Heat Transfer Characteristics And Flow Behaviors Of The Longitudinal Vortex Generators In The Channel Flow

In this paper, theoretical analysis, numerical simulation and experiments have been performed to investigate the heat transfer effects and flow characteristics of longitudinal vortices in the channel flow.In the part of theoretical analysis, some conceptions about vortex in the flowing field and how the vortex generated and developed have been interpreted, and then its heat transfer enhancement mechanism can be explained. What's more important is that a three-dimensional field coordination (synergy) equation is deduced on the basis of two-dimension field coordination equation between velocity and temperature field for the entire flow and heat transfer domain. It is found that the heat transfer enhancement degree not only depends on the velocity and flow properties of the fluid, but also on the coordination degree between velocity and temperature field. So it is believed that there is a large room for the heat transfer enhancement study under the guide of the field coordination principle.In the part of experiments, four kinds of vortex generator (VG) and pouring mould are designed and made in order to finish the experiments smoothly. Experiments have been performed, in which the heat-mass transfer analogy and the naphthalene sublimation technique are employed, in the tunnel system to investigate the heat transfer and flow characteristics of Delta Vortex Generator (DVG), Rectangular Vortex Generator (RVG), Delta Wing-let Vortex Generator (DWVG) and Rectangular Wing-let Vortex Generator (RWVG) respectively. In the range of 2.0×10~5~5.5×10~5 Reynolds number, the effect of different height width ratio and different impacted angles on the heat transfer enhancement are studied, and the mean and local heat transfer characters are obtained. The experimental results can be concluded as following: a) there is an optimized impacted angle, which is 60°, for the DWVG and RWVG; b) the local convective heat transfer coefficient with VG is about 70% higher than plane without VG, and the mean convective heat transfer coefficient is about 30% higher; c) the physical dimension is one of important factors, and with the increment of height of VG, the effect of heat transfer enhancement becomes better based on the paper's experimental results. In conclusion, DWVG is the best way. At last, the experimental results validated the field coordination principle perfectly.In the part of computer calculation, it is carried out by virtue of Computational Fluid Dynamics (CFD) software which is called FLUENT. Firstly, a three-dimension model wais build by using GABIT, and meshed into tiny grids. Then, the finite volume...