Analysis and Stability of Closed Surge Tanks

The equations representing the water surface oscillations in a closed surge tank form a set of nonlinear ordinary differential equations when the system is considered as lumped. Because of the nonlinear terms present in the equations, a closed-form solution of the equations is not available. Several numerical methods ranging from single step methods to higher-order multi-step methods were used to find numerical solutions to the governing equations. As all the methods required a similar amount of CPU time, the degree of accuracy required would determine which numerical method should be used. The effect of various system parameters on the stability of the oscillations within a closed surge tank were examined. As the pressure and the volume of the enclosed air within a closed surge tank are the two parameters that mathematically and physically distinguish a closed surge tank from an open tank, their effect on presently-available stability criterion was closely examined and found to be most important