Evaluation of Reductive Option of Water Hammer Phenomenon for a Water Conveyance System, A Case Study of Shahid Shirdom Residential District-Tehran

Transcription

1 : (// // )... Bentley HammerXMV:8 / / GRP. /. Bentley Hammer : Evaluation of Reductive Option of Water Hammer Phenomenon for a Water Conveyance System, A Case Study of Shahid Shirdom Residential District-Tehran K. Roshangar 1 P. Pour Heidar 2 (Received Apr. 22, 2013 Accepted Nov. 10, 2013) Abstract Sudden changes in the boundary conditions of water transmission systems, such as sudden opening and closing of valves or abrupt on and off switching of pumps and turbines cause a transient flow called water hammer. In this study, comparisons were made between the effective parameters including pipeline material, on the one hand, and the equipment and tools available for reducing the effects of water hammer, on the other. For this purpose, a practical example of a water transmission line from a pumping station located near Shahid Shirdom Residential District to the upstream reservoir in Tehran was used for modeling by the Bentley Hammer XMV: 8 software. The results obtained for the different parameters and options were compared and it was revealed that, regarding the pipe material, GRP pipes reduced pressure by 49.1 Kpa compared to the Asbestos cement pipes and by 50.3 Kpa compared to the iron pipes. Comparison of the results for the protective systems indicated that the surge tank outperformed the other alternatives in controlling pressure such that maximum pressure was reduced by 3.9 bar when using surge tanks compared to the flywheel and by 5 bar compared to the check valve. Finally, it was found that the concurrent use of the surge tank and the flywheel would be the most ideal method for controlling the water hammer effects. Keywords: Water Hammer, Surge Tanks, Flywheel, Case Study, Bentley Hammer. 1.Assist. Prof., Dept. of Civil Eng., Tabriz University, Tabriz ( ) - (Corresponding Author) roshangari@tabriz.ac.ir roshangari@tabriz.ac.ir 2. Grad. MSc Student of Hydraulic Structures, Post Graduate Studies Faculty, - Islamic Azad University, Ahar Branch, Ahar 67

2 ..[] :.[ ]..[].[]. Bentley HammerXMV: ( ) --- V 1 p fv V L 1 = + + gsinφ+ = 0 t p x 2D () -....[]..[]..[]..[].[]..[] - 4 Momentum Equations 5 Quantity Equations 1 Water Hammer 2 Transient 3 Pressure Wave 68

3 ( ).... / Bentley Hammer. /. / / (m 3 /s) /(m) / / (m/s) / - /* (m 2 /s) - p 2 V L = + pa t x 2 = 0 () t x P V ρ. φ g f a D f. f L 2 L 1.[]. L 2. a a = K ρ K 1 + E D e () e E K. L 2 L 1 L = L 1 + λl 2 L V 2 V ρ 1 ρ fv V L = λρa + + λ( + ) + g sinφ + = 0 () x t x ρλ t 2D Method of Characteristics 69

4 () L 0.5L 0.75L L /.. /.. () - () - - / / / (m/s) / / (Mpa) / / (Mpa) Bentley Hammer. GRP 1 Hazen-Williams (c) 2 Manning (n) 3 Wave Speed 4 Asbestos Cement 5 Glass fiber Reinforced Plastics () -. Bentley Hammer.. 70

5 ( ) - () ƒ= /. 71

6 () - GRP (T=2L/A). () - - () ) (Kpa) (Kpa) ( / / -/ / GRP / -/ / / -/ / GRP. GRP.[] () () () - () - 1 Check Valve 72

7 () () () - () -. :.. ( -) -/ 3 Orifice Plate () (J-11 ) - GRP GRP GRP. GRP Flywheel 2 Surge Tank 73

8 - () - -/ -/ - () / / /....( ) -/. () Cavitation 2 Surge Valve 74

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