Analysis of Rapid Unsteady Flow in Pipelines Using Unsteady Friction Model

Document Type : Research Paper

Authors

1 Shahid Chamran university

2 - Prof. of Hydraulic Structure Dept., Faculty of Water Sci. Eng., Shahid Chamran Univ., Ahwaz, Iran

Abstract

Analysis of unsteady flows is very important as it leads to prevent severe damage to water supply system. In the current analysis, it is assumed that the relationship between wall shear stress and mean velocity in the pipe cross-sectional area in unsteady state flow is similar to that in steady state flow. In other words, the formula expressing the wall shear stress in steady state like Darsy- Visbakh or Hazen- Williams is true for unsteady flows in each time step. Meanwhile, in the analysis of rapid unsteady flows like water hammer, wall shear stress equations in steady state are invalid because they underestimate the losses due to friction loss. Therefore, in the present study, the phenomenon of rapid unsteady flow was examined in a reservoir, pipe and valve system that consisted of 63 mm diameter polyethylene pipe with 32, 47 and 80 m lengths. Each pipe was tested with 3 discharges and immediate closing of the valve at the presence of reservoir tank with static water level of 5 meters. This hydraulic condition also was simulated by a computer model that was coded with the programming language MATLAB and was calibrated with the experimental results. This program was able to simulate the rapid unsteady flows with quasi-steady and unsteady friction models. The results indicated that the model was well able to simulate experimental results, and unsteady friction model (RMSE=0.0529) and quasi-steady friction model (RMSE=0.0858) had better estimation of unsteady state condition, respectively. Also, the laboratory pressure waves that were simulated with unsteady and quasi-steady frictional model had a faster damping in their appearance, respectively.

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References

تائبی ح، 1391. بررسی هیدرولیکی جریان­های میرا در خطوط لوله موازی با استفاده از مدل فیزیکی و عددی. رساله دکتری تخصصی، دانشکده مهندسی علوم آب دانشگاه شهید چمران اهواز.
حقیقی­پور ص، 1391. بررسی هیدرولیکی جریان­های میرا در خطوط لوله سری با استفاده از مدل فیزیکی و عددی. رساله دکتری تخصصی، دانشکده مهندسی علوم آب دانشگاه شهید چمران اهواز.
خیاط زاده ع و سامانی ح، 1376. مدل ریاضی هیدرولیکی تحلیل جریان در شبکه لوله‌ها در حالت ماندگار. پایان­نامه
کارشناسی­ارشد، دانشکده مهندسی دانشگاه شهید چمران اهواز.
 
Allievi L, 1913. The Theory of Water hammer. (Discussed by Bergant et al., 2006. Water hammer with column separation: A historical review. Journal of Fluids and Structures 22: 135-171.)
Brunone B and Golia UM, 1991. Some considerations on velocity profiles in unsteady pipe flows. Proc. Int. Conf. on Enthropy and Energy Dissipation in Water Resources, Maratea, Italy 481–487.
Brunone B, Golia UM and Greco M, 1991. Some Remarks on the Momentum Equation for Fast Transients, Proc. Int. Conf.on Hydr. Transients ith Water Column Separation, IAHR, Valencia, Spain,  201–209.
Collins RP, Boxall JB, Karney BW and Brunone B, 2012. How severe can transients be after a sudden depressurization. Journal of American Water Work Association 104(4): 67-75.
Daily JW, Hankey WL, Olive RW and Jordaan, JM, 1956. Resistance coefficients for accelerated and decelerated flows through smooth tubes and orifices. American Society of Mechanical Engineers 78(5): 1071–1077.
Fathi-Moghadam M, Haghighipour S and Mohammad Vali Samani H, 2013. Design-variable optimization of hydropower tunnels and surge tanks using a genetic algorithm. Journal of Water Resources Planning and Management 139(2): 200-208.
Ghidaoui MS, Zhao M, McInnis DA and Axworthy DH, 2005. A review of water hammer theory and practice. Journal of Applied Mechanics Reviews 58(1): 49-76.
Joukowski NE, 1898. Memoirs of the imperial academy society of St. Petersburg. Proceedings of the American Water Works Association 24: 341-424.
Meniconi S, Brunone B, and Ferrante M, 2012. Water-hammer pressure waves interaction at cross-section changes in series in viscoelastic pipes. Journal of Fluids and Structures 33: 44-58.
Parker KH and Jones CJH, 1990. Forward and backward running waves in the arteries: analysis using the method of characteristics. Journal of Biomechanical Engineering 112: 322–326.
Pothof I, 2008. A turbulent approach to unsteady friction. Journal of Hydraulic Research 46(5): 679–690.
Streeter V L and Wylie EB, 1985. Fluid Mechanics. 8th Edition, McGraw Hill, New York.
Streeter VL and Wylie EB, 1967. Hydraulic Transients. McGraw- Hill Book Co., New York.
Water and Soil Science
Volume 27, Issue 2
July 2017
Pages 157-169

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