The Study of Heat Transfer Enhancement by Influence of Flow around Vortex Generators on the Turbulent Coherent Structure

摘要

This paper investigated heat transfer enhancement mechanism by the influence of vortex generators on the coherent structure of turbulent boundary layer. The flow and heat transfer characteristics of rectangle channel with bevel -cut half -elliptical column vortex generators are obtained using large eddy simulation(LES) and by the application of the hydromechanics software fluent. The instantaneous properties of velocity,temperature and pressure in channel are gaind .The coherent structure of turbulent boundary layer flow is showed and the characteristic of vortex induced by inclined -cut semi - ellipse vortex generator and its influence on turbulent coherent structure are analyzed. And the effect mechanism of turbulent coherent structure on flow field and temperature field are discussed. Based on the results, the control of the coherent structure induced by vortex generator plays more important role in heat transfer enhancement. Meantime, the coherent effects of increased wall heat transfer and decreased skin friction do not satisfy the Reynolds analogy. Furthermore, turbulence coherent structure directly affects the temperature gradient at the wall and the heat transfer enhancement mechanism of vortex generator is explained. Then we can seek suitable form of vortex generator and structure parameters, in order to achieve enhanced heat transfer and flow of drag reduction.