الفهرس 
Water Hammer DescriptionOnly 14 pages are availabe for public view
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Abstract
In a closed irrigation pipeline installation, if the flow of water is suddenly brought to rest by pump trips or any othe obstructions, the momentum of moving water is converted into positive and negative pressures which will generate surge waves. The waves will be transmitted along the pipeline with the speed of sound about 1300 m/s, (water at 20 oC). This is defined as the water hammer phenomenon or the hydraulic transient. The high pressure may cause rupture of pipe and the low pressure can lead to cavitation and water column separation. It is important to investigate and analyze the irrigation pipe installation to define the transient effects and try optimum solution to control or prevent water hammer events. The aim of the study is to analyze analytically,practically and numerically investigations to find out a solution for this phenomenon. Firstly, analytical investigation has been done on polyvinylchloride pipeline 2000 m long of pressure class 4 bar (PN4), with diameters 450, 500, 560, 630,710 and 800 mm and flow rates 1200, 1350, 1500, 1650 and 1800 m3/h with elevation differences of 40 m. The analysis has been done for the same pipeline data with pressure class 6 and 10 bar. The steady state pressures were obtained and Joukowsky equation was used to calculate the maximum and the minimum pressure, the results were compared with the permissible pressure classes for the pipeline 4, 6 and 10 bar,then the values of over pressure and negative pressure along the pipeline has been represented to choose the required protection devices. Secondly the thesis provided a complete design for PVC pipeline PN6, the pipeline length is 2000 m,elevation difference of 40 m and discharge 1200 m3/h.Analytical and Applied Flow Technology impulse analysis provided to determine the values of transient pressure during power failure. Design criteria for system equipment and control devices such as (air vessel, surge tank...), at an adequate economic analysis had been done to estimate the diameter that ensures a minimum total annual cost. The results showed that 560 mm is the required diameter. The analysis showed also, that installing of air vessel or surge tank is must;this can be mitigated the high pressure to be less than 6 bars and controlled the magnitude of the negative pressure to safe limits. Finally, practical investigation in Salhia Agriculture Project site, Ismailia 140.9 Km2 was selected to carry out the water hammer practical investigation. The steady state calculation was first executed to measure the flow rate and the head, then the unsteady state flow calculation was carried out to identify the maximum and minimum pressure during the sudden pump trips. The results showed that:- The control devices such as the air vessels or surge tanks would mitigate the pressure rise and prevent the formation of negative pressure.- Installation of surge control device in the system such as one air vessel 50 m3 air volumes provides an acceptable level of protection to the irrigation pumping systems, as there is no cavitation at the pipeline and the maximum pressure decreases from 11 bars to 6 bars. - Water hammer analysis using AFT impulse program is an effective and reliable tool to choose the required surge protection device. Good agreement among the analytical, practical and numerical associated results was found.