In order to reduce the flow resistance of shell sides of double-pipe heat exchangers enhanced by the winglet-type vortex generators and helical fins

a new kind of vortex generators

named streamlined vortex generator was proposed. Heat transfer characteristics and pressure drop behavior of the shell sides enhanced by the streamlined vortex generators and helical fins were investigated by experimental and numerical method. The comparisons on the performance between the streamlined vortex generators and the delta-winglet-pair(DWP)vortex generators were made. The enhancement effects of two installation modes for the streamlined vortex generators

common-flow-down (CFD) and common-flow-up (CFU) of streamlined vortex generators were observed. The drag reduction mechanisms of streamlined vortex generators were analyzed. The results showed that

compared with the delta winglet pair vortex generators

the same(Re < 8000)or slightly lower (Re > 8000)heat transfer coefficients can be achieved by using streamlined vortex generators. However

the drags can be reduced by 21% when the heat transfer areas and the angle of attacks were the same. Under the identical pressure drop condition

the comprehensive performance of the common-flow-up mode was a little better than that of the common-flow-down mode. The drag reduction mechanisms of streamlined vortex generators lay in the improvement of the velocity field and the pressure field.