![Sample our Engineering & Technology journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5933/TOC-Subject-Sample-2021-Engineering-Tech.jpg"})
ABSTRACT
In this study, numerical simulations are performed to investigate the effect of dimple location on the flow structure and heat transfer characteristics in a 90°-turned channel with pin fins. Results of the flow structure, heat transfer on the endwall, and friction factor are included in this study. It is found that the dimple location has an impact on the flow structure and heat transfer both for the pin fins arranged with in-line and staggered layout. The horseshoe vortex near the pin fin is influenced by the location of the dimple. The dimple enhances the Nusselt number on the endwall surface significantly. In addition, the dimple location has an effect on the low-speed recirculation, impingement, and vortex which are generated by the dimple. However, the dimple has very limited effects on the friction factor for all cases. It is also found that the area goodness factor and volume goodness factor are improved by the dimple.
Nomenclature
| CFD | = | computational flow dynamics |
| TKE | = | turbulent kinetic energy |
| dd | = | dimple diameter (mm) |
| dp | = | pin fin diameter (mm) |
| Dh | = | hydraulic diameter of the inlet (mm) |
| f | = | friction factor |
| f0 | = | friction factor in smooth channel |
| h | = | heat transfer coefficient (W/m2 · K) |
| H1 | = | inlet height (mm) |
| H2 | = | outlet height (mm) |
| L1 | = | channel length (mm) |
| L2 | = | channel width length (mm) |
| L3 | = | outlet extent length (mm) |
| Nu | = | Nusselt number |
| Nu0 | = | Nusselt number in smooth channel |
| Pr | = | Prandtl number |
| Pin | = | inlet total pressure (Pa) |
| Pout | = | outlet total pressure (Pa) |
| q | = | wall heat flux (W/m2) |
| Re | = | Reynolds number |
| S1 | = | distance between the dimple and pin fin in the streamwise direction (mm) |
| S2 | = | distance between the dimple and pin fin in the spanwise direction (mm) |
| Sx | = | pin fin streamwise spacing (mm) |
| Sy | = | pin fin spanwise spacing (mm) |
| Tin | = | inlet air temperature (°C) |
| δ | = | dimple depth (mm) |
| λ | = | thermal conductivity of air (W/m · K) |
| μ | = | dynamic viscosity (Pa · s) |
| ρ | = | density of air (kg/m3) |
Nomenclature
| CFD | = | computational flow dynamics |
| TKE | = | turbulent kinetic energy |
| dd | = | dimple diameter (mm) |
| dp | = | pin fin diameter (mm) |
| Dh | = | hydraulic diameter of the inlet (mm) |
| f | = | friction factor |
| f0 | = | friction factor in smooth channel |
| h | = | heat transfer coefficient (W/m2 · K) |
| H1 | = | inlet height (mm) |
| H2 | = | outlet height (mm) |
| L1 | = | channel length (mm) |
| L2 | = | channel width length (mm) |
| L3 | = | outlet extent length (mm) |
| Nu | = | Nusselt number |
| Nu0 | = | Nusselt number in smooth channel |
| Pr | = | Prandtl number |
| Pin | = | inlet total pressure (Pa) |
| Pout | = | outlet total pressure (Pa) |
| q | = | wall heat flux (W/m2) |
| Re | = | Reynolds number |
| S1 | = | distance between the dimple and pin fin in the streamwise direction (mm) |
| S2 | = | distance between the dimple and pin fin in the spanwise direction (mm) |
| Sx | = | pin fin streamwise spacing (mm) |
| Sy | = | pin fin spanwise spacing (mm) |
| Tin | = | inlet air temperature (°C) |
| δ | = | dimple depth (mm) |
| λ | = | thermal conductivity of air (W/m · K) |
| μ | = | dynamic viscosity (Pa · s) |
| ρ | = | density of air (kg/m3) |