Measurements of fluctuating air loads on a circular cylinder (Unsteady lift and drag forces on circular cylinder in normal airflow, determining spatial variations of random loads)

1964 ◽  
Author(s):  
L.V. SCHMIDT
Keyword(s):  
Circular Cylinder ◽  
Spatial Variations ◽  
Drag Forces ◽  
Random Loads ◽  
Lift And Drag ◽  
Unsteady Lift

Lift And Drag Forces On A Submerged Circular Cylinder

1971 ◽  
Author(s):  
J.F. Beattie ◽  
L.P. Brown ◽  
B.F. Webb
Keyword(s):  
Circular Cylinder ◽  
Drag Forces ◽  
Lift And Drag

Model Test Study on Vortex-Induced Motions of a Floating Cylinder

2009 ◽  
Author(s):  
Ying Wang ◽  
Jianmin Yang ◽  
Tao Peng ◽  
Xin Li
Keyword(s):  
Circular Cylinder ◽  
Scale Model ◽  
Visualization System ◽  
Forced Motion ◽  
Drag Forces ◽  
Fluid Field ◽  
Helical Strakes ◽  
Induced Motion ◽  
Motion Characteristics ◽  
Lift And Drag

Vortex-Induced Motions (VIM) under current flow is an important issue for surface piercing cylinders, such as Spar platforms and floating buoys, since it affects the motion performance of these structures greatly. In recent years this phenomenon attracts much attention and many researchers have been making efforts to deal with this problem. VIM is such a complicated phenomenon that more fundamental studies are needed to understand the essence behind VIM. This paper mainly concentrates on a circular cylinder, aiming to eliminate outside influences and reveal the inherent characteristic of vortex-induced motion mechanism. A circular cylinder with an aspect ratio of 1:2.4, which could be considered as a scale model for the hard tank of a typical Truss Spar, is studied by experimental method to investigate the surrounding fluid field, the excitation forces and Vortex-Induced Motion characteristics under various governing parameters, such as the current velocity and direction, the mooring stiffness and distribution, the use and efficiency of helical strakes, and so on. By using a simple flow visualization system, the unsteady flow passing the circular cylinder and the vortices in the wake are captured and recorded. The cylinder is tested respectively under fixed, forced-motion and elastically moored conditions. The fluid field, the vortex structures, and the lift and drag forces under fixed and forced-motion conditions are measured, the VIM performance of the cylinder with two different mooring distributions are studied, and strake efficiency is studied considering current directionality and strake height influence.

Turbulent fluid-structure interaction of water-entry/exit of a rotating circular cylinder using SPH method

2015 ◽  
Vol 26 (08) ◽  
pp. 1550088 ◽  
Author(s):  
Jafar Ghazanfarian ◽  
Roozbeh Saghatchi ◽  
Mofid Gorji-Bandpy
Keyword(s):  
Circular Cylinder ◽  
Water Entry ◽  
Numerical Code ◽  
Navier Stokes ◽  
Inertia Force ◽  
Entry And Exit ◽  
Sph Method ◽  
Drag Forces ◽  
Rotating Circular Cylinder ◽  
Lift And Drag

This paper studies the two-dimensional (2D) water-entry and exit of a rotating circular cylinder using the Sub-Particle Scale (SPS) turbulence model of a Lagrangian particle-based Smoothed-Particle Hydrodynamics (SPH) method. The full Navier–Stokes (NS) equations along with the continuity have been solved as the governing equations of the problem. The accuracy of the numerical code is verified using the case of water-entry and exit of a nonrotating circular cylinder. The numerical simulations of water-entry and exit of the rotating circular cylinder are performed at Froude numbers of 2, 5, 8, and specific gravities of 0.25, 0.5, 0.75, 1, 1.75, rotating at the dimensionless rates of 0, 0.25, 0.5, 0.75. The effect of governing parameters and vortex shedding behind the cylinder on the trajectory curves, velocity components in the flow field, and the deformation of free surface for both cases have been investigated in detail. It is seen that the rotation has a great effect on the curvature of the trajectory path and velocity components in water-entry and exit cases due to the interaction of imposed lift and drag forces with the inertia force.

