Under water VAWT or would it be VAHT?

[12AX7]

Dear Diary..

I wonder if this would be better placed in the Hydro section, Wind,  or maybe the Pub.
This would be installed in a river.
Been kicking the idea of a Hydro VAWT,  but haven't a clue where to start in the blade profile. 

The location would take a turbine about 40 in (maybe 50in) diameter and it's height is still open to debate.
Currently I'm thinking that the blades would be tall enough to take advantage of the river at it's "normal" max height/depth (about five feet).   The river flow "I'm guessing" is about 8mph.

I know that this doesn't sound like much (if I was talking about air) but anyone standing in water current moving at 6mph and five feet deep would appreciate just how much energy is there (not to mention a 40x60in cross sectional area).
Now, maybe 40% of it's operational time (I'll have to yank it out in the winter months) the water level will moderate, and drop to a depth of about three feet (now a cross sectional area of 40x36in.) and the flow would slow down to about 6mph (still a lot of energy)

Blade profiles are over my head (and to date, not an interest of mine).   I don't want to admit that I'm too lazy to "do the research and do the math",  so with all this I've got a couple of questions I hope someone help me with.

1.  Is there a relationship between a vawts height vs Width?
2.  Is there a relationship between the number of vanes and it's rotational speed?
3.  Since the river current will all ways be flowing from the same direction, would that effect blade profile?
4.  Since the change of flow rate (mph) from max to min (drought to flood) would be only a few miles per hour
     would this change the ideal profile?
5.  Would the density difference of water vs air effect the vane profile and number?
6.  What am I forgetting to ask? 

Yes,  I know I've made no mention of an alternator, or a gear box.  There's plenty of time for that.  Maybe a right angle gearbox on top of it, and the drive shaft running to shore and alternator.
I envision this VAHT being "up side down"  where it's bottom bearing would be anchored on the river bottom.  it's top bearing (and genny) would be supported by supports from shore.   For now,  thinking the bearings would be UHMW or a plastic to be determined.    The center (drive) shaft will be made from a 1 1/4in di bronze pipe salvaged from a air cylinder.

In the past I was thinking of a large diameter water/paddle wheel floating on pontoons.  But I've had visions of finding a kid wrapped around it.
A vaht would be easier to "kid proof".

yes/no?

ax7
Mark

[taylorp035]

Sounds like fun. At 1000x more dense than air, getting the power that you want will be easy.

I would make sure your vanes are string enough to withstand the large amounts of torque.

How much power do you want? 100, 1000watts?

I am sure people with real experience will chime in here.

[TomW]

Try a search for Gorlov turbine. About exactly what you are talking about but a helix kinda deal for submerged use?

Just a hint.

Tom

[jlt]

try this site.It has darrieus under water turbine mounted on a row boat.www.althydrosolutions.com

[12AX7]

Taylorp035
I know that this idea isn't with out issues that need attention.  I am very aware of the dynamic forces involved,  just standing in the current at "low level" times (and when the water is at it's warmest) is a trick.
I think that I'll be building a couple of mock ups with which I'll play around with structural bracing ideas. 
Of all the problems to over come this is the one I worry about the most.  I need to make it as light weight as possible so I can handle it with out heavy machinery.

As far as how much, I have to respond with..  "how much can I get?".

and yes, I hope others will pop in and tell me how to do this!

TomW
I am aware of Gorlov and his turbine,  as a matter of fact I think that I am the one that first brought his name and idea to the board.   In my "new camera, it's digital" thread (started back in May of 06) I posted a pic of him along with one of his "heilacal turbines".
Back then I had a few chats with Zubbly (RIP).  He checked out Gorlov's site along with Verdant Power.  It was his suggestion that not having the depths they were operating at that I'd be better off with something with a wider blade profile. 
Back then there was less talk about VAWTs and Zubbly was in agreement that a larger sized water wheel would have a better chance of capturing the power in a shallow location.
Damn!   I miss that guy!  (some day I'm going to work up the courage and start asking who, if anyone was on the "inside" with him,  and willing to share where Wayne got the nick "Zubbly")
Anyhow, the issue with Grolovs system is that he hasn't shared his plans.
I'd also like to mention that it was Zubbly that thought that even in the limited conditions (no drop to speak of) I'll be working with that there was plenty of power to capture. 

jit
I'll have to check out that site.  I have already checked out a large number of under water turbines but almost all of them are smaller diameter and are rated at a low output.  I'm hoping to get better than a few hundred watts.
At least,  when the river is at it's high point.
Also, the submersible types would not take advantage of when the river is at it's highest and fastest flow.
My idea would allow the turbine to output power at drought conditions, and increase output as the level rise.
At least,  it's what I hope!

ax7
Mark

[12AX7]

Well, after seeing this link    http://www.absak.com/catalog/product_info.php/cPath/33_89_90/products_id/1098

I see that someone is "doing it"..

So,  again I'll ask if anyone would care to suggest a blade profile?

ax7
Mark

[12AX7]

At $28,000.00  a 5 KW turbine is a bit pricey for me.   In their write up they claim it could pay for it's self in as little as two years.

I'm not sure I believe that,  I wonder if it's 5 KW rating is also a bit shady?

ax7
Mark