The effect of modified trapezoidal vortex generators with different geometries on heat transfer

The effect of trapezoidal type vortex generators (VG) with modified geometry on heat transfer in a rectangular duct is numerically investigated. The numerical studies were carried out using the ANSYS Fluent 2020 R2 package program. Numerical studies were carried out under periodic boundary conditions for a channel with a test region length of 800 mm, a width of 200 mm and a height of 25 mm. The blockage ratio, which is the ratio of the VG height to the channel height, was kept constant at 0.48 and the angle of attack at 30°. The ratio of the distance between two VGs in the mainstream direction to the channel height, PR=LP/H, was set to 1.0, 1.5 and 2.0 for periodic distance ratio. For each PR, the effect of geometric modifications on heat transfer was investigated by taking the ratio of the VG minimum edge height to the maximum edge height, e/h=1.0 and 0.83, and the ratio of the VG inclined edge projection length to the VG base length, b/c= 0.25, 0.50 and 0.75, within the range of the Re=4121-25365. The GEKO turbulence model is used as the turbulence model, which is based on the k-ω formulation and provides flexibility for the user to adjust the model for various flow scenarios. In the numerical solutions, pressure-based-coupled-algotihm and pseudo-transient time step are used for the pressure-velocity coupling and the solutions are based on the finite-volume method. The fact that the TEF value of VGs is greater than 1 in the range of Re=4121-25365 for all PR, e/h, b/c ratios shows that the VGs investigated in this study offer an advantage over the smooth duct in terms of the enhancement of heat transfer. The highest TEF value was achieved to be 2.106 at PR=1.5, e/h=0.83 and b/c=0.75