Influence Of Geometric Parameters On The Flow And Heat Transfer Characteristics In Rectangular Cross Section With Triangular Vortex Generators

The plate-fin heat exchangers are widely used in various fields,which is considered to be one of the most promising heat exchangers.At present,the research of plate-fin heat exchangers is mainly focused on its fins.Most of them adopt the method of increasing the heat transfer area or destroying the thermal resistance boundary layer on the surface of the fin to achieve the purpose of strengthening heat transfer.The triangular vortex generator installed on the three sides of the rectangular channel in this thesis can not only increase the heat transfer area of the heat exchange channel,but also can form the longitudinal vortex to improve the heat transfer performance of the heat exchanger.One channel of the fins is selected as the study domain in the paper.Firstly,the region composed of the five minimum periodic unit is taken as the calculation region and it is meshed.Secondly,the body fitted coordinate is used.Thus,coordinates are transformed into the computational domain.The governing equations are transformed and discretized in dimensionless form.In order to study the influence of the geometric parameters of the vortex generator on the flow and heat transfer characteristics of the channel,the aspect ratio rat of the rectangular channel,the high H of the triangular vortex generator,the height H of the device,the attack angle?of the vortex generator,and the relative distance S between the vortex generator are changed at the condition of Re=300~1100.Finally,the influence of geometric parameters on Nusselt number,friction factor,and the secondary flow intensity of the channel are analyzed,and the resulting numerical results are fitted to obtain the criterion correlation.The main results can be summarized as:with in the scope of the study,under the same structure,with the increase of Reynolds number Re,Nusselt number(Nu)increases and the friction coefficient f decreases.Rat of rectangular channel have certain influence on the flow and heat transfer in the channel.At large Re,when the aspect ratio is 0.5?rat?1.4,Nu increases first and then decreases with the increase of the aspect ratio of rat.f also increases first and then decreases,reaching the maximum when the ratio of high to wide rats is 0.8.When the aspect ratio 1.7?rat?2.0,Nu and f gradually increase with the increase of the aspect ratio rat,and both Nu and f are larger than rat=0.8.When the geometric parameters?and H increase,Nu and f increase.For the relative spacing S of the triangular vortex generators,Nu and f decrease as S increases.Under the small Re,the geometric parameters has little effect on Nu.Under the same structure parameters the secondary flow intensity Se_m and Nu have the same tendency as the Reynolds number Re increases.