Deriving the Governing Equations for Shock Damper to Model andControl the Unsteady Flow Caused by Sudden Closer of Valve

摘要

This paper focuses on deriving the governing equations for an instrument used in water flow systems known as “shock damper”. Shock damper is a tremulous tool with a single degree of freedom system which includes tank, connecting pipe, mass, spring, and a damper. This tool is then applied as a boundary condition for characteristic lines equations. Additional equations will be included by considering conservation of mass, momentum, and energy. This system of equations is then explicitly solved at each time step. In order to illustrate the performance of the shock damper, a gravity-feed system is considered with and without a damper. The control valve of this system will suddenly be shut to impose a water hammer condition. Then, unsteady flow parameters such as minimum/ maximum of flow velocity and pressure are evaluated along with a sensitivity analysis. Results demonstrate that shock damper despite being simple and economically efficient, is highly capable of moderating unsteady flow characteristics.