Vibration Characteristics of a Tubular Turbine Prototype at Different Heads with Considering Free Surface and Water Gravity

Tubular turbines are widely used in low water head and tidal power development due to their straight flow path, simple structure, wide efficient area. However, the severe vibration during actual operation greatly affects safe of tubular turbine. This study performs a numerical calculation turbine, which meets machine conditions considering free surface gravity; compares analyzes characteristics pressure fluctuation spectrum turbine under different heads; verifies comparison with test results explore mechanism Research show that large difference is observed between top bottom runner chamber, needs experience periodic fluctuations rotation combined effect hydrostatic hydrodynamic pressure. Under heads, obvious turbulence high turbulent kinetic energy areas draft tube influence shape blade wake vortex. The mainly concentrated influenced by gravity structure transverse cantilever beam. amplitude largest when frequency inside passing at each head, so maximum position located runner. research serve as guide for design horizontal