Thermal-hydraulic performance investigation of the cooling passage featuring the ridged V-shaped dimple

The ridged V-shaped dimple (RVD) is proposed to improve the thermal-hydraulic performance of the dimpled cooling passage by generating a ridge at the junction of the spherical dimple and V-shaped dimple. The impacts of arrangements (staggered, inline), geometric parameters (the length l/D of RVD leg, the angle α between two legs, the spacing s/D between the spherical dimple and V-shaped dimple in RVD, the depth-to-diameter ratio of dimple), and Reynolds number (Re = 8,500-50,000) on the thermal-hydraulic performance of RVD are investigated through numerical simulations. Results demonstrate that RVD significantly improves thermal-hydraulic performance by forming larger and stronger longitudinal vortexes and disrupting the boundary layer. The inline RVD has a higher thermal-hydraulic performance compared to the staggered RVD due to the stronger disturbance. Moreover, the RVD is appropriate for enhancing the thermal-hydraulic performance of deeper dimples, case 0.3-0.1 has the largest PEC (1.38-1.50) compared to other dimpled cases, and it achieves a 10.50%-18.18% increase over the corresponding typical VD. Finally, the correlations for Nu/Nu0 and f/f0 of inline RVD are proposed based on the numerical results, and the deviations between the predicted results and the simulated results are 10% for Nu/Nu0 and f/f0.