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Vortical structures in the near wake of tabs with various geometries

  • A. M. Hamed (a1), A. Pagan-Vazquez (a1), D. Khovalyg (a1), Z. Zhang (a1) and L. P. Chamorro (a1) (a2) (a3)...
Abstract

The vortical structures and turbulence statistics in the near wake of rectangular, trapezoidal, triangular and ellipsoidal tabs were experimentally studied in a refractive-index-matching channel. The tabs share the same bulk dimensions, including a 17 mm height, a 28 mm base width and a $24.5^{\circ }$ inclination angle. Measurements were performed at two Reynolds numbers based on the tab height, $Re_{h}\simeq 2000$ (laminar incoming flow) and 13 000 (turbulent incoming flow). Three-dimensional, three-component particle image velocimetry (PIV) was used to study the mean flow distribution and dominant large-scale vortices, while complementary high-spatial-resolution planar PIV measurements were used to quantify high-order statistics. Instantaneous three-dimensional fields revealed the coexistence of a coherent counter-rotating vortex pair (CVP) and hairpin structures. The CVP and hairpin vortices (the primary structures) exhibit distinctive characteristics and strength across $Re_{h}$ and tab geometries. The CVP is coherently present in the mean flow field and grows in strength over a significantly longer distance at the low $Re_{h}$ due to the lower turbulence levels and the delayed shedding of the hairpin vortices. These features at the low $Re_{h}$ are associated with the presence of Kelvin–Helmholtz instability that develops over three tab heights downstream of the trailing edge. Moreover, a secondary CVP with an opposite sense of rotation resides below the primary one for the four tabs at the low $Re_{h}$ . The interaction between the hairpin structures and the primary CVP is experimentally measured in three dimensions and shows complex coexistence. Although the CVP undergoes deformation and splitting at times, it maintains its presence and leads to significant mean spanwise and wall-normal flows.

