Abstract

The purpose of this work was to control undesired structure and vibrations caused from vortex shedding by controlling the flow downstream of the cylinder. The porosities of the outer cylinder and the splitter plate used for this purpose are available. The other parameter was plate angle based on the flow direction as a reference. The parameter expressed as porosities, ß was chosen to have a %70 openness for the outer cylinder (ß = 0.7) and was kept constant throughout all experiments. On the other hand, two different porosities were used for the splitter plate. For the first plate, there was no hole on the plate which we call ß = 0 or solid plate. For the second plate, it has ß = 0.7 porosity. ß = 0.7 porosity was also the value chosen for the outer cylinder. The range of the splitter plate angle was selected within 60o? ? ?180o with an increment of 30o. The results were extracted using two different methods. The first was the dye visualization experiment and the second is the PIV (Particle Image Velocimetry) measurement. As a result, it was observed that independently from the outer cylinder effect, the plate porosity and plate angle are effective on the level of turbulence and the flow structure in the annular region.

References

[1]. Roshko, A., On the drag and shedding frequency of two-dimensional bluff bodies. Tech.1954, Note 3169. NACA, Washington.
[2]. Roshko, A., Experiments on the flow past a circular cylinder at very high Reynoldsnumber. Journal of Fluid Mechanics, 1961. 10(3): p. 345-356.
[3]. Price, P., Suppression of the fluid-induced vibration of circular cylinders. Journal of theEngineering Mechanics Division, 1956. 82(3): p. 1-22.
[4]. Every, M., R. King, and D. Weaver, Vortex-excited vibrations of cylinders and cablesand their suppression. Ocean Engineering, 1982. 9(2): p. 135-157.
[5]. Bruneau, C.-H. and I. Mortazavi, Control of vortex shedding around a pipe section usinga porous sheath. International Journal of Offshore and Polar Engineering, 2006. 16(02).
[6]. Prasad, A. and C.H. Williamson, The instability of the separated shear layer from a bluffbody. Physics of Fluids, 1996. 8(6): p. 1347-1349.
[7]. Ozkan, G.M., et al., Flow around a cylinder surrounded by a permeable cylinder inshallow water. Experiments in Fluids, 2012. 53(6): p. 1751-1763.
[8]. Bengi Gözmen , H.A., Beşir Şahin, Vortex control of cylinder wake by permeablecylinder. 2013.
[9]. Akilli, H., B. Sahin, and N. Filiz Tumen, Suppression of vortex shedding of circularcylinder in shallow water by a splitter plate. Flow Measurement and Instrumentation, 2005.16(4): p. 211-219.
[10]. Ozkan, G.M., E. Firat, and H. Akilli, Passive flow control in the near wake of a circularcylinder using attached permeable and inclined short plates. Ocean Engineering, 2017. 134: p.35-49.
[11]. Sheng, J., H. Meng, and R. Fox, A large eddy PIV method for turbulence dissipationrate estimation. Chemical engineering science, 2000. 55(20): p. 4423-4434.
[12]. Fouras, A. and J. Soria, Accuracy of out-of-plane vorticity measurements derived fromin-plane velocity field data. Experiments in fluids, 1998. 25(5-6): p. 409-430.
[13]. Adrian, R.J., Particle-imaging techniques for experimental fluid mechanics. Annualreview of fluid mechanics, 1991. 23(1): p. 261-304.
[14]. Keane, R.D. and R.J. Adrian. Optimization of particle image velocimeters. inICALEO'89: Optical Methods in Flow and Particle Diagnostics. 1990. International Society forOptics and Photonics.