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Forum Index : Windmills : LENZ2 DESIGN - EFFICIENCY

Author Message
Nacho
Newbie

Joined: 12/01/2019
Location: Spain
Posts: 4
 Posted: 04:34pm 12 Jan 2019 Copy link to clipboard Print this post

Hello,

I want to build a 2x600 W coaxial Lenz2 turbine.

- According to the Betz theory, maximum power can be extracted from any kind of wind turbine is 59.29 %.
- We can take out Lenz2 VAWT efficiency as in between 30% as of Savonius VAWT and 40% as efficiency of darrieus type VAWT, so efficiency estimated is 35%.

Should I consider that efficiency designing the Lenz2 turbine or that ineficiency is included in Ed Lenz size calculations?
Should I design a 40,71% plus 75% more powerfull vawt to reach desired goal power?

Thanks,
Nacho

yahoo2

Guru

Joined: 05/04/2011
Location: Australia
Posts: 1166
 Posted: 12:24pm 14 Jan 2019 Copy link to clipboard Print this post

Hi Nacho,

the elephant in the room is always the same.

How much energy does the wind at my chosen SITE and HEIGHT yield? Most turbines lose efficiency because of air turbulence not design problems. On a windy day it can steal half of the energy, on a lighter wind the turbine will not load the generator.

Most towers are too low.

ground obstacles make turbulence
warm days and warm ground make turbulence

where I live smooth air starts at 6-9 meters in on cold days, cloudy days and at night and 18+ meters on warm sunny days.

6 m/s of smooth air will get your 35% efficiency

4 m/s of turbulent air will average 0%
I'm confused, no wait... maybe I'm not...

electrondady1
Senior Member

Joined: 12/02/2009
Location: Canada
Posts: 208
 Posted: 01:18pm 14 Jan 2019 Copy link to clipboard Print this post

Ed did a lot of research on his wind mill . i think you might me better of building two of them if one is not enough.
if you widen the mill then the rpm is going to be decreased and you cut in speed is going to be affected
if you double the height or use two sets of vanes stacked up it will double your torque . that means your alternator might not be able to slow your mill down in a gale

it may have been our host but one of the members here built a lenze two using one of those washing machine motor/alternators. apparently the cog from that alternator set up a noisy vibration in the aluminum vanes. ed used an 8 inch dual rotor axial flux alternator.
i was part of a forum ed had mentored a few years back . one member used a double stacked lenze two that was counter rotating. so the mag rotors spun one direction and the stator rotated in the opposite direction.

have fun anyways
Edited by electrondady1 2019-01-15

Nacho
Newbie

Joined: 12/01/2019
Location: Spain
Posts: 4
 Posted: 03:49pm 15 Jan 2019 Copy link to clipboard Print this post

Hello "yahoo2" and "electrondady1",
Thanks so much for your commnents, support and suggestions.
I will start with one Lenz2 with one F&P motor and measure eveything .. and learn...
Best,
Nacho

yahoo2

Guru

Joined: 05/04/2011
Location: Australia
Posts: 1166
 Posted: 05:36am 16 Jan 2019 Copy link to clipboard Print this post

I look back on all the skills I learned from building HAWT's.

casting alloys and epoxy
building taperlock and multi-v pulleys
working with nichrome wire
3 phase power and motor controllers
vacuum forming
aerodynamics
diy electronics and writing code
automation controls
battery management
playing with transformers
creative problem solving
thinking about practical benefit vs \$\$\$ or theoretical efficiency.

none of it was wasted time. I use that knowledge in projects every week. I am thinking about doing something cool with a toyota prius drive system at the moment, it would never have happened without the wind and PV experience.

I only wish cheap Chinese carbon-fibre was available when I started (and spray-can 2K clearcoat paint)

I'm confused, no wait... maybe I'm not...

sonny97301
Newbie

Joined: 10/08/2019
Location: United States
Posts: 8
 Posted: 02:10pm 14 Aug 2019 Copy link to clipboard Print this post

some late info.   the amount of energy that ANY wind turbine will produce is a Function of its  ROTOR  RADIUS/swept area.   poor performance Should be expected, where the rotor radius is  Smaller.   this is why the rotors of  utility  wt's  just KEEP GETTING  BIGGER.

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