الفهرس 
Importance of the Point of Research
Research Works for Water Hammer and Protecting Devices.Only 14 pages are availabe for public view
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Abstract
Water hammer is a hydraulic phenomenon that causes severe changes in the hydraulic operating flow pressures. This phenomenon is caused due to an unexpected event in the flow such as sudden closing/opening of a valve or power failure of a pump installed along the pipeline system.
The pressure increase, due to water hammer, depends on the initial speed of the flow, length of the pipelines and the sound speed of the pressure waves. Controlling the water hammer pressure becomes indispensable, so a transient surge analysis is required to investigate the points of severe changes along with the pipeline system, and then the proper transient control device can be selected. Among the transient control devices, there is the compressed air vessel (CAV) which is a pressure control device that is used to control the positive and negative pressure changes. There are two factors that affect the sizing of the air vessel namely the initial trapped air volume (VFR) and the throttling aperture size of the air vessel. An experimental test rig composed of a long water pipe provided with a rapid closing valve and the essential pressure instruments is designed and used to create a water hammer pressure wave. The rig is also equipped with a compressed air vessel to test
its effect on depressing the pressure wave. A simulated computer program based on the solution of the one-dimensional unsteady flow equations is also written to model the water hammer phenomena and the performance of the compressed air vessel, both the experimental and the model results are compared and discussed.
Both the experimental and model results show the high capability of the air vessel to dampen water hammer pressure. The water hammer head could be reduced from 300m to 15-50m depending on the used orifice diameter and the initial air volume inside the air vessel.
The orifice diameter shows a high effect on the performance of the air vessel and that the air vessel should be throttled to control the upper and lower limit of water hammer pressure head.
The initial volume of the trapped air should be in the range of 53% to 78% of the total volume of the air vessel, so that the air vessel works effectively.