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ABSTRACT
The flow and heat transfer characteristics of various rib configurations on a concave channel surface with effusion holes were investigated. A semicylindrical channel with three rows of effusion holes was used to simplify the blade leading edge and eight kinds of ribs were attached on the internal concave surface for comparison. Continuous and broken ribs were both applied at 90°, as were upstream-pointed V-shaped and downstream-pointed V-shaped ribs. The Reynolds-averaged Navier–Stokes equation was solved using commercial software. The result included the divided-area-averaged and local Nusselt number distribution; the overall average Nusselt number on the concave surface is also discussed.
Nomenclature
| Cp | = | heat capacity (J/K) |
| d | = | diameter of effusion hole (mm) |
| dsi | = | area of each element (m2) |
| D | = | diameter of concave channel (mm) |
| Dh | = | hydraulic diameter of concave channel (mm) |
| h | = | heat transfer coefficient (W/m2·K) |
| kair | = | ideal gas thermal conductivity (W/(m·K) |
| l | = | V-shaped rib helix height (mm) |
| L | = | concave channel length (mm) |
| = | mass flow rate of nozzle inlet (kg/s) | |
| Nu | = | Nusselt number |
| Nu0 | = | reference Nusselt number |
| Nui | = | Nusselt number on simulation element |
| = | average Nusselt | |
| p | = | rib-to-rib pitch (mm) |
| Pr | = | Prandtl number |
| Re | = | Reynolds number |
| si | = | each simulation element area (mm) |
| T | = | temperature (K) |
| u | = | velocity (m/s) |
| w | = | rib thickness (mm) |
| x | = | streamwise direction of channel (mm) |
| β | = | V-shaped rib helix angle (°) |
| θ | = | angle between each row of effusion holes (°) |
| μ | = | viscosity (N…/m2) |
| μ | = | viscous dissipation heat source (J) |
| ρ | = | density (kg/m3) |
| τij | = | symmetric stress tensor (m/s2) |
Nomenclature
| Cp | = | heat capacity (J/K) |
| d | = | diameter of effusion hole (mm) |
| dsi | = | area of each element (m2) |
| D | = | diameter of concave channel (mm) |
| Dh | = | hydraulic diameter of concave channel (mm) |
| h | = | heat transfer coefficient (W/m2·K) |
| kair | = | ideal gas thermal conductivity (W/(m·K) |
| l | = | V-shaped rib helix height (mm) |
| L | = | concave channel length (mm) |
| = | mass flow rate of nozzle inlet (kg/s) | |
| Nu | = | Nusselt number |
| Nu0 | = | reference Nusselt number |
| Nui | = | Nusselt number on simulation element |
| = | average Nusselt | |
| p | = | rib-to-rib pitch (mm) |
| Pr | = | Prandtl number |
| Re | = | Reynolds number |
| si | = | each simulation element area (mm) |
| T | = | temperature (K) |
| u | = | velocity (m/s) |
| w | = | rib thickness (mm) |
| x | = | streamwise direction of channel (mm) |
| β | = | V-shaped rib helix angle (°) |
| θ | = | angle between each row of effusion holes (°) |
| μ | = | viscosity (N…/m2) |
| μ | = | viscous dissipation heat source (J) |
| ρ | = | density (kg/m3) |
| τij | = | symmetric stress tensor (m/s2) |
