Numerical Analysis of Pulsating Water Jet Method for Mitigating the Vortex Rope

Hydraulic machines, that operate at part load can suffer severe pressure fluctuations. These fluctuations vary in frequency and amplitude depending on the operating point. The cause of these changes in fluctuations, such as a 70% flow rate regime, is the appearance of the rotating vortex (vortex rope). Removing the rotating vortex is a problem that has remained open over time. The fundamental problem, to which this work is addressed, is the study at several operating regimes of a new control method of vortex rope. The new method consists in the injection of a pulse water jet through the axis of the conical diffuser of the hydraulic turbines. The paper focuses to evaluate the new method with the help of 3D numerical simulation of the flow for different speeds of the vortex generator with and without pulsating jet. Thus, distribution of the meridian and circumferential velocity profiles were obtained for two sections, which clearly shows the mitigation of the vortex rope when introducing the pulsating jet.