Computational and Experimental Assessment of Turbulence Stimulation on Flow Induced Motion of a Circular Cylinder

Abstract

Vortex-induced vibrations (VIVs) are highly nonlinear and it is hard to approach the problem analytically or computationally. Experimental investigation is therefore essential to address the problem and reveal some physical aspects of VIV. Although computational fluid dynamics (CFDs) offers powerful methods to generate solutions, it cannot replace experiments as yet. When used as a supplement to experiments, however, CFD can be an invaluable tool to explore some underlying issues associated with such complicated flows that could otherwise be impossible or very expensive to visualize or measure experimentally. In this paper, VIVs and galloping of a cylinder with selectively distributed surface roughness—termed passive turbulence control (PTC)—are investigated experimentally and computationally. The computational approach is first validated with benchmark experiments on smooth cylinders available in the literature. Then, experiments conducted in the Marine Renewable Energy Laboratory (MRELab) of the University of Michigan are replicated computationally to visualize the flow and understand the effects of thickness and width of roughness strips placed selectively on the cylinder. The major outcomes of this work are: (a) Thicker PTC initiates earlier galloping but wider PTC does not have a major impact on the response of the cylinder and (b) The amplitude response is restricted in VIV due to the dead fluid zone attached to the cylinder, which is not observed in galloping.

Akiş Kaynakli Ti̇treşi̇mde İki̇ Ardişik Si̇li̇ndi̇rden Elde Edi̇len Gücün Parametri̇k Olarak İncelenmesi̇

“…Two PTC circular cylinders of diameter D = 0.0889m and length L = 0.914m was utilized for this experiments. An evaluation of blockage effects was studied by Kinaci et al (2016) shown in Figure . 3, the test cylinders were mounted on two linear end springs and the cylinder motion was allowed in the cross-flow direction only. In this study, center to center distance between two cylinders is between 1.57D and 2.57D.…”

“…Elastic bodies with circular cross section in a flow usually experience VIV, while galloping occurs on a body with non-circular cross section (Blevins, 1990). Depending on the flow speed, the geometry of the body and the oscillator parameters, these two FIVs may coexist in a transition part between them, may overlap, or may be separated (Bernitsas at al., 2007, Chang, 2011, Kinaci et al, 2016, Park et al, 2013a.…”

Effects of installation position of fin-shaped rods on wind-induced vibration and energy harvesting of aeroelastic energy converter

“…The minimum working flow velocity in water can be as low as 0.25 m s −1 . In order to further improve the energy conversion efficiency of VIVACE, the VIVACE group carried out a series of research on the factors affecting flow-induced vibration, including the surface roughness of cylinder [33,34], the cross section shape of cylinder [35], and the number of cylinders [36][37][38], system damping and stiffness [39], etc. VIVACE converter realizes the harvesting of low-speed hydrokinetic energy using electromagnetic technology.…”