Wind and Structures

Techno-Press (테크노프레스)
권호 표지
DOI QR코드

DOI QR Code

Unsteady galloping of sharp-edged bluff bodies: experimental observations on the effect of the wind angle of attack

  • Chen, Cong (Institute of Steel Structures, Technische Universität Braunschweig) ;
  • Dai, Bingyu (Zhejiang Province Institute of Architectural Design and Research (ZIAD)) ;
  • Wieczorek, Niccolo (Institute of Steel Structures, Technische Universität Braunschweig) ;
  • Unglaub, Julian (Institute of Steel Structures, Technische Universität Braunschweig) ;
  • Thiele, Klaus (Institute of Steel Structures, Technische Universität Braunschweig)
  • Received : 2022.05.11
  • Accepted : 2022.10.02
  • Published : 2022.10.25
⟨ Previous Next ⟩

Abstract

Light-weight or low-damped structures may encounter the unsteady galloping instability that occurs at low reduced wind speeds, where the classical quasi-steady assumption is invalid. Although this unsteady phenomenon has been widely studied for rectangular cross sections with one side perpendicular to the incidence flow, the effect of the mean wind angle of attack has not been paid enough attention yet. With four sectional models of different side ratios and geometric shapes, the presented research focuses on the effect of the wind angle of attack on unsteady galloping instability. In static tests, comparatively strong vortex shedding force was noticed in the middle of the range of flow incidence where the lift coefficient shows a negative slope. In aeroelastic tests with a low Scruton number, the typical unsteady galloping, which is due to an interaction with vortex-induced vibration and results in unrestricted oscillation initiating at the Kármán vortex resonance wind speed, was observed for the wind angles of attack that characterize relatively strong vortex shedding force. In contrast, for the wind angles of attack with relatively weak shedding force, an "atypical" unsteady galloping was found to occur at a reduced wind speed clearly higher than the Kármán-vortex resonance one. These observations are valid for all four wind tunnel models. One of the wind tunnel models (with a bridge deck cross section) was also tested in a turbulent flow with an intensity about 9%, showing only the atypical unsteady galloping. However, the wind angle of attack with the comparatively strong vortex shedding force remains the most unfavorable one with respect to the instability threshold in low Scruton number conditions.

Keywords

Acknowledgement

The first author wishes to thank the China Scholarship Council (CSC) for the funding support (No.201506260188).

