Modal Analysis on a Runner Chamber for a Large Hydraulic Bulb Tubular Turbine

The vibration was severe for a runner chamber of a large hydraulic bulb tubular turbine, which caused some cracks. The PRO/E software was adopted to establish a 3D model of the runner chamber. Based on ANSYS Workbench V14.5, a modal analysis was done. Its natural frequencies and modal shapes were obtained. The influence on modal characteristics with the runner chamber's structure was discussed. The study shows that the reinforce stiffener's thickness, the circumferential endlessband and their thicknesses have few effect on the modal characteristics of the runner chamber, the latticed reinforce stiffener has more effect on the modal characteristics. These results will provide the basis for product optimum design, so that its natural frequencies stagger these frequencies of field vibration, the resonance and the crack do not occur in the runner chamber.