الفهرس 
ABSTRACT
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Abstract
Hydraulic transients in water supply systems can produce significant variations of pressure fluctuations and flow velocity in the network pipelines. These could cause damaging extra stress and strain on pipes, joints, and fixtures. So, it is very important to simulate water hammer occurrence to determine whether dangerous pressures developed or not.
The present study is performed to investigate the effect of both sudden shut down of pumps and abnormal operation conditions on the transient pressure heads and flow rates with different protection cases for Assiut city water supply network. Water Hammer and Mass Oscillation (WHAMO) software was used in the simulation, which uses the implicit finite difference scheme for solving the momentum and continuity equations under unsteady-state conditions. Verification of the current results with those of WATERCAD and EPANET programs are also carried out. These comparisons revealed to an excellent agreement. Firstly, effect of using various protection devices such as non-return valve (NRV), open surge tank, air chamber and pressure relief valve (PRV) on the water hammer phenomenon, are simulated. The results indicated that using the open surge tank or air chamber with NRV protects the pipe network effectively from the harm of water hammer. Also, using PRV with non-return valve saves the pipe network from extreme pressures. Although using NRV only doesn’t have a great effect on the maximum pressure head than the normal case, it conserves the network from lower pressures than without protection one. Using non-return valve only or with pressure relief valve has the same flow fluctuations, which decrease more than the unprotected case. All protection methods safeguard the pipe network from the extremes of water hammer.