Modeling of film cooling - Part II: Model for use in three-dimensional computational fluid dynamics

Computational fluid dynamics (CFD) has recently been used for the simulation of the aerothermodynamics of film cooling. The direct calculation of a single cooling hole requires substantial computational resources. A parametric study for the optimization of the cooling system in real engines, is much too time consuming due to the large number of grid nodes required to cover all injection holes and plenum chambers. For these reasons, a hybrid approach is proposed, based on the modeling of the near film-cooling hole flow, tuned using experimental data, while computing directly the flow field in the blade-to-blade passage. A new injection film-cooling model is established, which can be embedded in a CFD code, to lower the central processing unit (CPU) cost and to reduce the simulation turnover time. The goal is to be able to stimulate film-cooled turbine blades without having to explicitly mesh inside the holes and the plenum chamber The stability, low CPU overhead level (1%) and accuracy of the proposed CFD-embedded film-cooling model are demonstrated in the ETHZ steady film-cooled flat-plate experiment presented in Part I (Bernsdorf Rose, and Abhari, 2006, ASME J. Turbomach., 128, pp. 141-149) of this two-part paper. The prediction of film-cooling effectiveness using the CFD-embedded model is evaluated.