DOI QR코드

DOI QR Code

Features of the flow over a finite length square prism on a wall at various incidence angles

  • Sohankar, A. (Department of Mechanical Engineering, Isfahan University of Technology) ;
  • Esfeh, M. Kazemi (Department of Mechanical Engineering, Isfahan University of Technology) ;
  • Pourjafari, H. (Department of Mechanical Engineering, Yazd University) ;
  • Alam, Md. Mahbub (Institute for Turbulence-Noise-Vibration Interaction and Control, Shenzhen Graduate School, Harbin Institute of Technology) ;
  • Wang, Longjun (Institute for Turbulence-Noise-Vibration Interaction and Control, Shenzhen Graduate School, Harbin Institute of Technology)
  • 투고 : 2017.09.18
  • 심사 : 2017.12.09
  • 발행 : 2018.05.25

초록

Wake characteristics of the flow over a finite square prism at different incidence angles were experimentally investigated using an open-loop wind tunnel. A finite square prism with a width D = 15 mm and a height H = 7D was vertically mounted on a horizontal flat plate. The Reynolds number was varied from $6.5{\times}10^3$ to $28.5{\times}10^3$ and the incidence angle ${\alpha}$ was changed from $0^{\circ}$ to $45^{\circ}$. The ratio of boundary layer thickness to the prism height was about ${\delta}/H=7%$. The time-averaged velocity, turbulence intensity and the vortex shedding frequency were obtained through a single-component hotwire probe. Power spectrum of the streamwise velocity fluctuations revealed that the tip and base vortices shed at the same frequency as that ofspanwise vortices. Furthermore, the results showed that the critical incidence angle corresponding to the maximum Strouhal number and minimum wake width occurs at ${\alpha}_{cr}=15^{\circ}$ which is equal to that reported for an infinite prism. There is a reduction in the size of the wake region along the height of the prism when moving away from the ground plane towards the free end.

