Open River hydro - airfoil design?

[riverpower]

Hi everyone,  

   I've learned alot from reading the answers to other 'open river' questions.  I have a tidal river with flows up to 1.5 m/sec (zero head).  I think I will look into trying an electric trolling motor and putting a larger fan blade on it to see what it does.  Maybe it will generate something.  I'm not sure whether ducting (large area down to the smaller fan blade area) would help this or not. (there seems to be serious disagreement over whether ducting helps or not, in an open river environment).

But my main question is:  I still think a vertical axis turbine would work better (darrieus or savonius design).  I've contacted everyone I can find who claims to have these, and they are quite expensive (payback would be measured in decades, just for the turbine alone), so I'd like to try to build my own airfoils for an underwater vertical axis turbine.  Is this crazy?  Does anyone have any design information for these, or places I should go look for this?  I'd rather start from a known design than start from scratch.  Any help or pointers would be greatly appreciated.

Thanks,

Dave Hempstead

[Countryboy]

I believe you may want to research a Gorlov turbine.

[riverpower]

Hi,

   I looked into the Gorlov.  In fact Professor Gorlov worked for Northeastern U, here in Massachusetts.  Apparently he sold the rights to his turbine to a company in Texas.  I think the company is GCK.  I have contacted them, and they are looking into commercial applications (large turbines and arrays of turbines), not micro-hydro setups.  I think I got a price from them, but it was very high for my river flow.  

   Do you know where I could get the design specs for a gorlov, so I could try to fabricate one myself???   THey are supposed to be more efficient, so I'd like to give it a shot, if I could learn what shape the blades need to be.

Thanks

[thefinis]

For an open flow river setup unless you are able to place something in the best flow area like the middle of the river it would seem to me that an old fashion paddle wheel would work and be easy to build. It gives you a lot of area and no upstream drag to fight which is one problem you will face with a submerged vertical design. It can be made to float with changing tides and will work fine in either direction as flow reverses if that is what you mean by tidal river. Sometimes I feel that we overlook the old ways because we are looking so hard at the new ways. You have a slow flow you can count on and it sounds like a large area to extract from(open river) so use a large area turbine for energy capture of whatever design.

I am no expert but if you restrict flow at the bank like with a plywood v or a rock levee/jetty doesn't the flow increase near the outer point as it goes around the edge of the restriction trying to take the shortest path into the area downstream behind it? Any ducting if designed right should help but in an open flow river setting the rewards are reduced as it wants to just flow around a restriction.

Finis

who wishes he had a river

[vawtman]

I wonder how that flapper turbine that Finis posted last week would work if the water is fairly clean.

  Have fun Dave

[DBuller]

Hey Dave,

   My design can be made with cheap PVC and create the power with an off the shelf Pelton system. If you have questions how it works, drop me an email.

-Dennis

http://www.WildWaterPower.com

WildWaterPower@msn.com

[The Crazy Noob]

If you know the patent number you can look it up at http://www.freepatentsonline.com (you can get it in PDF-format) or just search their database for the turbine. You are allowed to built a copy of the turbine for yourself if you don't plan on selling the turbines.

[riverpower]

Hi Dennis,

   Interesting webpage.  I would be very interesting to hear about any quantification you get.  I see one of the turbines generates 6 watts.  

Dave

[riverpower]

Hi,

   I will go find the patent number for the Gorlov, and see if it is buildable without an extreme number of custom tools.  Thanks for the link.

Dave

[riverpower]

Thanks to Nando for sending me a number of papers written on river power.  While none of them are directly applicable, some may lead me to a possible answer.  If/when I find one that I can try, I'll post my results.

Dave

[badmoonryzn]

I too am working on a way to use the flow going by my house. I have a river running in a rapid running at 3 mph. I have decided on an undershot wheel. I will use a lifting device like the old Salem witch dunking machine from the 1700's so I can pull the machine out of the water if needed and it will be counterbalanced so it will not weigh more than 50 pounds in the water. It will float on two pontoons shaped like a catamaran. I want to make sure it is light enough to come out of the water in case debris comes down the river. The river goes up and down depending on the weather and the realise of water from the dam upstream. I'm shooting for a 5kw first and then a 10kw. We will see. Good luck with yours.

Badmoon

[yellowcat]

you may want to look at NGC marine electric motors. they can be used as propulsion or regenerative. So if you can find out the way they are built you can possibly make them. On the St-Laurence river (2 miles wide) we have tidal currents downstream 3 to 4 knts, upstream 2 knots. If you have a good anchor system, your raft generator will turn itself depending on the tide direction. Deflectors will accelerate the current, the loads are surprising. If your deflector is snuged against the bottom and going up like a beach, you shouldl have a better result. We see this at the occasionnal old ferry docks, if we swim at the end of the dock, 2 things happen. 1 - a faster current down stream, 2 - a suction back upstream current swirl, you could i suppose use both for more efficiency. The suction is so powerfull it can drag a kid underwater, especially at the 5 knots areas. Do you have environmental issues in your area ? Check it out before you do anything in the river. Here in Canada, you need a permit to look at the water ...

Water is 800 times more powerfull than air i am told. Most likely, the wheel would be your best bet, it is on the surface and algeas should not clog it, Then you can use the volvo break gen design, build a combo wind/water system ...

mike