Calculation of Turbulent Flows in a Hydraulic Turbine Draft Tube

Abstract

A numerical method to simulate three-dimensional incompressible turbulent flows has been developed and applied to the calculation of various flow situations in a draft tube. The conservative form of the primitive-variable formulation of the Reynolds averaged Navier-Stokes equations, written for a general curvilinear co-ordinate system, is employed. An overlapping grid combined with opposed differencing for mass and pressure gradients is used. All the properties are stored at the center of the same computational cell which is used for mass and transport balances. The k–ε model is used to describe the turbulent flow. The boundary conditions for the turbulent properties are treated with a particular attention.