Effect of Cylinder Gap Ratio on The Wake of a Circular Cylinder Enclosed by Various Perforated Shrouds

Nurul Azihan  Ramli; Azlin Mohd Azmi; Ahmad Hussein  Abdul Hamid; Zainal Abidin  Kamarul Baharin; Tongming  Zhou

doi:10.37934/cfdl.13.4.5168

Authors

Nurul Azihan Ramli School of Mechanical Engineering, College of Engineering, Universiti Teknologi Malaysia, 40450 Shah Alam, Selangor, Malaysia
Azlin Mohd Azmi Solar Research Institute (SRI), Universiti Teknologi MARA, 40450 Shah Alam, Selangor, Malaysia
Ahmad Hussein Abdul Hamid School of Mechanical Engineering, College of Engineering, Universiti Teknologi Malaysia, 40450 Shah Alam, Selangor, Malaysia
Zainal Abidin Kamarul Baharin School of Mechanical Engineering, College of Engineering, Universiti Teknologi Malaysia, 40450 Shah Alam, Selangor, Malaysia
Tongming Zhou Department of Civil, Environmental and Mining Engineering, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia

DOI:

https://doi.org/10.37934/cfdl.13.4.5168

Keywords:

Perforated shroud, vortex shedding, passive control

Abstract

Flow over bluff bodies produces vortex shedding in their wake regions, leading to structural failure from the flow-induced forces. In this study, a passive flow control method was explored to suppress the vortex shedding from a circular cylinder that causes many problems in engineering applications. Perforated shrouds were used to control the vortex shedding of a circular cylinder at Reynolds number, Re = 200. The shrouds were of non-uniform and uniform holes with 67% porosity. The spacing gap ratio between the shroud and the cylinder was set at 1.2, 1.5, 2, and 2.2. The analysis was conducted using ANSYS Fluent using a viscous laminar model. The outcomes of the simulation of the base case were validated with existing studies. The drag coefficient, Cd, lift coefficient, Cl and the Strouhal number, St, as well as vorticity contours, velocity contours, and pressure contours were examined. Vortex shedding behind the shrouded cylinders was observed to be suppressed and delayed farther downstream with increasing gap ratio. The effect was significant for spacing ratio greater than 2.0. The effect of hole types: uniform and non-uniform holes, was also effective at these spacing ratios for the chosen Reynolds number of 200. Specifically, a spacing ratio of 1.2 enhanced further the vortex intensity and should be avoided.

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