Well, after 3 days and a total of an hour tunnel time all is confirmed. First a couple shots of the tunnel. First one has the turbine set up and ready to go. The second gives you an idea of how massive this thing is...
The tunnel is a closed loop which goes outside the building all the way around to the back side and re-enters the building. Everything is computer controlled... quite impressive.
We dialed it in to match the output of my tunnel and I found I was 1/2 mph off in my readings ( to the good I might add ;o) ).
There were several tests done using windspeed and pressure. Most of the calculating they did because, to be quite honest, I had no idea what they were doing. When they were calculating pressure before and after I was lost... The windspeeds were calculated from inches of water which they said is more accurate. And lastly the tests were performed by measuring ft/sec.
So here are the numbers for how well the Lenz2 converts wind energy to mechanical energy. Firstly a refresher of the unit that was being tested... it stands 2ft x 2ft ( 4 sq ft total area ). I haven't changed the wings to the new version but there are winglets added to this unit. I wanted to get data on the original wings before proceeding.
Here we go... I'm going to keep it in mph since it's common to all of us and easy to understand...
. 7.38 mph starts charging 2.25 watts
. 10.85 mph 41% 10.56 watts
. 13.53 mph 38.9% 19.46 watts
. 15.61 mph 30.5% 23.39 watts
. 18.88 mph 31.4% 42.7 watts
Overall average of 35.45%
The efficiency is based on total area of the turbine from total power in the wind. If you factor in the Betz theory then the efficiency of the total possible that is extractable then it would look like this...
. 10.85 mph 68.8%
. 13.53 mph 65.3%
. 15.61 mph 51.1%
. 18.88 mph 52.8%
or an overall average of 59.5% of total possible.
I shot the entire session on video tape but it will be awhile before I can cut some clips from it. I'm going to go over it several times before I start pulling parts out. I came up with several ideas to improve it during the whole experience. It's definately been a fun and challenging journey ! I see another 30-40% of un extracted energy... I doubt it'll ever match betz but I'll bet I can get a few more watts out of it !
As I suspected the efficiency starts dropping in higher winds so the next wing change will hold the efficiency longer before dropping off although I still want to maintain a high lift/ dirty design to help control it in higher winds. The data gathered from the roof mounted unit tells me it doesn't drop the efficiency fast enough which could be controlled by a more efficient alternator now that I know what it's capable of.
Lots of fun ! And the fun continues...