Analysis of Attack Angle Effect on Flow Characteristics Around Torpedo-Like Geometry Placed Near the Free-Surface via CFD

Year 2021, Volume: 24 Issue: 4, 1579 - 1592, 01.12.2021

Alpaslan Kılavuz , Muammer Özgören , Tahir Durhasan , Beşir Şahin , Levent Kavurmacıoğlu , Hüseyin Akıllı , Fuad Sarığıgüzel

https://doi.org/10.2339/politeknik.675632

Cited By: 5

Abstract

In this study, the flow characteristics of torpedo-like geometry placed near the free-surface at various angles of attack were investigated numerically. The study was carried out at the Reynolds number of Re=4x104 between immersion ratios of 0.75≤h/D≤3.5 and angles of attack α=0°,4°, 8°, and 12°. Large Eddy Simulation (LES) turbulence model was used along with the Volume of Fluid (VOF) multiphase model to investigate the effects of free-surface. Wake region had an asymmetrical structure near the free-surface as a result of the interaction. A jet-like flow region was observed between the geometry and the free-surface at lower immersion ratios due to the restriction of the flow area. This flow region had a downward movement towards the lower pressure wake region. The drag coefficient, CD, values were increased with the decrease of immersion ratio. At angles of attack α=8° and 12°, the flow separation occurring near the nose caused an additional restriction in the flow area and directed the jet-like flow toward free-surface. Variation of Froude numbers (Fr) depending on the immersion ratio is examined, and it is found that Fr number and corresponding drag coefficient have higher values for the lower immersion ratio. The free-surface effect was found negligible at h/D≥2.5 for all cases.

Keywords

Computational fluid dynamics, LES, drag coefficient, free-surface, torpedo-like geometry

Supporting Institution

TÜBİTAK, ÇUKUROVA ÜNİVERSİTESİ

Project Number

214M314, FYL-2019-11596

Thanks

The authors would like to acknowledge the Scientific and Technological Research Council of Turkey (TUBITAK) under Contract No. 214M318 and Cukurova University Scientific Research Project Coordinatorship (BAP) with Contract No. FYL-2019-11596.

