Abstract: Numerical simulation was conducted to investigate the flow field of internal cooling passages with both rib-roughened walls and film hole suctions 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 imcompressible 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 suctions was complex,secondary flow produced by ribs changed the angles of the flow near the hole inlet and the hole axis,thus affected discharge coefficients.Discharge coefficients increase with the increase of rib angles.The calculated discharge coefficients are in good agreement with the experimental data.