Venturi effect
The Venturi effect describes how the velocity of the fluid increases (thus increasing the kinetic energy of the water) as the cross section of the container decreases, like in a funnel. In the case of tidal stream generators a duct or shroud (otherwise known as a diffuser) can be used to increase the amount of power available. A funnel shape is built around or near the turbine that causes the flow rate of the water to accelerate - sometimes dramatically. These can cause up to 4 or 5 times higher power output than a similar sized turbine without a shroud because it's harnessing the energy from a greater amount of water.[2]
Many different styles of tidal stream generators can harness the Venturi effect.
References
- ↑ Wikimedia Commons [Online], Available: https://upload.wikimedia.org/wikipedia/commons/5/54/Venturifixed2.PNG
- ↑ Wise Geek. (August 7, 2015). What is a Venturi tube? [Online], Available: http://www.wisegeek.com/what-is-a-venturi-tube.htm