References

  1. Bearman, P., Gartshore, I., Maull, D. and Parkinson, G. (1987), "Experiments on flow-induced vibration of a square-section cylinder", J. Fluid. Struct., 1(1), 19-34. https://doi.org/10.1016/S0889-9746(87)90158-7.
  2. Carassale, L., Freda, A. and Banfi, L. (2015), "Motion-excited forces acting on a square prism: a qualitative analysis", Proceedings of the 14th International Conference on Wind Engineering, Porto Alegre, Brazil, June.
  3. Chen, C. (2021), "Unsteady galloping of bridge deck during the launching phase", Ph.D. Dissertation, University of Florence - Technische Universitat Braunschweig, Florence (Italy) & Braunschweig (Germany).
  4. Chen, C., Mannini, C., Bartoli, G. and Thiele, K. (2020), "Experimental study and mathematical modeling on the unsteady galloping of a bridge deck with open cross section", J. Wind Eng. Ind. Aerod., 203, 104170. https://doi.org/10.1016/j.jweia.2020.104170.
  5. Chen, C., Mannini, C., Bartoli, G. and Thiele, K. (2022), "Wake oscillator modeling the combined instability of vortex induced vibration and galloping for a 2: 1 rectangular cylinder", J. Fluid. Struct., 110, 103530. https://doi.org/10.1016/j.jfluidstructs.2022.103530.
  6. Chen, C., Wieczorek, N., Unglaub, J. and Thiele, K. (2021), "Extension of wake oscillator model for continuous system and application to the VIV-galloping instability of a bridge during launching phase", J. Wind Eng. Ind. Aerod., 218, 104769. https://doi.org/10.1016/j.jweia.2021.104769.
  7. Corless, R.M. and Parkinson, G. (1988), "A model of the combined effects of vortex-induced oscillation and galloping", J. Fluid. Struct., 2(3), 203-220. https://doi.org/10.1016/S0889-9746(88)80008-2.
  8. Dai, B. (2019), "Experimental investigation on the aeroelastic galloping instability of a square cylinder", Master's thesis, Technische Universitat Braunschweig, Braunschweig, Germany.
  9. Den Hartog, J. (1932), "Transmission line vibration due to sleet", T. Am. Inst. Electr. Eng., 51(4), 1074-1076. https://doi.org/10.1109/T-AIEE.1932.5056223.
  10. EN 1991-1-4 (2010), Eurocode 1-actions on structures-part 1-4: General actions-wind actions.
  11. Gao, G. and Zhu, L. (2016), "Measurement and verification of unsteady galloping force on a rectangular 2: 1 cylinder", J. Wind Eng. Ind. Aerod., 157, 76-94. https://doi.org/10.1016/j.jweia.2016.08.004.
  12. Gao, G., Zhu, L., Li, J. and Han, W. (2020), "Modelling nonlinear aerodynamic damping during transverse aerodynamic instabilities for slender rectangular prisms with typical side ratios", J. Wind Eng. Ind. Aerod., 197, 104064. https://doi.org/10.1016/j.jweia.2019.104064.
  13. Hemon, P. (2012), "Large galloping oscillations of a square section cylinder in wind tunnel", Proceedings of the 10th International Conference on Flow-Induced Vibration (& Flow- Induced Noise), Dublin, Ireland, July.
  14. Hemon, P. and Santi, F. (2002), "On the aeroelastic behaviour of rectangular cylinders in cross-flow", J. Fluid. Struct., 16(7), 855-889. https://doi.org/10.1006/jfls.2002.0452.
  15. Itoh, Y. and Tamura, T. (2002), "The role of separated shear layers in unstable oscillations of a rectangular cylinder around a resonant velocity", J. Wind Eng. Ind. Aerod., 90(4-5), 377-394. https://doi.org/10.1016/S0167-6105(01)00208-2.
  16. Lee, B. (1974), "The surface pressure field experienced by a twodimensional square prism", Technical Report RD/L/NI7/74,
  17. Central Electricity Research Laboratories, Leatherhead, England. Liu, Y., Ma, C., Li, Q., Yan, B. and Liao, H. (2018), "A new modeling approach for transversely oscillating square-section cylinders", J. Fluid. Struct., 81, 492-513. https://doi.org/10.1016/j.jfluidstructs.2018.05.014.
  18. Luo, S., Chew, Y., Lee, T. and Yazdani, M. (1998), "Stability to translational galloping vibration of cylinders at different mean angles of attack", J. Sound Vib., 215(5), 1183-1194. https://doi.org/10.1006/jsvi.1998.1639.
  19. Luo, S., Yazdani, M.G., Chew, Y. and Lee, T. (1994), "Effects of incidence and afterbody shape on flow past bluff cylinders", J. Wind Eng. Ind. Aerod., 53(3), 375-399. https://doi.org/10.1016/0167-6105(94)90092-2.
  20. Ma, C., Liu, Y., Li, Q. and Liao, H. (2018), "Prediction and explanation of the aeroelastic behavior of a square-section cylinder via forced vibration", J. Wind Eng. Ind. Aerod., 176, 78-86. https://doi.org/10.1016/j.jweia.2018.03.007.
