بررسی اثر مکان کنترل‌کننده‌‌های جریان برکاهش گردابه‌های اطراف استوانه

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی کارشناسی ارشد، دانشگاه جامع امام حسین (ع)، تهران، ایران

2 دکترا، دانشگاه جامع امام حسین (ع)، تهران، ایران

چکیده

کنترل جریان روی استوانه و به تعویق انداختن ناحیه‌ی جدایش جریان از سطح استوانه، باعث کوچک شدن ناحیه‌ی دنباله و کاهش ریزش گردابه‌ها می‌گردد و عمر سازه را افزایش می‌دهد. پدیده‌ی خستگی که در اثر بارگذاری و تنش‌های نوسانی وارد بر سازه‌ها ایجاد می‌شود، موجب استهلاک و کاهش عمر سازه‌ها می‌گردد. کنترل‌کننده‌های جریان نقش بازدارنده در ایجاد پدیده‌ی خستگی دارند. در این پژوهش تأثیر دو استوانه‌ی کنترلی برای فواصل مختلف از استوانه اصلی در رینولدز 140 مورد ارزیابی قرار ‌گرفت. یافتن فاصله‌ی خاصی برای جای‌گیری استوانه‌‌های کنترلی از استوانه‌ی اصلی که در آن فاصله‌ ریزش گردابه‌ها تا حد مطلوبی کاهش یافته و خنثی شود، هدف اصلی این پژوهش است. بدین منظور تحلیل عددی گذرا توسط نرم‌افزار فلوئنت انجام شد. نتایج این پژوهش حاکی از آن است که فاصله‌ی خاصی برای خنثی‌سازی ریزش گردابه‌ها وجود دارد. این فاصله، برای رینولدز 140 به اندازه‌ی 0.8 قطر استوانه‌ی اصلی است و از آن تحت عنوان فاصله‌ی طلایی می‌توان یاد کرد که مؤلفه‌ی مهمی در طراحی به حساب می‌آید.

کلیدواژه‌ها


عنوان مقاله [English]

Investigating the effect of the location of flow controllers on the reduction of vortices around the cylinder

نویسندگان [English]

  • Mojtaba Barzegar Rahimi 1
  • Amin Jalalian 2
1 Master's student, Imam Hossein University (AS), Tehran, Iran
2 Ph.D., Imam Hossein University (AS), Tehran, Iran
چکیده [English]

Controlling the flow on the cylinder and postponing the flow separation area from the surface of the cylinder, Shrinking the wake area and reduces the drop of vortices and increases the life of the structure. The phenomenon of fatigue, which is caused by loading and fluctuating stresses on the structures, causes depreciation and reduces the life of the structures. Flow controllers play an inhibitory role in creating the phenomenon of fatigue. In this research, the effect of two control cylinders for different distances from the main cylinder at Reynolds 140 was evaluated. The main goal of this research is to find a certain distance to place the control cylinders from the main cylinder in which the vortex shedding distance is reduced to an optimal level and neutralized. For this purpose, transient numerical analysis was performed by Fluent software. The results of this research indicate that there is a certain distance to neutralize the fall of vortices. This distance, for Reynolds 140, is equal to 0.8 of the diameter of the main cylinder, and it can be referred to as the golden distance, which is considered an important component in the design.

کلیدواژه‌ها [English]

  • Flow controllers
  • Flow around cylinder
  • Vortex shedding
  • Numerical simulation
  • Von-Karman vortex

