EXPERIMENTAL INVESTIGATION OF FLOW STRUCTURE DOWNSTREAM OF PERMEABLE CYLINDERS

Yıl 2018, Cilt: 2 Sayı: 2, 54 - 59, 15.05.2018

Bengi Şanlı Hüseyin Akıllı

https://doi.org/10.31127/tuje.349532

Öz

Flow
structure downstream of permeable cylinders was investigated using high-image
density Particle Image Velocimetry technique in deep water. The free stream
velocity is U_∞= 156 mm/s, which corresponds to the Reynolds number
of Re=6250 based on the cylinder diameter D=37.5 mm. To reveal the effect of
the porosity, four different porosities (β= 0.4, 0.5, 0.6 and 0.7) were used.
This study showed that the usage of permeable cylinder decreases the occurrence
of large-scale vortical structures downstream of the bluff body. As the
porosity increases, turbulent kinetic energy, Reynolds shear stress and
intensity of turbulences decrease as a sign of attenuated fluctuations in the
wake region. For the permeable cylinders having the porosity higher than 0.6,
the flow behaves as there is no object in flow. 

Anahtar Kelimeler

PIV, vortex shedding, permeable cylinder, Deep Water

Kaynakça

• Akansu, Y. E. and Fırat, E. (2010). “Control of flow around a square prism by slot jet injection from the rear surface.” Experimental Thermal and Fluid Science, Vol.34 No.7, pp. 906-914.
• Al-hajerı, M. H., Aroussi, A. and Witry, A. (2009) Numerical Simulation of Flow Past Multiple Porous Cylinders. Journal of fluids engineering-transactions of the asme, Vol.131, No.7, 071101.
• Corke, T. C., Enloe, C. L. and Wilkinson, S. P. (2010) Dielectric barrier discharge plasma actuators for flow control. Annual Review of Fluid Mechanics, Vol.42, pp. 505-529.
• Ekmekci A and Rockwell D. Effects of a geometrical surface disturbance on flow past a circular cylinder: a large-scale spanwise wire. Journal of Fluid Mechanics, 2010; 665: 120-157.
• Farhadi M, Sedighi K, Fattahi E. Effect of a splitter plate on flow over a semi-circular cylinder. Proc. IMechE Part G: J. Aerospace Engineering, 2010; 224: 321-330.
• Feng L-H and Wang J J. Synthetic jet control of separation in the flow over a circular cylinder. Experiments in Fluids, 2012; 53: 467–480.
• Fujısawa N, Takeda G. Flow Control Around a Circular Cylinder by Internal Acoustic Excitation. Journal of Fluids and Structures, 2003; 17: 903– 913.
• Gim O S, Kim S H and Lee G W. Flow control behind a circular cylinder by control rods in uniform stream. Ocean Engineering, 2011; 38(17-18): 2171–2184.
• Gozmen B, Akilli H and Sahin B. Passive control of circular cylinder wake in shallow flow. Measurement, 2013; 46: 1125-1136.
• Gozmen B and Akilli H. Flow control downstream of a circular cylinder by a permeable cylinder in deep water. Wind and Structures, 2014; 19(4): 389-404.
• Hiejima S, Kumao T and Taniguchi T. Feedback control of vortex shedding around a bluff body by velocity excitation. International Journal of Computational Fluid Dynamics, 2005; 19(1): 87-92.
• Li Z, Navon I M, Hussaini M Y and Le Dimet F-X. Optimal control of cylinder wakes via suction and blowing. Computers & Fluids, 2003; 32: 149–171.
• Lim H-C and Lee S-J. PIV Measurements of near wake behind a U-grooved cylinder. Journal of Fluids and Structures, 2003; 18 (1): 119-130.
• Muddada S and Patnaik B S V. An assessment of turbulence models for the prediction of flow past a circular cylinder with momentum injection. Journal of Wind Engineering and Industrial Aerodynamics, 2010; 98: 575-591.
• Nakamura H and Igarshi T. Omnidirectional reductions in drag and fluctuating forces for a circular cylinder by attaching rings. Journal of Wind Engineering and Industrial Aerodynamics, 2008; 96: 887–899.
• Ozkan G M, Oruc V, Akilli H and Sahin B. Flow around a cylinder surrounded by a permeable cylinder in shallow water. Experiments in Fluids, 2012; 53(6): 1751-1763.
• Pinar E, Ozkan G M, Durhasan T, Aksoy M M, Akilli H and Sahin B. Flow structure around perforated cylinders in shallow water. Journal of Fluids and Structures, 2015; 5: 52–63.
• Raffel M, Willert C E and Kompenhans J. Particle Image Velocimetry a Practical Guide, 1998, Springer, Göttingen.
• Sahın B, Ward-Smıth A J. The use of perforated plates to control the flow emerging from a wide-angle diffuser. Heat and Fluid Flow, 1987; 8 2: 124-131.
• Sudhakar Y and Vengadesan S. Vortex shedding characteristics of a circular cylinder with an oscillating wake splitter plate. Computers & Fluids, 2012; 53: 40–52.