A NUMERICAL INVESTIGATION OF HEAT TRANSFER ENHANCEMENT FOR ELECTRONIC DEVICES USING AN OSCILLATING VORTEX GENERATOR

Abstract

In this article, a new concept of vortex generator is proposed to enhance the heat transfer of electronic devices. An oscillating bar is set in a channel with heated obstacles. The oscillating bar serves as an oscillating vortex generator to actively generate vortices. The behavior of the oscillating bar and flow is coupled, and the variations of the flow and thermal fields are classified into a type of moving boundary problem. An arbitrary Lagrangian-Eulerian kinematic description method is employed to describe the flow and thermal fields, and a Galerkin finite element method is used to solve the governing equations. The effects of Reynolds number, oscillating speed, and oscillating amplitude of the bar on the flow and heat transfer are examined in detail. The results indicate that vortices induced by the oscillating bar are actively and largely formed around the channel and migrate downstream. As the bar moves upward, the vortices around the top wall of the channel push the low-temperature and high-speed core flow toward the top surfaces of heated obstacles and induce the vortices within the grooves to eject into the core flow. These flows assist the heat transfer from heated obstacles. As the bar moves downward, the vortices around the top wall of the channel push the core flow toward the grooves and induce new vortices to form around the top surfaces of the heated obstacles. These flows may prevent the heat transfer from the heated obstacles. In addition, the heat transfer rate increases when the oscillating amplitude of the bar is increased, but it is not directly proportional to the oscillating speed of the bar. The overall heat transfer from heated obstacles is augmented greatly.