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Corresponding author
Email address for correspondence: lpchamo@illinois.edu
References
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Bai, K. & Katz, J. 2014 On the refractive index of sodium iodide solutions for index matching in piv. Exp. Fluids 55, 16.
Blois, G., Christensen, K. T., Best, J. L., Elliott, G., Austin, J., Dutton, C., Bragg, M., Garcia, M. & Fouke, B. 2012 A versatile refractive-index-matched flow facility for studies of complex flow systems across scientific disciplines. In 50th American Institute of Aeronautics and Astronautics (AIAA) Aerospace Sciences Meeting, Nashville, TN, AIAA, AIAA 2012-0736, doi:10.2514/6.2012-736.
Calderon, D. E., Wang, Z., Gursul, I. & Visbal, M. R. 2013 Volumetric measurements and simulations of the vortex structures generated by low aspect ratio plunging wings. Phys. Fluids 25 (6), 067102.
Cambonie, T., Gautier, N. & Aider, J.-L. 2013 Experimental study of counter-rotating vortex pair trajectories induced by a round jet in cross-flow at low velocity ratios. Exp. Fluids 54 (3), 113.
Chamorro, L. P., Troolin, D. R., Lee, S., Arndt, R. E. A. & Sotiropoulos, F. 2013 Three-dimensional flow visualization in the wake of a miniature axial-flow hydrokinetic turbine. Exp. Fluids 54 (2), 112.
Cheng, B., Sane, S. P., Barbera, G., Troolin, D. R., Strand, T. & Deng, X. 2013 Three-dimensional flow visualization and vorticity dynamics in revolving wings. Exp. Fluids 54 (1), 112.
Chua, L., Yu, S. & Wang, X. 2003 Flow visualization and measurements of a square jet with mixing tabs. Exp. Therm. Fluid Sci. 27 (6), 731744.
Dong, S. & Meng, H. 2004 Flow past a trapezoidal tab. J. Fluid. Mech. 510, 219242.
Elavarasan, R. & Meng, H. 2000 Flow visualization study of role of coherent structures in a tab wake. Fluid Dyn. Res. 27 (3), 183197.
Gad-elhak, M. 2000 Flow Control: Passive, Active and Reactive Flow Management. Cambridge University Press.
Ghanem, A., Habchi, C., Lemenand, T., Della Valle, D. & Peerhossaini, H. 2013 Energy efficiency in process industry – high-efficiency vortex (HEV) multifunctional heat exchanger. J. Renew. Energy 56, 96104.
Ghanem, A., Lemenand, T., Della Valle, D., Habchi, C. & Peerhossaini, H. 2012 Vortically enhanced heat transfer and mixing: state of the art and recent results. In ASME 2012 Heat Transfer Summer Conference, pp. 2130. American Society of Mechanical Engineers.
Gretta, W. J.1990 An exsperimental study of the fluid mixing effects and flow structure due to surface mounted passive vortex generating device. Master’s thesis, Lehigh University, Bethlehem, PA, USA.
Gretta, W. J. & Smith, C. R. 1993 Flow structure and statistics of a passive mixing tab. Trans. ASME 115 (2), 255263.
Habchi, C., Lemenand, T., Della Valle, D. & Peerhossaini, H. 2010a Alternating mixing tabs in multifunctional heat exchanger-reactor. Chem. Engng Process. 49 (7), 653661.
Habchi, C., Lemenand, T., Valle, D. & Peerhossaini, H. 2010b Turbulence behavior of artificially generated vorticity. J. Turbul. 11 (36), 128.
Hamed, A. M., Kamdar, A., Castillo, L. & Chamorro, L. P. 2015 Turbulent boundary layer over 2D and 3D large-scale wavy walls. Phys. Fluids 27 (10), 106601.
Hunt, J. C. R., Wray, A. A. & Moin, P.1988 Eddies, streams, and convergence zones in turbulent flows. Center for Turbulence Research Report CTR-S88, p. 193.
Jeong, J. & Hussain, F. 1995 On the identification of a vortex. J. Fluid Mech. 285, 6994.
Kaci, H. M., Habchi, C., Lemenand, T., Della Valle, D. & Peerhossaini, H. 2010 Flow structure and heat transfer induced by embedded vorticity. Intl J. Heat Mass Transfer 53 (17), 35753584.
Lögdberg, O., Fransson, J. H. M. & Alfredsson, P. H. 2009 Streamwise evolution of longitudinal vortices in a turbulent boundary layer. J. Fluid Mech. 623, 2758.
Moriconi, L. 2009 Minimalist turbulent boundary layer model. Phys. Rev. E 79 (4), 046306.
Park, J., Pagan-Vazquez, A., Alvarado, J. L., Chamorro, L. P., Lux, S. & Marsh, C. 2016 Experimental and numerical visualization of counter rotating vortices. J. Heat Transfer 138 (8), 080908.
Pereira, F. & Gharib, M. 2002 Defocusing digital particle image velocimetry and the three-dimensional characterization of two-phase flows. Meas. Sci. Tech. 13, 683694.
Pereira, F., Gharib, M., Dabiri, D. & Modarress, D. 2000 Defocusing digital particle image velocimetry: a 3-component 3-dimensional DPIV measurement technique. Application to bubbly flows. Exp. Fluids 29, S078S084.
Reeder, M. & Samimy, M. 1996 The evolution of a jet with vortex-generating tabs: real-time visualization and quantitative measurements. J. Fluid Mech. 311, 73118.
Sharp, K., Hill, D., Troolin, D., Walters, G. & Lai, W. 2010 Volumetric 3-component velocimetry measurements of the turbulent flow around a Rushton turbine. Exp. Fluids 48 (1), 167183.
Stephens, A. V. & Collins, G. A.1955 Turbulent boundary layer control by ramps or wedges. Australian Aeronautical Research Committee – Report p. 19.
Sun, Z., Schrijer, F. F. J., Scarano, F. & Van Oudheusden, B. W. 2012 The three-dimensional flow organization past a micro-ramp in a supersonic boundary layer. Phys. Fluids 24 (5), 055105.
Troolin, D. & Longmire, E. K. 2009 Volumetric velocity measurements of vortex rings from inclined exits. Exp. Fluids 48 (3), 409420.
Wu, Y. & Christensen, K. T. 2006 Population trends of spanwise vortices in wall turbulence. J. Fluid Mech. 568 (1), 5576.
Yang, W., Meng, H. & Sheng, J. 2001 Dynamics of hairpin vortices generated by a mixing tab in a channel flow. Exp. Fluids 30 (6), 705722.
Ye, Q., Schrijer, F. F. J. & Scarano, F. 2016 Boundary layer transition mechanisms behind a micro-ramp. J. Fluid Mech. 793, 132161.
Yu, Y., Zhang, J. & Shan, Y. 2015 Convective heat transfer of a row of air jets impingement excited by triangular tabs in a confined crossflow channel. Intl J. Heat Mass Transfer 80, 126138.
Zaman, K., Reeder, M. & Samimy, M. 1994 Control of an axisymmetric jet using vortex generators. Phys. Fluids 6 (2), 778793.
Zhou, J., Adrian, R. J., Balachandar, S. & Kendall, T. M. 1999 Mechanisms for generating coherent packets of hairpin vortices in channel flow. J. Fluid Mech. 387, 353396.
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Journal of Fluid Mechanics
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  • EISSN: 1469-7645
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