Heat transfer enhancement and flow characteristics of vortex generating jet on flat plate with turbulent boundary layer

Abstract

This paper presents the results of flow and heat transfer characteristics of vortex generating jet on a flat plate. A circular jet from the pipe nozzle is injected perpendicularly to the mainstream flow on flat plate Longitudinal vortex flow is induced for enhancing heat transfer on a constant heat flux surface. The effect of jet-mainstream flux ratio (J) on heat transfer was investigated by fix the mainstream flow at 10/s and varied the jet velocity corresponding to three jet-mainstream momentum flux ratios, J, of 0.06, 2.25, and 12.25. Temperature distribution on heat transfer surface with constant heat flux is captured by an infrared camera. The flow field is also investigated with numerical simulation. The results reveal that all heat transfer rates on the surface are higher than under the No-jet conditions due to generated counter-rotating vortex pair. Simulation results indicate that the low momentum flux vortex of J = 0.06 moves close to the surface and directly affects heat transfer enhancement, with a maximum increase of 40%. With a greater jet velocity the vortex pair moves away from the surface, the mainstream flows around the more stronger jet, and counter-flow secondary vortex is formed downstream of jet exit. Thus for J = 2.25, the disturbed mainstream exerts more influence on the surface heat transfer, up to a maximum of 50%. For J = 12.25, a maximum heat transfer, at 68% better than the No-jet scenario, is clearly achieved through the secondary vortex over a longer and larger area.