circuit cooling. It has been proved that flow performance and heat transfer could be improved remarkably if the cylinders rotate and flow stabilizers/blockers are used to increase residence time and Nusselt number. This is due to the effect of the vortical structures in the wake region on the drag and heat transfer coefficients. Therefore, forced convection heat transfer across stationary and rotating horizontal cylinder dissipating uniform heat flux was investigated numerically and experimentally in this work. The maximum values of rotational and crossflow Reynolds numbers attained were 960 and 160, respectively. The non-dimensional rotational velocity (a) was varied from 0 to 6. Finite volume numerical simulations using ANSYS were performed. Average temperatures of the cylinder surface were measured by using a thermal camera and the flow profile was captured by High Speed Photography and LDV, offering new experimental results for correlation purposes. Results show that the maximum average heat transfer rate occurs at the same Reynolds number whilst the minimum value occurs at the higher rotational Reynolds number. At higher rotational Reynolds numbers the Nusselt number is nearly independent of Reynolds number and thermal boundary conditions. Comparison with previous numerical studies showed good agreement.