HEAT TRANSFER ENHANCEMENT IN MICROCHANNELS USING AN ELASTIC VORTEX GENERATOR

In this paper a novel heat transfer enhancement mechanism in the microchannel cooling passages with water as coolant is proposed and studied numerically. In this mechanism, an elastic vortex generator placed in the microchannel induces an oscillatory transverse vortex which is responsible for heat transfer enhancement along the channel. A two-dimensional incompressible viscous flow at moderate Reynolds numbers (100-500) in the laminar regime is considered. Due to the presence of the elastic vortex generator, the analysis becomes too complicated since the instantaneous nature of the fluid domain and the deformable elastic boundary requires solving a fluid structure interaction problem. To keep the problem from becoming too complicated, the numerical treatment in this study is two-dimensional. An arbitrary Lagrangian-Eulerian approach along with a structured grid is used to simulate the fluid structure interaction problem. It may be noted that the fluid structure interaction phenomenon often occurs as a destructive phenomenon in the engineering systems. However, in the present work it is regarded as a desired outcome. The results are compared with those of the simple channel (i.e., a channel without a vortex generator). For the Reynolds numbers within the tested range, 15-35% increase in the average Nusselt number as well as a 10-70% increase in the friction factor is observed. In addition, it is found that for all the Reynolds numbers tested, the elastic vortex generator gives a higher Colburn/friction factor ratio as compared with the rigid vortex generator.