Large eddy simulation of vortex shedding in an axial flow turbine.

摘要

Vortex shedding of a two-dimensional axial turbine stator vane with varying rotor speeds has been simulated using Computational Fluid Dynamics (CFD) with Large Eddy Simulation (LES) and the Smagorinsky-Lily (S-L) subgrid scale (SGS) model. Simulations were performed with Fluent, a commercial CFD code. The results of the frequency of vortex shedding was found to vary with rotor speed, but the Strouhal numbers remained nearly constant, ranging from 0.18 to 0.22. For this study Kolmogrov Scale based Modeling (KSM) was developed based on the microscales of turbulence. The KSM method was applied to determine the grid size and time step for LES where SGS turbulence is expected to be homogenous and isotropic. To support the primary study of flow past turbine stator vanes, the CFD solver with the LES model was applied to flow pas a flat plate, a cylinder, and the Goldman stator. LES was not successful in accurately modeling the flat plate, but for the case of flow past a cylinder at a supercritical Reynolds number, the resulting Strouhal number was within 5.4% of experimental data. Subsonic compressible flow was also validated with flow past the Goldman stator, and results of surface pressure from the LES model matched closely with experimental values.