Design And Investigation On Heat Transfer Enhancement With Longitudinal Vortex Generators In A Rectangular Channel

As we all know, heat transfer enhancement technology has been developing quickly since theincoming of the21st century, which gives a new method of solving the problems of a shortage of energy,plays an important role in many industry areas. Many scholars focus on mechanism analysis of heattransfer enhancement in recent decades, which puts existing technology into the use of our life, promotesthe innovation and progress of heat transfer enhancement technology at the same time. Technology oflongitudinal vortex(LV) heat transfer enhancement, as a new-type of heat transfer enhancementtechnology, could reduce the thickness of boundary layer, increase turbulent kinetic energy and reduce theheat resistance.Based on mechanism of heat transfer enhancement of longitudinal vortex, this thesis came up with anew effective longitudinal vortex generator(LVG),and analysized the flow structure and heat transferperformance of it with the method of simulation. Compared with rectangular-shape rib, The new rib withhelical shape provided a better heat transfer performance within a slight increase of resistance loss.Thisthesis provided three kinds of arrangements of the helical ribs installed on both of the walls of therectangular channel, and ultimately determined that cross-staggered arrangement is the best type, namedas cross-helical ribs. To obtain the channel resistance loss and heat transfer coefficient, this paperestablished entrance section rectangular channel unit model to compute the pressure loss and nusseltnumber under a series of Reynolds number,and simulate influence the change of attact angleβ,and theninstalls10pairs of cross-helical ribs inside of a long rectangular channel to get the influence of Reynoldsand Prandtl number.To determine the effects of geometry parameters including the height a,width b,lengthc and lead angle α,this paper established models of a=1-5mm, b=5/3-25/3mm, c=20-40mm, α=90°-450°ina plate channel.To get the influence of the way of arrangement within the channel, this paper establishedmodels of n=2-10and simulated these heat transfer processes in the same condition and dicussed theresults of pressure loss and nusselt number.We got conclusion from above works that the cross-helical ribs designed in this thesis had a betterheat transfer performance compared with some traditional LVGs, and the rules of flow structure and heattransfer performance with variation of conditions and parameters made a foundation of futureexperiments.