Turbulent characteristics in flow subjected to bed suction and jet injection as a pier-scour countermeasure

Document Type : Research Paper

Authors

1 Department of Water Engineering, Isfahan University of Technology, Isfahan, Iran.

2 Department of Water Engineering, Isfahan University of Technology, Isfahan, Iran

3 School of Civil and Environmental Engineering, Nanyang Technological University, Singapore.

Abstract

The effect of a combined system of the bed suction and jet injection as a pier-scour countermeasure on the turbulent flow field is studied in a laboratory flume using an Acoustic Doppler Velocimeter (ADV). The three components of the velocities in the vertical symmetry plane in the equilibrium scour hole in front and rear of the pier under 3-jet injections and bed suction rate Qs/Q0 = 2%located between 0 <x/D< 2.4, (where x and D are the horizontal distance along the streamwise direction between the suction source and the pier center and the pier diameter respectively); in clear-water scour condition were measured instantaneously. Also, characteristics of turbulence flow (the turbulence intensity, vorticity and turbulent kinetic energy) in the upstream of a circular pier were investigated. The results reveal that turbulence properties, such as turbulence intensities decrease with bed suction and jet injection. Over the entire water depth, they decrease more rapidly near the bed than those near the free surface. As a result, a system of jet injection and bed suction decrease scouring around the pier.

Keywords

References

  1. Antonia R. A, Zhu Y (1995) Effect of concentrated wall suction on a turbulent boundary layer. Phys Fluids 7(10):2465-2474.
  2. Breusers H. N. C, Nicollet G, Shen H. W (1977) Local scour around cylindrical piers. J Hyd Res 15(3): 211-252.
  3. Chen X. W, Chiew, Y. M (2004) Velocity Distribution of Turbulent Open-Channel Flow with Bed Suction. J Hyd Eng 130(2):140 -148.
  4. Chen X. W, Chiew Y. M (2007) Turbulence Characteristics of Open-Channel Flow with Bed Suction. J Eng Mech 133(12):1388-1393.
  5. Chiew Y. M (1992) Scour Protection at Bridge Piers. J Hyd Eng 118 (9):1260-1269.
  6. Chiew Y. M (1995) Mechanics of riprap failure at bridge piers. J Hyd Eng 121(9):635-643.
  7. Chiew Y. M (2004) Local scour and riprap stability at bridge piers in a degrading channel. J Hyd Eng 130(3):218-226.
  8. Dey S, Mutlu Sumer B, Fredsoe J (2006) Control of Scour at Vertical Circular Piles under Waves and Current. J Hyd Eng 132(3):270-279.
  9. Dey S, Raikar V. R (2007) Clear-water scour at piers in sand beds with an armor layer of gravels. J Hyd Eng 133(6):703-711.
  10. Dey S, Sarkar A (2008) Characteristics of Submerged Jets in Evolving Scour hole Downstream of an Apron. J Eng Mech 134(11):927-936.
  11. Dey S, Nath T (2010) Turbulence characteristics in flows subjected to boundary injection and suction. J Eng Mech 136(7):877-888.
  12. Gaudio R, Tafarojnoruz A, Calomino F (2012) Combined flow-altering countermeasures against bridge pier scour. J Hyd Res 50(1):35-43.
  13. Ghodsian M, Vaghesi M (2009) Experimental study on scour and flow field in a scour hole around a T-shape spur dike in a 90° bend. Inter J Sediment Res 24(2):145-158.
  14. Grimaldi C, Gaudio R, Calomino F, Cardoso A. H (2009) Countermeasures against Local Scouring at Bridge Piers: Slot and Combined System of Slot and Bed Sill. J Hyd Eng 135(5):425-431.
  15. Lu Y, Chiew Y. M (2007) Suction effects on turbulence flows over a dune bed. J Hyd Res 45(5):691-700.
  16. Maclean A. G, Willets B. B (1986) Measurement of boundary shear stress in nonuniform open channel flow. J Hyd Res 24(1):39-51.
  17. Maclean A. G (1991) Open channel velocity profiles over a zone of rapid infiltration. J Hyd Res 29(1):15-27.
  18. Mashahir M. B, Zarrati A. R, Mokallaf E (2010) Application of Riprap and Collar to Prevent Scouring around Rectangular Bridge Piers. J Hyd Eng 136(3): 183-187.
  19. Prinos P (1995) Bed-Suction effects on Structure of Turbulent Open-Channel Flow. J Hyd Eng 121(5):404-412.
  20. Soltani-Gerdefaramarzi S, Afzalimehr H, Chiew Y. M, Lai J. S (2012a) jets to control scour around circular bridge piers. Can J Civil Eng, in press.
  21. Soltani-Gerdefaramarzi S, Afzalimehr H. Chiew Y. M, Gallichand J (2012b) Reduction of Pier scour using bed suction and jet injection. Proc Inst Civil Eng-Water Man, in press.
  22. Soltani-Gerdefaramarzi S, Afzalimehr H, Chiew Y. M (2012c) Effect of jet as a countermeasure on local pier scour. J Hyd Res. in press
  23. Tafarojnoruz A, Gaudio R, Dey S (2010) Flow-altering countermeasures against scour at bridge piers: a review. J Hyd Res 48(4):441-452.
  24. Tafarojnoruz A, Gaudio R, Calomino F (2012) Bridge Pier Scour Mitigation under Steady and Unsteady Flow Conditions. Acta Geophys 60 (4):1076-1097.
  25. Watters G. Z, Rao, M. V. P (1971) Hydrodynamic effects of seepage on bed particles. J Hyd Div 101(3):421-439.
  26. Zarrati A. M, Gholami H, Mashahir M. B (2004) Application of collar to control scouring around rectangular bridge piers. J Hyd Res 42(1):97-103.
  27. Zarrati A. M, Nazariha M, Mashahir M. B (2006) Reduction of local scour in the vicinity of bridge pier groups using collars and riprap. J Hyd Eng 132(2):154-162.
  28. Zarrati A. R, Chamani M. R, Shafaie A, Latifi M (2010) Scour countermeasures for cylindrical piers using riprap and combination of collar and riprap. Inter J Sediment Res 25(3):313-322.
  29. Schlichting H, Gersten K (2001) Boundary Layer Theory. Springer-Verlag, 8th Edition. New York.
  30. Nezu I (1977) Turbulent structure in open channel flow. PhD thesis, Kyoto University, Kyoto, Japan.
  31. Wahl T. L (2000) Analyzing ADV data using WinADV. Proc. Joint Conference on Water Resources Engineering and Water Resources Planning and Management, Minneapolis, MN, United States. 1-10.
  32. Chiew Y. M, Chen Y. Y (2008) Effect of suction on clear-water scour at bridge piers, Fourth International Conference on Scour and Erosion, Tokyo, Japan, 388-394.

Files

Share

How to cite

Statistics