키워드

참고문헌

  1. Alam, M.M., Zhou, Y. and Wang, X.W. (2011), "The wake of two side-by-side square cylinders", J. Fluid Mech., 669, 432-471. https://doi.org/10.1017/S0022112010005288
  2. Alam, M.M., Bai, H.L. and Zhou, Y. (2016), "The wake of two staggered square cylinders", J. Fluid Mech., 801, 475-507. https://doi.org/10.1017/jfm.2016.303
  3. Adaramola, M.S., Akinlade, O.G., Sumner, D., Bergstrom, D.J. and Schenstead, A.J. (2006), "Turbulent wake of a finite circular cylinder of small aspect ratio", J. Fluid. Struct., 22(6-7), 919-928. https://doi.org/10.1016/j.jfluidstructs.2006.04.007
  4. Bourgeois, J.A., Sattari, P. and Martinuzzib, R.J. (2011), "Alternating half-loop shedding in the turbulent wake of a finite surface-mounted square cylinder with a thin boundary layer", Phys. Fluids, 23, 095101, 1-15. https://doi.org/10.1063/1.3623463
  5. Brun, C., Aubrun S., Goossens, T. and Ravier, Ph. (2008), "Coherent structures and their frequency signature in the separated shear layer on the sides of a square cylinder", J. Flow, Turbul. Combust., 81(1-2), 97-114. https://doi.org/10.1007/s10494-008-9152-4
  6. Bruun, H.H. (1996), "Hot-wire anemometry, principles and signal analysis", OXFORD UNIVERSITY PRESS
  7. Chen, J.M. and Liu, C.H. (1999), "Vortex shedding and surface pressures on a square cylinder at Incidence to a uniform Air Stream", Int. J. Heat Fluid Fl., 20, 592-597. https://doi.org/10.1016/S0142-727X(99)00047-8
  8. Dutta, S., Muralidhar, K. and Panigrahi, P.P. (2003), "Influence of the orientation of a square cylinder on the wake properties", Exp. Fluids, 34, 16-23. https://doi.org/10.1007/s00348-002-0484-x
  9. Huang, R.F., Lin, B.H. and Yen, S.C. (2010), "Time-averaged topological flow patterns and their Influence on vortex shedding of a square cylinder in cross flow at Incidence", J. Fluid. Struct., 26(3), 406-429. https://doi.org/10.1016/j.jfluidstructs.2010.01.003
  10. Igarashi, T. (1984), "Characteristics of the flow around a square prism", Bull. JSME, 27, 1858-1865. https://doi.org/10.1299/jsme1958.27.1858
  11. Jorgenson, F. (2002), "How to measure turbulence with hot-wire anemometers" (A Practical Guide), Dantec Dynamics, Skovlunde, Denmark.
  12. Lee, B.E. (1975), "The effect of turbulence on the surface pressure field of a square prism", J. Fluid Mech., 69, 263-282. https://doi.org/10.1017/S0022112075001437
  13. Lim, H.C. Castro, I.P. and Hoxey, R.P. (2007), "Bluff bodies in deep turbulent boundary layers: Reynolds-number issues", J. Fluid Mech., 571, 97-118. https://doi.org/10.1017/S0022112006003223
  14. Lyn, D.A., Einav, S., Rodi, W. and Park, J.H. (1995), "A laserdoppler velocimetry study of ensemble-averaged characteristics of the turbulent near wake of a square cylinder", J. Fluid Mech., 304, 285-319. https://doi.org/10.1017/S0022112095004435
  15. McClean, J.F. and Sumner. D. (2014), "An experimental investigation of aspect ratio and incidence angle effects for the flow around surface-mounted finite-height square prisms", J. Fluid. Eng., 136, 081206, 1-10. https://doi.org/10.1115/1.4027138
  16. Minguez, M., Brun, C., Pasquetti, R. and Serre, E. (2011), "Experimental and high order LES analysis of the near wall flow over a square cylinder", Int. J. Heat Fluid Fl., 32(3), 558-566. https://doi.org/10.1016/j.ijheatfluidflow.2011.03.009
  17. Norberg, C. (1993), "Flow around rectangular cylinders: Pressure forces and wake frequencies", J. Wind Eng. Ind. Aerod., 49(1-3), 187-196. https://doi.org/10.1016/0167-6105(93)90014-F
  18. Obasaju, E.D. (1983), "An investigation of the effects of incidence on the flow around a square section cylinder", J. Aero. Quart., 34(11), 243-259. https://doi.org/10.1017/S0001925900009768
  19. Okajima, A. (1982), "Strouhal numbers of rectangular cylinders", J. Fluid Mech., 123, 379-398. https://doi.org/10.1017/S0022112082003115
  20. Okamoto, H., and Sunabashiri, Y. (1992), "Vortex shedding from a circular cylinder of finite length placed on a ground plane", J. Fluids Eng., 114(4), 512-521. https://doi.org/10.1115/1.2910062
  21. Oudheusden, B.W.V., Scarano, F., Hinsberg, N.P.V. and Roosenboom, E.W.M. (2008), "Quantitative visualization of the flow around a square-section cylinder at incidence", J. Wind Eng. Ind. Aerod., 96(6-7), 913-922. https://doi.org/10.1016/j.jweia.2007.06.030
  22. Park, C.W. and Lee, S.J. (2000), "Free end effects on the near wake flow structure behind a finite circular cylinder", J. Wind Eng. Ind. Aerod., 88(2-3), 231-246. https://doi.org/10.1016/S0167-6105(00)00051-9
  23. Rastan, M.R., Sohankar, A. and Alam, M.M. (2017), "Low-Reynolds-number flow around a wall-mounted square cylinder: flow structures and onset of vortex shedding", Phys. Fluids, 29, 103601, 1-19. https://doi.org/10.1063/1.4989745
