- Volume 23 Issue 1
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Numerical and experimental study of unsteady wind loads on panels of a radar aerial
- Scarabino, Ana ;
- Sainz, Mariano Garcia ;
- Bacchi, Federico ;
- Delnero, J. Sebastian ;
- Canchero, Andres
- Received : 2015.07.04
- Accepted : 2016.05.15
- Published : 2016.07.25
This work experimentally and numerically analyzes the flow configurations and the dynamic wind loads on panels of rectangular L/h 5:1 cross section mounted on a structural frame of rectangular bars of L/h 0.5:1, corresponding to a radar structure. The fluid dynamic interaction between panels and frame wakes imposes dynamic loads on the panels, with particular frequencies and Strouhal numbers, different from those of isolated elements. The numerical scheme is validated by comparison with mean forces and velocity spectra of a panel wake obtained by wind tunnel tests. The flow configuration is analyzed through images of the numerical simulations. For a large number of panels, as in the radar array, their wakes couple in either phase or counter-phase configurations, changing the resultant forces on each panel. Instantaneous normal and tangential force coefficients are reported; their spectra show two distinct peaks, caused by the interaction of the wakes. Finally, a scaled model of a rectangular structure comprised of panels and frame elements is tested in the boundary layer wind tunnel in order to determine the influence of the velocity variation with height and the three-dimensionality of the bulk flow around the structure. Results show that the unsteady aerodynamic loads, being strongly influenced by the vortex shedding of the supporting elements and by the global 3-D geometry of the array, differ considerably on a panel in this array from loads acting on an isolated panel, not only in magnitude, but also in frequency.
wake interaction;dynamic loads;Strouhal number
- Bacchi, F., Scarabino, A., Maranon Di Leo, J., Delnero, S., Boldes, U. and Colman, J. (2007), "Numerical and experimental determination of drag coefficients and strouhal numbers of a port crane section", Proceedings of the 12th International Conference on Wind Engineering, 727-734 Cairns, Australia, July 2007.
- Bergh, H. and Tigdeman, H. (1965), "Theoretical and experimental results for the dynamic response of pressure measuring systems", National Aero- and Astronautical Research Institute Amsterdam. NLR-TR F.238.
- Blackburn, H.M., Henderson, R.D. (1999), "A study of two-dimensional flow past an oscillating cylinder", J. Fluid Mech., 385, 255-286. https://doi.org/10.1017/S0022112099004309
- Catalano, P. and Amato, M. (2003), "An evaluation of RANS turbulence modelling for aerodynamic applications", Aerosp. Sci. Technol., 7(7), 493-509. https://doi.org/10.1016/S1270-9638(03)00061-0
- Chatterjee, D., Biswas, G. and Amiroudine, S. (2010), "Numerical simulation of flow past row of square cylinders for various separation ratios", Comput. Fluids, 39(1), 49-59. https://doi.org/10.1016/j.compfluid.2009.07.002
- Fitzpatrick, J.A., Donaldson, I.S. and McKnight, W. (1988), "Strouhal numbers for flows in deep tube array models", J. Fluid. Struct., 2, 145-160. https://doi.org/10.1016/S0889-9746(88)80016-1
- Freitas, C.J. (1995), "Perspective: selected benchmarks for commercial CFD codes", J. Fluid. Eng. - T ASME, 117, 208-218. https://doi.org/10.1115/1.2817132
- Hoerner, S.F. (1965), Fluid-dynamic drag, Hoerner Fluid Dynamics.
- Holmes J.D. (2001), Wind Loading of Structures, ed. Taylor and Francis, London.
- Kaimal, J.C. and Finnigan J.J. (1994), Atmospheric Boundary Layer Flows, Oxford University Press, Oxford.
- Lam, K., Li, J.Y., Chan, K.T. and So, R.M.C. (2003), "Flow pattern and velocity field distribution of cross-flow around four cylinders in a square configuration at a low Reynolds number", J. Fluids Struct., 17, 665-679. https://doi.org/10.1016/S0889-9746(03)00005-7
- Mannini, C., Weinman, K., Soda, A. and Schewe, G. (2009), "Three-dimensional numerical simulation of flow around a 1:5 rectangular cylinder", Proceedings of the EACWE 5 Florence, Italy, 19th - 23rd July 2009.
- Menter, F.R. (1994), "Two-equation eddy-viscosity turbulence models for engineering applications", AIAA J., 32(8), 1598-1605 https://doi.org/10.2514/3.12149
- Okajima, A. (1982), "Strouhal numbers of rectangular cylinders", J. Fluid Mech., Cambridge University Press, 123, 379-398. https://doi.org/10.1017/S0022112082003115
- Sachs, P. (1978), Wind Forces in Engineering, Pergamon Press.
- Scarabino, A., Maranon di Leo, J., Delnero, J.S. and Bacchi, F. (2005), "Drag coefficients and strouhal number of a port crane boom girder section", J. Wind Eng. Ind. Aerod., 93(6), 451-460. https://doi.org/10.1016/j.jweia.2005.03.004
- So, R.M.C., Liu, Y., Chan, S.T. and Lam, K. (2001), "Numerical studies of a freely vibrating cylinder in a cross-flow", J. Fluids Struct., 15, 845-866. https://doi.org/10.1006/jfls.2000.0377
- Sumner, D., Price, S.J. and Paidoussis, M.P. (2000), "Flow-pattern identification for two staggered circular cylinders in cross flow", J. Fluid Mech., 411, 263-303. https://doi.org/10.1017/S0022112099008137
- Vikram, C.K., Krishne Gowda, Y.T. and Ravindra, H.V. (2012), "Influence of corner cutoffs on flow past square cylinder", ICCIMIM - 2012, July 2012.