Numerical Study of Flow and Heat Transfer in the Air-Side Channel of Panel-Type Radiator with Novel Vortex Generators

A novel hollow triangular conical-wing vortex generator (HTCVG) was proposed to enhance the heat transfer performance of a panel-type radiator for oil-immersed transformers. A numerical investigation was conducted to compare the HTCVG with a common delta-wing vortex generator (DWVG) and a trapezoidal-wing vortex generator (TWVG). The numerical model was validated against empirical correlations and experimental data, with average deviations of Nu and f within 4.67% and 8.74%, respectively. The results showed that the HTCVG generates vortices that disrupt the thermal boundary layer more persistently and uniformly and promote fluid mixing. In the range of Re = 5146–15,439, the HTCVG achieves a higher performance evaluation criterion (PEC) than the TWVG and DWVG, with improvements of 10.98–12.61% and 5.61–7.59%, respectively. Based on the averaged PEC values under different Re conditions, a selected high-performing parameter combination was obtained at β = 60°, α = 35°, h1 = 8 mm, d = 13 mm, and p1 = 70 mm. Under this combination, the HTCVG achieves the highest PEC among the vortex generators reported in the literature when Re > 15,000, indicating the best overall heat-transfer performance and demonstrating its engineering potential for improving the cooling capacity of transformer panel-type radiators.