The lift and drag forces on a circular cylinder in a flowing fluid

1964 ◽  
Vol 277 (1368) ◽  
pp. 32-50 ◽  
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Drag Force ◽  
Central Axis ◽  
Flowing Fluid ◽  
Drag Forces ◽  
Lift And Drag

Apparatus is described for measuring directly fluctuating lift and drag forces and steady mean drag force. These forces are exerted upon a cylinder placed so that its central axis is perpendicular to the direction of flow of water in a channel. Results are given for the stationary cylinder for the range of Reynolds number 3600 to 11 000.

Some effects of intense turbulence on the aerodynamics of a circular cylinder at subcritical Reynolds number

1972 ◽  
Vol 52 (3) ◽  
pp. 543-563 ◽  
Author(s):  
David Surry
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Vortex Shedding ◽  
Large Scale ◽  
Central Element ◽  
Structural Response ◽  
Describing Function ◽  
Free Stream Turbulence ◽  
Drag Forces ◽  
Unsteady Lift

The effect, of high intensity large-scale free-stream turbulence on the flow past a rigid circular cylinder has been studied experimentally a t subcritical Reynolds numbers. Grids were used to produce homogeneous turbulence fields with longitudinal scales ranging from 0·36 to 4·40 cylinder diameters and with longitudinal intensities greater than 10%. Power and cross-spectra of the turbulence components (the ‘system input’) have been measured in order to carefully define the turbulence characteristics.In the response experiments, a special model measured arbitrary two-point pressure correlations. Subsequent integrations yielded the specbral properties of the unsteady lift and drag. Measurements of mean drag and Strouhal frequency indicate that to some extent even severe large-scale turbulence can be considered to be qualitatively equivalent to an increase in the effective Reynolds number. Vortex shedding is not seriously disrupted by severe turbulence, but is affected more by low than by high frequencies. The unsteady lift response is still dominated by the vortex shedding, whereas the unsteady drag becomes primarily a response to turbulence. The cross-spectra of the drag forces for the one turbulence case examined overlay well when plotted against lateral separation divided by wavelength. This has enabled a ‘describing function’ for the drag response to turbulence to be derived. This describing function is the central element needed for the calculation of the structural response of such cylinders in the drag direction.

On the Suppression of Vortex Shedding From Circular Cylinders Using Detached Short Splitter-Plates

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Behzad Ghadiri Dehkordi ◽  
Hamed Houri Jafari
Keyword(s):  
Circular Cylinder ◽  
Vortex Shedding ◽  
Splitter Plate ◽  
Circular Cylinders ◽  
Staggered Grid ◽  
Drag Forces ◽  
Splitter Plates ◽  
Parallel Arrangement ◽  
Lift And Drag ◽  
Good Agreement

Flow over a circular cylinder with detached short splitter-plates is numerically simulated in order to assess the suppression of periodic vortex shedding. A finite-volume solver based on the Cartesian-staggered grid is implemented, and the ghost-cell method in conjunction with Great-Source-Term technique is employed in order to enforce directly the no-slip condition on the cylinder boundary. The accuracy of the solver is validated by simulation of the flow around a single circular cylinder. The results are in good agreement with the experimental data reported in the literature. Finally, the flows over a circular cylinder with splitter-plate in its downstream (off and on the centerline) are computed in Re=40 as a nonvortex shedding case and in Re=100 and 150 as cases with vortex shedding effects. The same simulations are also performed for the case where dual splitter-plates are in a parallel arrangement embedded in the downstream of the cylinder. The optimum location of the splitter-plate to achieve maximum reduction in the lift and drag forces is determined.

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