THEORETICAL,NUMERICAL AND EXPERIMENTAL STUDY OF WATER HAMMER IN PIPE SYSTEM WITH COLUMN SURGE CHAMBER

A new kind of governing equations for water hammer based on the elastic column theory was proposed and adopted to analyse water hammer phenomenon in the pipe sys-tem with a vertical column surge chamber and water level fluc-tuation in the surge chamber during pressure transient. The wrongness existing in the classical governing equations for wa-ter hammer was analysed. A typical reservoir-valve pipe sys-tem was chosen as an example to verify the new governing e-quations numerically and experimentally. The finite difference method based on the method of characteristics was used to solve numerically the nonlinear characteristic equations. The temporal evolutions of transient volume flux and head and of water level fluctuation for various surge chamber configura-tions were worked out, assuming that the air in the surge chamber are compressible. The relevant experiment was con-ducted to verify the new governing equations and numerical method. The numerical and experimental results show that the new governing equations are valid and the conventional as-sumption that the pressure head at the base of a surge cham-ber equals that of the static head above it during pressure tran-sient is not always valid. The surge chamber generally reises the period of transient pressure wave in pipe system, reduces the maximum pressure envelope and lifts the minimum enve-lope substantially. The water level fluctuation in the surge chamber was numerically and experimentally observed. In-creasing the size of the surge chamber and/or decreasing the initial air pressure in the surge chamber enhance the effective-ness of the surge chamber in suppressing pressure wave.