Why Do Wind Power Turbines Have Fewer Blades Than Hydro Power Turbines?

[scorpio_wan1945]

hello,

there is a question bugging my head for quite some time..

why wind power plant has lesser turbine blades while the one in hydro power plant has more?...

is it due to the density of the fluid?

thanks

 

[Astronuc]

It is probably a function of density (water has a density about 833 times that of air), speed of the flow both of which affect momentum and energy transfer. Water turbines are much more rigid because of the shear forces associated with the rushing water.

I believe wind turbines are optimized on radius (length) of the blades. Adding one more blade would increase the mass by another 33%, perhaps without added advantage.

The wind turbines cut out at around 65 mph (~97 ft/s), and I believe water turbine may have higher flows.

 

[Homer Simpson]

That seemed like an interesting question to me. Here's something off the net:

http://www.windpower.org/en/tour/design/index.htm

http://www.windpower.org/en/tour/design/concepts.htm

 

[scorpio_wan1945]

thanks for the explanation... and the links proves very useful :)

 

[Astronuc]

Some examples of hydro turbines:

http://www.voithsiemens.com/vs_e_prfmc_pwrful_prdcts_turbines.htm

http://www.toshiba.co.jp/f-ene/hydro/english/products/equipment/turbine.htm

http://www.hitachi.us/Apps/hitachicom/content.jsp?page=powerequipment/TurnkeyPowerPlants/HydroPlants/index.html&level=2&section=powerequipment&parent=TurnkeyPowerPlants&nav=left&path=jsp/hitachi/forbus/powerequipmentsystems/&nId=iD

http://www.gepower.com/prod_serv/products/hydro/en/turbines/index.htm