Numerical simulation of threedimensional transient turbulent flow in the whole flow passage of a Francis turbine based upon the Reynolds averaged N-S equations was conducted with the large eddy simulation (LES) technique on Smargorinsky model and sliding mesh technology. The steady flow data simulated with the standard k-ε model were used as the initial conditions for the unsteady simulation. The large scale structures evolving in spatially and temporally were visualized by the software Fluent 6.3, using unstructured hybridgrid and PISO algorithm. The evolution details of the large scale structures such as eddy from generate to shedding in vane cascades and blade passages were well captured at special case. The results show that LES can well simulate transient turbulent flow in a Francis turbine with complex geometry. The computational method provides some reference for exploring mechanism of eddy formation in a complex turbulent of hydraulic machinery.
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