  21. Mannini, C. (2020a), "Asymptotic analysis of a dynamical system for vortex-induced vibration and galloping", in Lacarbonara, W. et al. (Eds.), Nonlinear Dynamics of Structures, Systems and Devices, Springer, Cham, Switzerland, 389-397. https://doi.org/10.1007/978-3-030-34713-0_39.
  22. Mannini, C. (2020b), "Incorporation of turbulence in a nonlinear wake-oscillator model for the prediction of unsteady galloping response", J. Wind Eng. Ind. Aerod., 200, 104141. https://doi.org/10.1016/j.jweia.2020.104141.
  23. Mannini, C., Marra, A.M. and Bartoli, G. (2014), "VIV-galloping instability of rectangular cylinders: Review and new experiments", J. Wind Eng. Ind. Aerod., 132, 109-124. https://doi.org/10.1016/j.jweia.2014.06.021.
  24. Mannini, C., Marra, A.M., Massai, T. and Bartoli, G. (2016), "Interference of vortex-induced vibration and transverse galloping for a rectangular cylinder", J. Fluid. Struct., 66, 403-423. https://doi.org/10.1016/j.jfluidstructs.2016.08.002.
  25. Mannini, C., Massai, T. and Marra, A.M. (2018a), "Modeling the interference of vortex-induced vibration and galloping for a slender rectangular prism", J. Sound Vib., 419, 493-509. https://doi.org/10.1016/j.jsv.2017.12.016.
  26. Mannini, C., Massai, T. and Marra, A.M. (2018b), "Unsteady galloping of a rectangular cylinder in turbulent flow", J. Wind Eng. Ind. Aerod., 173, 210-226. https://doi.org/10.1016/j.jweia.2017.11.010.
  27. Matsumoto, M., Ishizaki, H., Matsuoka, C., Daito, Y., Ichikawa, Y. and Shimahara, A. (1998), "Aerodynamic effects of the angle of attack on a rectangular prism", J. Wind Eng. Ind. Aerod., 77, 531-542. https://doi.org/10.1016/S0167-6105(98)00170-6.
  28. Nakamura, Y. and Mizota, T. (1975), "Unsteady lifts and wakes of oscillating rectangular prisms", J. Eng. Mech. Div., 101(6), 855-871. https://doi.org/10.1061/JMCEA3.0002077.
  29. Nguyen, C.H., Macdonald, J.H. and Cammelli, S. (2020), "Nonacross-wind galloping of a square-section cylinder", Meccanica, 55(6), 1333-1345. https://doi.org/10.1007/s11012-020-01166-6.
  30. Niu, H., Zhou, S., Chen, Z. and Hua, X. (2015), "An empirical model for amplitude prediction on VIV-galloping instability of rectangular cylinders", Wind Struct., 21(1), 85-103. https://doi.org/10.12989/was.2015.21.1.085.
  31. Obasaju, E. (1979), "On the effects of end plates on the mean forces on square sectioned cylinders", J. Wind Eng. Ind. Aerod., 5(1-2), 179-186. https://doi.org/10.1016/0167-6105(79)90030-8.
  32. Otsuki, Y., Washizu, K., Tomizawa, H., Ohya, A. and Fujii, K. (1971), "Experiments on the aeroelastic instability of prismatic bars with rectangular sections", Proceedings of the 3rd International Conference on Wind Effects on Buildings and Structures, Tokyo, Japan, September.
  33. Parkinson, G. (1965), "Aeroelastic galloping in one degree of freedom", Wind Effects on Buildings and Structures: Proceedings of the Conference held at the National Physical Laboratory, Teddington, UK, June.
  34. Parkinson, G. and Brooks, N. (1961), "On the aeroelastic instability of bluff cylinders", J. Appl. Mech., 28(1), 252-258. https://doi.org/10.1115/1.3641663.
  35. Roach, P.E. (1987), "The generation of nearly isotropic turbulence by means of grids", Intl J. Heat Fluid Fl., 8(2), 82-92. https://doi.org/10.1016/0142-727X(87)90001-4.
  36. Slater, J.E. (1969), "Aeroelastic instability of a structural angle section", Ph.D. Dissertation. University of British Columbia, Vancouver, Canada.
  37. Tamura, Y. and Shimada, K. (1987), "A mathematical model for the transverse oscillations of square cylinders", Proceedings of International Conference on Flow Induced Vibrations, Bowness-Windermere, UK, May.
  38. Von Karman, T. (1948), "Progress in the statistical theory of turbulence", Proc. Natl. Acad. Sci., 34(11), 530-539. https://doi.org/10.1073/pnas.34.11.530.
  39. Washizu, K., Ohya, A., Otsuki, Y. and Fujii, K. (1978), "Aeroelastic instability of rectangular cylinders in a heaving mode", J. Sound Vib., 59(2), 195-210. https://doi.org/10.1016/0022-460X(78)90500-X.
  40. Wawzonek, M.A. (1979), "Aeroelastic behavior of square section prisms in uniform flow", Master's thesis. University of British Columbia, Vancouver, Canada.