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1. Goodarzi, M., and Khalili Dehkordi, E., “Numerical Study on Laminar Flow Over a Cylinder and Its Rotating Controllers for Suppressing the Vortex Shedding”, Amirkabir J. Mech. Eng., No. 50(4), pp.849-862, 2018, (In Persian).
2. Newman, J. N., “Marine Hydrodynamics”, The MIT Press Cambridge and Massachusetts, 1999.
3. Asyikin, M. T., “CFD Simulation of Vortex Induced Vibration of a Cylindrical Structure”, MSc thesis, Institutt for bygg, anlegg og transport, 2012.
4. Blevins, R. D., “Flow-Induced Vibration”, 2 ed., New York, NY: Van Nostrand Reinhold, 1990.
5. Barzegar Rahimi, M., Amanifard, N., and Samaei, L., “Numerical Study of Flow Control Around Circular Cylinder by Using Two Other Control Cylinders”, 19th Fluid Dynamics Conference, Tehran, 2021, (In Persian).
6. Kuo, C. H., Chiou, L. C., and Chen, C. C., “Wake Flow Pattern Modified by Small Control Cylinders at Low Reynolds Number”, Journal of Fluids and Structures, No. 23, pp. 938–956, 2007.
7. Darekar, R.M., and Sherwin, S.J., “Flow Past a Bluff Body With a Wavy Stagnation Face”, Journal of Fluids and Structures, No. 15, pp.587-596, 2001.
8. Rashidi, S., Hayadavoodi, M., and Esfahani, J.A., “Vortex Shedding Suppression and Wake Control: a Review”, J. OCEAN ENG., No. 126, pp.57-80, 2016.
9. Meneghini, J. R., Saltara, F., Siqueira, C. L. R., and Ferrari, J. A., “Numerical Simulation of Flow Interference between Two Circular Cylinders in Tandem and Side-By-Side Arrangements”, Journal of Fluids and Structures, No. 15, pp.327-350, 2001.
10. Wang, Y. T., Yan, Z. M., and Wang, H. M., “Numerical simulation of low-Reynolds number flows past two tandem cylinders of different diameters”, J. Water Science and Engineering, Vol. 6, No. 4, pp.433-445, 2013.
11. Williamson, C. H. K., “Oblique and Parallel Modes of Vortex Shedding in The Wake of a Circular Cylinder at Low Reynolds Numbers”, J. Journal of Fluid Mechanics, No. 206, pp.579-627, 1989.
12. Badr, H.M., Coutanceau, M., Dennis, S.C.R., and Menard, C., “Unsteady Flow Past a Rotating Cylinder at Reynolds Numbers 103 and 104”, Journal of Fluid Mechanics, No. 220, pp.459-484, 1990.
13. Maurel, A., and Petitjeans, P., “Vortex Structure and Dynamics”, Lectures of a Workshop Held in Rouen, France, Springer, 1999.
14. Brocchini, M., and Trivellato, F., “Vorticity and Turbulence Effects in Fluid Structure Interaction”, An application to hydraulic structure design, WIT press, 2006.
15. Drazin, P. G., “Introduction to Hydrodynamic Stability”, Cambridge University Press, 2002.
16. Blevins, R. D., “Flow Induced Vibration”, Krieger, 2001.
17. Paidoussis, M. P., “Fluid Structure Interactions, Slender Structures and Axial Flow”, Vol. 1, Academic Press, 1999.
18. Paidoussis, M. P., “Fluid Structure Interactions, Slender Structures and Axial Flow”, Vol. 2, Elsevier, 2004.
19. Zhang, X., Choi, K. S., Huang, Y., and Li, H. X., “Flow control over a circular cylinder using virtual moving surface boundary layer control”, Experiments in fluids, Vol. 60, No. 6, pp.1-15, 2019.‏
20. Imron, C., Hakam, A., Widodo, B., and Yuwono, T. Y., “Numerical Simulation of Fluid Flow Around Circular Cylinder and Three Passive Controls to Reduce Drag Coefficient at Re= 500”,  IJCSAM, Vol. 6, No.1, pp.13-17, 2020.‏
21. Han, X., Wang, J., Zhou, B., Zhang, G., and Tan, S. K., “Numerical simulation of flow control around a circular cylinder by installing a wedge-shaped device upstream”, Journal of Marine Science and Engineering, Vol. 7, No. 12, pp. 422, 2019.‏
22. Tec-science, “Velocity distribution along a flow around a cylinder (flow separation)”; https://www.tec-science.com/mechanics/gases-and-liquids/flow-separation-boundary-layer-separation/.