Longitudinal vortices can enhance heat transfer with small pressure loss penalty and has been widely applied in heat transfer enhancement of tube bank fin heat exchangers. Setting winglet vortex generator (VG) that can generate longitudinal vortices on the fin surface is a promising technique to enhance the airside heat transfer. In order to obtain better heat transfer performance

lots of VGs are punched out of the fin surface

so several longitudinal vortices appear in the flow channel. The interaction of vortices affects the intensity of longitudinal vortices and their effect on heat transfer enhancement. In this paper

the interaction of counter rotating longitudinal vortices generated by winglet VGs is quantitatively analyzed under different transversal distances between VGs. The effects of interaction of vortices on the intensity of vortices

flow field structure and heat transfer are discussed in detail by using the longitudinal vortex intensity parameter Se. The results show that the interaction of counter rotating longitudinal vortices increases with the decrease of transversal distance between VGs. When the distance between VGs is zero

the interaction between counter rotating vortices is the most serious

while the values of ΔSe

ΔNu and Δf get the minimum values. The maximum decreasing percentage of ΔSe

ΔNu and Δf are 45%

50% and 38%

respectively. The interaction between counter rotating vortices does not necessarily decrease the heat transfer of longitudinal vortices. The heat transfer performance depends on not only the intensity of vortices but also their structure. The common flow region formed between counter rotating longitudinal vortices is beneficial for heat transfer enhancement. Due to the interactions of counter rotating longitudinal vortices and their effect on heat transfer enhancement

an optimum arrangement of VGs exists for better heat transfer performance. The best heat transfer performance can be obtained when the transversal distance between the VGs is twice the projected length of the base of VGs.