A Design Criterion for Dynamic Stability of Eccentric Tainter-Gates

Abstract

Tainter gates used for regulating the back water level of dam may be designed so that the skinplate center is kept under the trunnion pin. Such gates may be called an “eccentric Tainter-gate”, which is statically stably but dynamically unstable. This study presents a design criterion for dynamic stability of eccentric Tainter gates, which is theoretically derived in a practical form, that is, in a non-dimensional expression of the Scruton number representing the mass-damping parameter vs. the Froude number representing the dynamic similarity of fluctuating flow in the back water. In addition, in-air and in-water free vibration tests are made for two of Tainter-gate models with different size and eccentricity, and the measured data of Scruton number is plotted over the tested Froude number, and the design criterion for dynamic stability of the eccentric Tainter gates is verified for its practical validity.