Numerical medoleing of the water hammer phenomena with FLUENT software

Water-hammer phenomenon occurs in pressure pipes due to sudden change in boundary conditions such as a quick opening and closing of the valves, sudden connection and disconnection of a pump or turbine and similar situations. In this case, as a result of sudden changes in the momentum of the flow, high speed pressure wave flows through the pipelines and if the maximum pressure created goes beyond the maximum pressure allowed for the system, its destruction is inevitable. Therefore it is essential to consider these factors during designing of hydraulic systems.In this study the water hammer phenomenon is simulated with the help of FLUENT software and implementation of UDF s(user defined functions) in the program to consider different aspects such as wall and fluid elasticity. The results of this modeling process were verified by Araya Experiment for water-hammer and after the verifications, the data obtained from the model were used to analyze the water-hammer phenomenon in series of pipes and their effect on the severity of the water-hammer impact. It has been derived for series of pipes, combination of reflected pressure with initial pressure in pipe junction creates waves with higher pressure head and lower frequency. These effects are intensified especially when origin of water hammer is in pipe with larger section. FLUENT can be used as a tool for initial estimation of water hammer phenomenon in series of pipes, and obtaining value of primary head in pipe systems.