Simulation of unsteady flow and runner rotation during shut-down of an axial water turbine

The paper describes a novel method for prediction of water turbine characteristics during transient operating regimes. It is based on numerical flow simulation with finite volume method. The whole axial turbine flow-passage is considered in the computation. During the observed time interval, the runner grid rotates and both the distributor vanes and runner blades simultaneously change their positions. The rotational speed of the runner is dependent on computed flow field. Rotational speed, axial force and pressure at selected points are predicted and compared to prototype measurement data. Convergence of results has been shown by using better influential computational parameters. The method was applied on air industrial case to show that it is useful for engineering practice.