Numerical study of flow and heat transfer in the channel of panel-type radiator with semi-detached inclined trapezoidal wing vortex generators

To improve heat dissipation performance of panel-type radiator for transformer, this study investigated the flow and heat transfer characteristics of semi-detached inclined trapezoidal wing vortex generator (SDITW) in a closed channel on the air-side of the radiator. The SDITW was compared with the inclined delta wing (IDW) and inclined trapezoidal wing (ITW) channels. The effects of SDITW relative separation height (e(1)/e(2)), longitudinal pitch (p l), blockage ratio (e/(0.5H)), and inclination angle (alpha) were analyzed. First, compared with the IDW and ITW channels, the SDITW channel generates stable corner vortices and produces weaker transverse vortices and lower flow resistance due to the semi-detached structure of the wing. For Re = 5,125-15,375, the overall heat transfer performance (performance evaluation criteria; PEC) of the SDITW channel increases by 0.5-8.9 and 1.7-4.9% as compared with IDW and ITW channels, respectively. Furthermore, for the same e/(0.5H) and alpha, both the Nusselt number ratio and friction factor ratio of SDITW channel increase as e 1/e2 and p l decrease. For p l = 70 mm, the SDITW channel exhibits a relatively better overall heat transfer performance. For the same e(1)/e(2) and p l, the PEC of SDITW channel is maximum and the overall heat transfer performance is best when e/(0.5H) = 0.3 at Re = 10,250 and alpha = 30(degrees)-60(degrees).