Numerical investigation of influence of rib orientation on discharge coefficients

Numerical simulation was conducted to investigate the flow field of internal cooling passages with both rib-roughened walls and film hole suction and discharge coefficients of film holes, with rib angles 45°, 60°, 90°, 120° respectively. A finite volume method with unstructured meshes was used to solve the three dimensional incompressible Navier-Stokes equations. The realizable k-ε turbulence model was used and standard wall function was used for near wall treatment. The coupling of velocity and pressure was performed using the SIMPLE algorithm. The numerical results show that the flow field of internal passages with both rib-roughened walls and film hole suction is a complex, secondary flow induced by ribs and changes the angles of the flow near the hole inlet and the hole axis, thus affects discharge coefficients. Discharge coefficients increase with the increase of rib angles. The calculated discharge coefficients are in good agreement with the experimental data.