Vortex induced vibration

Vortex-induced separator, 22 62-63 Vortex-induced vibration, 11 756 Vortex meters, mass flowmeters, 20 681 Vortex patterns, 11 755 Vortex precession meters, 11 668 Vortex shedding, 11 756 Vortex shedding meters, 11 668-669 Vortices, superconductor, 23 824-825 Voyage charters, 25 327 VP Sandoflam 5085, 11 491 V-type inks, 14 326 Vulcanizable silicone rubber, 25 129 Vulcanizable silicones, properties and applications of, 22 594-595, 596-597 Vulcanizates EPDM, 10 713 EPM/EPDM, 10 715 ethylene-acrylic elastomer, 10 698,... 

In spite of these ongoing developments, today almost all riser design analyses are performed by empirical methods. Static analysis is generally based on steady current loads (uniform or shear) and provides the riser deflected shape, stresses at various points on the riser, top and bottom angles, and its structural mode shape under load. Dynamic analysis considers both the inline and transverse unsteady loads. In addition to the riser shapes and stresses, it provides the vortex induced vibration, and fatigue life of the riser. 

It should be noted that many of the issues can be dealt with an improved design or stmctural modifications. This is the case, for example, for flutter- and vortex-induced vibration suppressions on bridge deck, obtained by means of section modifications or aerodynamic countermeasures (e.g., deflectors, fairings, and flaps). Similarly, an appropriate designed cable cross section and surface can minimize cable vibration. 

Towers Vortex-induced vibrations Passive TMD (Tuned Mass Dampers)... 

Deck Vortex-induced vibrations Passive FVD (fluid viscous dampers)... 

Once a vessel has been designed statically, it is necessary to determine if the vessel is susceptible to wind-induced vibration. Historically, the rule of thumb was to do a dynamic wind check only if the vessel L/D ratio exceeded 15 and the POV was greater than 0.4 seconds. This criterion has proven to be unconservative for a number of applications. In addition, if the critical wind velocity, V,., is greater than 50 mph, then no further investigation is required. Wind speeds in excess of 50 mph always contain gusts that will disrupt uniform vortex shedding. 

The flow of the coolant around components and structures can cause structural vibrations due to the unsteady characteristics of the gas motion. The turbulence and the vortex shedding from an object protruding into the flow are the main sources of flow-induced vibrations that are considered. Flow-induced vibration analysis is done in two steps 1) determination of... 

Tower-like structures are understood, in general, to be slender, tall structures (as television towers, lookout towers, chimneys, masts, and bridge pylons). Usually, gust-induced vibrations in the wind direction predominate, especially those at the fundamental bending frequency. The vibrations connected with vortex shedding that is transverse to the wind direction, however, can be more important. Particularly sensitive in this respect are steel chimneys (of welded construction, not insulated or lined with masonry, and with a fixed base). Vibrations of chimneys, masts and other low-damped tower-like structures lead to structural safety (fatigue) and serviceability problems. The occurrence... 

J. Chaplin, Vortex- and wake-induced vibrations of deep water risers, Fourth Int. Conf. Fluid Structure Interaction, Ashurst, Southampton, UK (2007). 

This section concerns the static problem of guy wires. Experience has shown that if guy cables are properly tensioned, flow-induced vibration (FIV), induced by vortex shedding, is of minimal concern. The reason is that the natural frequency of the stack is well above the resonant range. One reason for pre-tensioning the cables is to avoid FTV. 

The vibration induced by the fluid flowing over the tube bundle is caused principally by vortex shedding and turbulent buffeting. As fluid flows over a tube vortices are shed from the down-stream side which cause disturbances in the flow pattern and pressure distribution round the tube. Turbulent buffeting of tubes occurs at high flow-rates due to the intense turbulence at high Reynolds numbers. 

Tube vibrations in a tube bundle are caused by oscillatory phenomena induced by fluid (gas or liquid) flow. The dominant mechanism involved in tube vibrations is the fluidelastic instability or fluidelastic whirling when the structure elements (i.e., tubes) are shifted elastically from their equilibrium positions due to the interaction with the fluid flow. The less dominant mechanisms are vortex shedding and turbulent buffeting. 

Vibration-induced fluidizing is accompanied, as in the vortex method, by the separation of the powder material by particle size and mass. Therefore, application of inhibited layers of the coating can be regulated using only one fluidizing bath incorporating a pol3mier powder mixture with Cl. With this aim, vibrations of different frequencies are imposed in turn on the powder and article in a bath separated into sections by, e.g., baffles. 

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