Practical Conjugate CFD Heat Transfer Design Methods for Complex Turbine Components

Modern cooled gas turbine components are typically characterized by small-scale features (turbulators, impingement holes, and film cooling holes) and complex physics (boundary layer transition, separated shear layers from turbulators, and unsteady mixing of film coolant into the mainstream). The geometric complexity and computational rigor required to resolve the physics yields conjugate CFD/heat transfer analysis durations that are not practical for a target component design iteration cycle of ~4 weeks. Consequently, current technology limits use of conjugate CFD to sub-models models of reduced physical rigor (RANS), or simplified cooling schemes (i.e.: no film holes). Component designers require accurate prediction of the stress/temperature field over the entire component; accordingly, industry needs a method of physically rigorous modeling (DES/LES) in critical regions. For non-critical regions, the proposed conjugate CFD/thermal design methodology omits the small scale features (impingement holes, film holes, or turbulators) from the mesh, and instead meshes only the large-scale flowpath and internal cooling passages. Grid extraneous source terms (mass/momentum/energy) are used to capture the effect of small-scale features in non-critical regions to keep the analysis time practical. The novel aspect of this approach is the manner in which source terms are created, controlled, and integrated into the converging full-scale conjugate solution.