The Tacoma narrows bridge incident<br />Vortex induced vibration<br />How a fish propels itself in water<br />The VIVACE<br />How the vivace works<br />Why vivace<br />High utilization expected for vivace<br />Salient features of vivace<br />Advantages <br />References<br />
The tacomanarrows bridge incident (1940)November 7, 1940, at 11:00 am (Pacific time)<br />
(VIV) are motions induced on bodies facing an external flow by periodical irregularities on this flow. <br />They are experienced by any unstable cylindrical objects which may be small car antennas or 120 foot diameter platforms used in off-shore engineering<br />
Vortex Induced Vibrations (VIV) results from vortices forming and shedding on the downstream side of a bluff body in a current.<br />If the frequency of vortex shedding matches the resonance frequency of the structure, the structure will begin to resonate and the structure's movement can become self-sustaining.<br />
VIV OF A CYLINDER IN FLUID FLOW<br />Real fluids always present some viscosity.<br />Boundary layer will form and thus the flow around the cylinder will be slowed down while in contact with its surface.<br />At some point this boundary layers separate from the body due to its excessive curvature. <br />Vortices are then formed changing the pressure distribution along the surface. <br />When the vortices are not formed symmetrically around the body, different lift forces develop on either side of the body, thus leading to motion transverse to the flow. <br />
CONSTRUCTION<br />Entails a cylinder that hangs horizontally across the flow of water. <br />The cylinders are free to move through the guide ways in the vertical direction<br />The cylinder holds a magnet at the end, inside the guide ways.<br />A metal coil winding is provided inside the guide ways<br />
THE CONVENTIONAL WIND TURBINE`<br />The flow of air across the blades creates lift that turns the rotor of a wind turbine.<br />The world’s largest wind farm, the Horse Hollow Wind Energy Center in Texas, generates 735.5 MW at peak power with 291 1.5 MW wind turbines and 130 2.3 MW wind turbines spread over an area of 190 square kilometers. <br />The rated wind speed required for this output is 12m/s<br />The farm occupies a volume of almost 22 cubic kilometers.<br />
WHY THE VIVACE?<br /><ul><li>Water has a high energy density and is 830 times denser than air.
The comparable water flow velocity to air velocity of 12m/s is 1.3 m/second.
The Corresponding power density is 185 watts per cubic meter.
The power density of the VIVACE converter is 14,600 times greater than that of the wind farm.
Power is generated at a cost of </li></ul>2.45 RS/KWH<br />
SALIENT FEATURES<br />CLEAN ENERGY<br />DOESN’T DISRUPT THE NATURAL FLORA & FAUNA<br />NO DAMS OR TURBINES ARE USED<br />POWER AT 2.75 RS/KWh<br />CONSISTANT AND RELIABLE POWER GENERATION THROUGHT THE YEAR.<br />GENERATES POWER IN WATER CURRENTS<br /> OF EVEN 1 KNOTS <br /> (I KNOT=1.85Km/hr)<br />
ADVANTAGES<br /><ul><li>Has high energy density
Have a design life of at least 15-20 years </li></li></ul><li>REFERENCES<br />ASME JOURNAL (mechanical engineering) - APRIL 2010<br />www.vortexhydroenergy.com<br />www.asme.org/vivaceconverter<br />www.rexresearch.com/bernitsas/bernitsas.htm<br />www.techtransfer.umich.edu<br />www.renewableenergyworld.com<br />memagazine.asme.org/Articles/2010/April/Out_Vortex.cfm<br />
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