References

• [1] Givler, R. C., Gartling, D. K., Engelman M. S. and Haroutunian V., "Navier-Stokes simulations of flow past three-dimensional submarine models", Computer Methods in Applied Mechanics and Engineering, 87, 175-200, (1991).
• [2] Reichl, P., Hourigan, K. and Thompson, K., "The unsteady wake of a circular cylinder near a free surface", Flow Turbulence and Combustion, 71, 347-359, (2003).
• [3] Evans, J. and Nahon, M., "Dynamics modeling and performance evaluation of an autonomous underwater vehicle", Ocean Engineering, 31, 1835-1858, (2004).
• [4] Alvarez, A., Bertram, V. and Gualdesi, L., "Hull hydrodynamic optimization of autonomous underwater vehicles operating at snorkeling depth", Ocean Engineering, 36, 105-112, (2009).
• [5] Jagadeesh, P. and Murali, K., "RANS predictions of free surface effects on axisymmetric underwater body", Engineering Applications of Computational Fluid Mechanics, 4:2, 301-313, (2010).
• [6] Jagadeesh, P., Murali, K. and Idichandy, V.,”Experimental Investigation of Hydrodynamic Force Coefficients Over AUV Hull Form”, Ocean Engineering, 36 (1), 113-118, (2009).
• [7] Ozgoren M., Dogan, S., Okbaz, A., Sahin, B. and Akıllı, H., "Experimental investigation of turbulence flow structures occurred interactions between sphere and free surface ", 18. Congress on Thermal Science and Technology, Zonguldak, 141-146, (2011).
• [8] Hassanzadeh, R., Sahin, B. and Ozgoren, M., "Large eddy simulation of free-surface effects on the wake structures downstream of a spherical body", Ocean Engineering, 54, 213-222, (2012).
• [9] Dogan, S., Ozgoren M., Okbaz, A., Sahin, B. and Akilli, H., "Investigation of interactions between a sphere wake and free surface", Journal of the Faculty of Engineering and Architecture of Gazi University, 3,33, 1123-1133, (2018).
• [10] Nematollahi A., Dadvand A. and Dawoodian M., "An Axissymmetric Underwater Vehicle-Free Surface Interaction: A Numerical Study", Ocean Engineering, 96, 205-21, (2015).
• [11] Goktepeli I., Ozgoren M., Yagmur S., Kose F., Kavurmacioglu L., 2015, Numerical Flow Characteristics Investigation Around the Semi Elliptic/Elliptic Nose-Shaped Cylindrical Geometries, Congress on Thermal Science and Technology, Balıkesir, 1368-1376, (2015).
• [12] Salari, M., & Rava, A., "Numerical investigation of hydrodynamic flow over an AUV moving in the water-surface vicinity considering the laminar-turbulent transition", Journal of Marine Science and Application, 16(3), 298-304, (2017).
• [13] Javanmard, E., & Mansoorzadeh, S., "A Computational Fluid Dynamics Investigation on the Drag Coefficient Measurement of an AUV in a Towing Tank", Journal of Applied Fluid Mechanics, 12(3), 947-959, (2019).
• [14] Tian, W., Song, B., & Ding, H., "Numerical research on the influence of surface waves on the hydrodynamic performance of an AUV". Ocean Engineering, 183, 40-56, (2019).
• [15] Kilavuz, A., "Investigation of Flow Characteristics Occuring by Interactiong of Different Torpedo-Like Geometries with a Free Water Surface", MSc Thesis, Çukurova University,Institute of Natural and Applied Sciences, (2020).
• [16] Kilavuz, A., Ozgoren, M., Durhasan, T., Sahin, B., Kavurmacioglu, L., Akilli, H., Sarigiguzel, F., "Analysis of Attack Angle Effect on Flow Characteristics Around Torpedo-Like Geometry Placed Near the Free-Surface via CFD", Congress on Thermal Science and Technology, Kocaeli, 724-732, (2019).
• [17] ANSYS Inc., "Large Eddy Simulation (LES) Model", Anysys Fluent User’s Guide 6.3, (2009).
• [18] ANSYS Inc., "Volume of Fluid (VOF) Model Theory", Anysys Fluent User’s Guide 12.0, (2009).
• [19] Myring, D. F.,”A theoretical study of body drag in subcritical axisymmetric flow”, The Aeronautical Quarterly, 27(3), 186-194, (1976).
• [20] Barros, E. A., Dantas, J. L., Pascoal, A. M., & de Sá, E.,”Investigation of normal force and moment coefficients for an AUV at nonlinear angle of attack and sideslip range”, IEEE Journal of Oceanic Engineering, 33(4), 538-549, (2008).
• [21] Gao T., Wang Y., Pang Y., and J. Cao,”Hull shape optimization for autonomous underwater vehicles using CFD”, Engineering Applications of Computational Fluid Mechanics,10 (1), 599–607, (2016).
• [22] Sousa J.V.N. , Macêdo A. R. L., Amorim J.W. F. , Lima A. G. B.,”Numerical Analysis of Turbulent Fluid Flow and Drag Coefficient for Optimizing the AUV Hull Design”, Open Journal of Fluid Dynamics, 4, 263-277, (2014).
• [23] Alam K., Ray T., Anavatti S.G., 2014, “Design and construction of an autonomous underwater vehicle”, Neurocomputing, 142, 16–29, (2014). [24] ANSYS Inc., Anysys Fluent User’s Guide 12.0, (2009).
• [25] Anonymous,2020b,<https://www.simscale.com/forum/t/what-is-y-yplus/82394>,accessed: 25.05.2020.
• [26] Yagmur S, Goktepeli I., Ozgoren M., Kose F. and Kavurmacioglu L., "Numerical Investigation of Attack Angle Effect on a Torpedo-Like Geometry", 1st International Mediterranean Science and Engineering Congress, Adana, 4907-4915, (2016).
• [27] Yagmur S, Goktepeli I., Ozgoren M., Kose F. and Kavurmacioglu L., "Investigation On Hydrodynamic Characteristics of a Torpedo-Like Geometry via Different Turbulence Models and PIV", The Second Global Conference on Innovation in Marine Technology and the Future of Maritime Transportation, Bodrum, 660-673, (2016).
• [28] C. Yunus A., C. John M., “Fluid Mechanics: Fundamentals and Applications, McGraw-Hill Education, (2018).
• [29] Ahmadzadehtalatapeh M., Mousavi M., “A Review on the Drag Reduction Methods of the Ship Hulls for Improving the Hydrodynamic Performance”, International Journal of Maritime Technology, 4, 51-64, (2015).