  24. Rockwell, D.O. (1977), "Organized fluctuations due to flow past a square cross section cylinder", J. Fluids Eng., 99(3), 511-516. https://doi.org/10.1115/1.3448831
  25. Sakamoto, H. and Arie, M. (1983), "Vortex shedding from a rectangular prism and a circular cylinder placed vertically in a turbulent boundary layer", J. Fluid Mech., 126, 147-165. https://doi.org/10.1017/S0022112083000087
  26. Sakamoto, H. (1985), "Aerodynamic forces acting on a rectangular prism placed vertically in a turbulent boundary layer", J. Wind Eng. Ind. Aerod., 18(2), 131-151. https://doi.org/10.1016/0167-6105(85)90093-5
  27. Sarode, R.S., Gai, S.L. and Ramesh, C.K. (1981), "Flow around circular-and square-section models of finite height in a turbulent shear flow", J. Wind Eng. Ind. Aerod., 8(3), 223-230. https://doi.org/10.1016/0167-6105(81)90022-2
  28. Sohankar, A., Norberg, C. and Davidson, L. (1998), "Low-Reynolds number flow around a square cylinder at incidence: Study of blockage, onset of vortex shedding and outlet boundary condition", Int. J. Numer. Meth. Fl., 26, 39-56. https://doi.org/10.1002/(SICI)1097-0363(19980115)26:1<39::AID-FLD623>3.0.CO;2-P
  29. Sohankar, A., Norberg, C. and Davidson, L. (1999), "Simulation of unsteady 3D flow around a square cylinder at moderate Reynolds number", Phys. Fluids, 11(2), 288-306. https://doi.org/10.1063/1.869879
  30. Sohankar, A., Davidson, L. and Norbeg, C. (2000), "Large eddy simulation of flow past a square cylinder: comparison of different subgrid scale models", J. Fluid. Eng., 122(1), 39-47. https://doi.org/10.1115/1.483224
  31. Sohankar, A. (2006), "Flow over a bluff body from moderate to high Reynolds numbers using large eddy simulation", Comput. Fluids, 35(10), 1154-1168. https://doi.org/10.1016/j.compfluid.2005.05.007
  32. Sohankar, A. (2008), "Large eddy simulation of flow past rectangular section cylinders: Side ratio effects", J. Wind Eng. Ind. Aerod., 96(5), 640-655. https://doi.org/10.1016/j.jweia.2008.02.009
  33. Sohankar, A., Mohagheghian, S., Dehghan, A.A. and Dehghan Manshadi, M. (2015), "A smoke visualization study of the flow over a square cylinder at incidence and tandem square cylinders", J. Visualization, 18(4), 687-703. https://doi.org/10.1007/s12650-015-0275-0
  34. Sumner, D., Heseltine, J.L. and Dansereau, O.J.P. (2004), "Wake structure of a finite circular cylinder of small aspect ratio", Exp. Fluids, 37(5), 720-730. https://doi.org/10.1007/s00348-004-0862-7
  35. Trias, F.X. Gorobets, A. and Oliva A. (2015). "Turbulent flow around a square cylinder at Reynolds number 22,000: A DNS study", Comput. Fluids, 123 (22), 87-98. https://doi.org/10.1016/j.compfluid.2015.09.013
  36. Wang, H.F., Zhou, Y., Chan, C.K., Wong, W.O. and Lam., K.S. (2004) "Flow structure around a finite length square prism", Proceedings of the 15th Australasian Fluid Mechanics Conference, The University of Sydney, Sydney, Australia.
  37. Wang, H.F., Zhou, Y., Chan, C.K. and Lam, K.S. (2006), "Effect of initial conditions on interaction between a boundary layer and a wall-mounted finite-length-cylinder wake", Phys. Fluids, 18, 065106, 1-12. https://doi.org/10.1063/1.2212329
  38. Wang, H.F. and Zhou, Y. (2009), "The finite-length square cylinder near wake", J. Fluid Mech., 638, 453-490. https://doi.org/10.1017/S0022112009990693
  39. West, G.S. and Apelt, C.J. (1982), "The effects of tunnel blockage and aspect ratio on the mean flow past a circular cylinder with Reynolds numbers between 104 and 105", J. Fluid Mech., 114, 361-377. https://doi.org/10.1017/S0022112082000202
  40. Williamson C.H.K. (1996), "Three-dimensional wake transition", J. Fluid Mech., 328, 345-407. https://doi.org/10.1017/S0022112096008750
  41. Yavuzkurt, S. (1984), "A guide to uncertainty analysis of hot-wire data", J. Fluid. Eng., 106(2), 181-186. https://doi.org/10.1115/1.3243096
  42. Yen, S.C. and Yang, C.W. (2011), "Flow patterns and vortex shedding behavior behind a square cylinder", J. Wind Eng. Ind. Aerod., 99(8), 868-878. https://doi.org/10.1016/j.jweia.2011.06.006
  43. Yen, S.C. and Yang, C.W. (2012), "Characteristic flow field behind a square-cylinder using upstream mesh fences", J. Fluid. Eng., 134(9), 091202-1-9. https://doi.org/10.1115/1.4004904
  44. Zdravkovich, M.M. (2003), "Flow around circular cylinders", 2, Applications. Oxford University Press.
  45. Zheng, Q.M. and Alam, M.M. (2017), "Intrinsic features of flow past three square prisms in side-by-side arrangement", J. Fluid Mech., 826, 996-1033. https://doi.org/10.1017/jfm.2017.378