Heat transfer enhancement and flow characteristics of internal cooling channels with slit vortex generators

Vortex generators can boost heat transfer performance greatly, although they are always linked with significant pressure drops. In this article, to reduce the pressure drop while improving the thermal efficiency simultaneously, traditional delta winglet pair vortex generators (DWPVG) with slits are installed in the rectangular channel. Besides, the effects of slits on DWPVG on pressure drops and heat transfer performances for different Reynolds numbers are studied. To reveal the fluid flow characteristics, three-dimensional calculations using a confirmed turbulence model are undertaken and the underlying thermo-fluid processes are exposed for the various investigated cases. To reveal the overall thermal performance of different cases, two overall thermal performance factors Nu(ave)/Nu(0)/(f/f(0)) and Nu(ave)/Nu(0)/(f/f(0))(1/3) are used. The findings suggest that when the fluid flows through slits, induced vortices are located closer to the bottom surface, generating an improvement of the local Nusselt number behind DWPVG. Furthermore, DWPVG with slits can decrease the pressure drop, but also make the local thermal efficiency improve in the channel with a high blocking ratio. Moreover, the increase in the overall thermal performance of the slit DWPVG channel with a high blocking ratio is enlarged with the Reynolds number raise. Besides, the highest heat transfer enhancement is provided by opening slits on five DWPVGs in the rectangular channel.

Automated summary

This article investigates the effects of traditional delta winglet pair vortex generators (DWPVG) with slits on pressure drops and heat transfer performances in a rectangular channel. Through three-dimensional calculations and analysis of thermo-fluid processes, it is found that induced vortices are located closer to the bottom surface, improving the local Nusselt number behind DWPVG when the fluid flows through slits. Furthermore, DWPVG with slits decreases the pressure drop and improves the local thermal efficiency in the channel with a high blocking ratio. The overall thermal performance of the slit DWPVG channel with a high blocking ratio increases with the increase in Reynolds number, and the highest heat transfer enhancement is achieved by opening slits on five DWPVGs in the rectangular channel.