Performance improvements

[KBwind]

Hola from Nicaragua,
I have returned here following the holidays to continue my research and work with small scale VAWTs for developing countries. In early Dec I finished a prototype turbine that I would like to use for rural electrification projects throughout the country as many many communities have zero access to electricity and it stiffles efforts to improve economic and living conditions. A big thanks to the commentors on my previous posts who have helped me along the way. I was very happy upon my return to find the turbine has been operating without any issue charging the battery bank in the house through a considerable transmission run of 300 ft with 14 AWG wire (I rectify at the house). The last few weeks I have been looking into power output and what I can do in the future to get more power. Currently I´ve had a max output of 16 watts and on an average day it will charge at about 4-7 watts for about 8 hours. Now this power is rather modest but when living miles and miles away from the nearest utility pole everything helps (we´re currently the only place in the village with electricity and we must charge about 5 cell phones and 3 flashlights daily for locals in the area. Also I´m rather proud that I build the turbine without machining or welding.
Alright so from testing rpm vs. windspeed with the fully loaded prop I have a found that the turbine runs at a seemingly constant TSR of 0.8. I´ve yet to see consistant wind above 7 m/s so I´m not sure if the TSR will increase above this level but here´s hoping. By calculating my potential power output (at a given windspeed) for my given swept area using the standard equation I find that output will depend on the turbine power coefficient and the electrical efficiency of the alternator. From literature I´ve found that a savonious rotor will run at a CP of 0.3 at a TSR of 0.75. I´m hoping that I can be somewhere in this range as I´m operating at a higher TSR than the S rotor. I do know that there is a workable range of 30-150 rpm in the wind wonditions the area experiences.When I calculate power for my swept area at this CP I find I should be making about 10 watts at 4 m/s before electrical and mechanical losses. Well I´m way off of that target even considering an electrical efficiency of 0.5 and so I´m left to ponder how I can improve the system. Right now I have a per phase resistance of 2 ohms with the 280 turns of 18 awg. Is this a reasonable value, am I losing too much power to resistive loss? I´ve also been thinking of trying a 6 pole alt to get more magenetic material in the alternator and lower the cut in speed. Will a 6 pole alt completely overpower the prop and result in it stalling badly since the absolute max power this turbine could ever produce before the alt is about 250 watts?

Any input/discussion would bbe greatly appreciated. I apologize for the sloppiness of this post as I¨am in a bad internet call center right now and my time is up in one minute. I will be around the next three days to check any comments and respond with more info.
Adios

[XXLRay]

Although your internet connection might be quite bad some pictures or sketches could clearify waht kinf of turbine you set up. It would be much easier to give hints on improvements if we knew what you have built (as I understood your post it is NOT a Savonius).

[SparWeb]

Using the turbine you already have, performance an usually be improved by raising it higher.  How far from the ground is it now?  What obstacles are nearby?
Please believe me that VAWT's have NO special immunity from turbulence, despite what 99% of the world will tell you.  Keeping it away from buildings, trees, and the ground will increase the energy you collect.  Sometimes the height of the tower or building is limited, so this answer doesn't fit all cases. 
Sorry there isn't enough information to check calculations - that would be difficult in any case.  Usually it is hard to measure wind speed accurately without special equipment.  I would avoid trusting calculations if your uncertainty of wind speed is +/- 1 m/sec.

[hayfarmer]

Hola kbwind,attached is a link to a non profit org that helps 3rd world countries with solar power,I see they are working in Brazil and thought you may shoot them an email to see if they can add solar to your system.I forwarded the link to  to this thread to them in hope they can help you and your village as well.good luck .

http://www.self.org/contact1.shtml

also a grant source for 3rd world R.E. projects is


http://www.climatefundsupdate.org/listing/scaling-up-renewable-energy-program



hayfarmer

[KBwind]

Thanks for the responses....I basically put the OP up and then had to disappear back to the coast unexpectedly. I've spent more time observing the turbine and believe I understand the limitations to its power output. Using the tower I have at the moment (three tree trunks in a cement foundation) the tallest part of the turbine is at about 16 ft- puny by HAWT standards. Sparweb you are correct in suggesting the best way for more power is a larger tower. With winds up to 10 m/s at ground level I can only imagine what they would be another 15 ft higher. Turbulence is an issue at the moment as there are significant obstacles in the vicinity of the turbine such as the house is 300 ft away and 10 ft brush along the coast line. I can't do anything about the brush because it offers a bit of protection for the house from the ocean in the event of an unusually high tide (we sleep about 80 meters from high tide - I want all the protection I can get). Anyways I've been designing a second turbine to build and install in the next two weeks and I will be using a tilt-up style with some modifications to suit the vertical axis configuration. Hopefully I can get the hub height to 25 ft and I'll be putting it further away from the house. Also its time to use a 6 pole design - with the current cut in of 73 RPM the turbine will only spin 25-30 RPM beyond the cut in for an average wind day. This is clearly my limiting factor. A 6 pole will increase the pole passing frequency by 33%. Alright....enough for now...tsunami alert for Nicaragua and I need to inform the village. Wish me Godspeed in alerting them. Adios
KB