Numerical simulation and design of non-uniform arrangement of circular and elliptical holes on the effectiveness of film cooling of a gas turbine blades

The objective of this paper is to designed a nonuniform arrangement of elliptical holes for film cooling (FICO) on gas turbine blades. The optimal distance between rows of holes (1–3) was determined to maximize FICO effectiveness. The three-dimensional geometry of the problem (Circle, horizontal elliptic, and vertical elliptic) was modeled based on an existing experimental sample. The turbulent steady-state incompressible single-phase flow was modeled using conservation equations and considering the blowing ratio (0.25–2), adiabatic FICO efficiency, von Mises stress (VMS), and hydraulic radius relationships. Results showed that elliptical holes with a major diameter normal to the flow had the highest centerline and laterally averaged effectiveness values. Additionally, holes that were more laterally stretched out had higher efficiency. The best effectiveness was achieved at an optimal blowing ratio of 0.75. Furthermore, the maximum von Mises stress was higher in cases with smaller distances between rows. Von Mises stress analysis revealed that elliptical openings with a large diameter perpendicular to the flow caused the lowest thermal stress in the solid body. When cooling with three rows of elliptical holes, a larger distance between the second and third rows resulted in higher effectiveness and lower maximum VMS at an optimal distance.