A Numerical Study of the Effect of Longitudinal Vortex Generators on Heat Transfer Enhancement and Pressure Drop in a Rectangular Channel 2018-01-0782

Longitudinal vortex generation is a common technique for enhancing heat transfer performance. It can be achieved by employing small flow manipulators, known as vortex generators (VGs), which are placed on the heat-transfer surface. The vortex generators can generate longitudinal vortices, which strongly disturb the flow structure, and have a significant influence on the velocity and temperature distributions, causing improved thermal transport.

In this work, numerical simulations are conducted for a horizontal rectangular channel with and without a pair of longitudinal vortex generators. The vortex generators are fitted vertically on the bottom surface of the channel. The Computational Fluid Dynamics (CFD) analysis aims to acquire a better understanding of the flow structure and heat transfer mechanisms induced by longitudinal vortex generation. The simulation is performed using ANSYS Fluent, and three flow inlet velocities are considered: 1.38 m/s, 1.18 m/s, 0.98 m/s. Flow through a plain channel (baseline) is simulated first and following that, flow characteristics induced by vortex generators are analyzed. Three different attack angles are tested (15 degrees, 30 degrees, and 45 degrees) to evaluate the impact. It is seen that the existence of vortex generators significantly enhanced the heat transfer performance, which is also accompanied by bigger pressure loss across the channel. Out of the three attack angles, the 45 degree showed the highest augmentation in heat transfer. The averaged heat transfer coefficient increased 102%, 112%, and 121% under different flow entry velocities of 0.98 m/s, 1.18 m/s, and 1.38 m/s. At the same time, the pressure drop also increased by 161% to 164%.