Introduction of Combined Usage of Overset Grid Method in Conjugate Heat Transfer Simulation

The conjugate heat transfer simulation is expected to simulate precise temperature distributions of turbine cooling structures and contribute to the reduction of cooling air usage. However, the generation of computational grids for highly complicated cooling structures in turbine blade is a quite difficult work, especially in the conjugate simulation because grids for fluid and solid regions should be generated simultaneously. In this study the combined usage of the overset grid method with the attached multiblock grid method is introduced for the grid generation with less effort. In the original UPACS flow solver, the overset is treated as one type of boundary conditions where the data are interpolated from the background grid blocks. If the interpolations of data are allowed along the solid surface which is the connecting boundary of fluid and solid grid blocks, the heat flux calculation becomes quite complicated and the benefits of longstanding researches on the turbulence models for boundary fitted grids cannot be used, thus the overset treatments have been limited among the same type of calculation blocks, that is, the fluid blocks should be on the background grid of fluid region and the solid blocks should be on the background grid of solid region. The procedure to create grids with the above restriction has also developed. Numerical result using the overset grid method is compared with the conventional multi-block grid result for evaluation. With this method, the grid generation labor for such as parametric simulations of different arrangements of film holes in a turbine blade will be greatly reduced.