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VIV and galloping of single circular cylinder with surface roughness at 3.0×10 4≤Re≤1.2×10 5

Publication Type : Journal Article

Publisher : Ocean Engineering

Source : Ocean Engineering, Volume 38, Number 16, p.1713-1732 (2011)

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Keywords : boundary layer, Circular cylinders, cylinder, Damping, flow control, Flow-induced motion, Fluid structure interaction, Galloping, Hydrokinetic energy, kinetic energy, oceanic current, Passive Turbulence Control, Platinum compounds, Renewable resource, Reynolds number, Shear flow, Surface properties, Surface roughness, turbulence, vibration, Vibrations (mechanical), Visualization, VIV, VIVACE Converter, vortex flow, Vortex induced vibration

Campus : Amritapuri

School : School of Engineering

Department : Mechanical Engineering

Year : 2011

Abstract : Passive Turbulence Control (PTC) in the form of selectively distributed surface roughness is used to alter Flow Induced Motion (FIM) of a circular cylinder in a steady flow. The objective is to enhance FIMs synchronization range and amplitude, thus maximizing conversion of hydrokinetic energy into mechanical energy by oscillator in vortex-induced vibration and/or galloping. Through additional viscous damping, mechanical energy is converted to electrical harnessing clean and renewable energy from ocean/river currents. High Reynolds numbers (Re) are required to reach the high-lift TrSL3 (Transition-Shear-Layer- 3) flow regime. PTC trips flow separation and energizes the boundary layer, thus inducing higher vorticity and consequently lift. Roughness location, surface coverage, and size are studied using systematic model tests with broad-field laser visualization at 3.0×10 4lt;Relt;1.2×10 5 in the low-turbulence free-surface water-channel of the Marine Renewable Energy Laboratory of the University of Michigan. Test results show that 16° roughness coverage is effective in the range (10°80°) inducing reduced vortex-induced vibration (VIV), enhanced VIV, or galloping. Range of synchronization may increase or decrease, galloping amplitude of oscillation reaches three diameters; wake structures change dramatically reaching up to ten vortices per cycle. Conversion of hydrokinetic energy to mechanical is enhanced strongly with proper PTC. © 2011 Elsevier Ltd.

Cite this Research Publication : C. - Ca Chang, Kumar, Rab Ajith, and Bernitsas, M. Mac, “VIV and galloping of single circular cylinder with surface roughness at 3.0×10 4≤Re≤1.2×10 5”, Ocean Engineering, vol. 38, pp. 1713-1732, 2011.

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