Kaplan Turbine

[WXYZCIENCE]

I have been thinking about this idea for a long time. I acquired a used but good condition stainless steel impeller from a Sea-do. I also had a stainless steel funnel which was attached to the impeller.







The next picture is my design idea. The housing will be cast from resin to start. The swirl gates will be adjustable in this design.







I want to use the unit with a very low head. Has anyone every built a unit similar to this one? Any info on flow volume / vs power through this type of runner would be welcome.
Joseph.

[Flux]

No idea of the size. Propeller turbines are not common for micro hydro as the very small ones tend to block up.

If that thing is as big as it looks then you will need a very large flow of water. As long as you can supply that then it should work fine.

It will not be a Kaplan ( variable pitch blades) so you will need to work round its speed and load characteristics.

You need to be up in the 100 gallons/minute region for a small reaction turbine.

Flux

[hvirtane]

I know a small self made Kaplan turbine,

which is in use with a friend of mine.

It is about 1 kW and with high technologies

such as automatically adjusted vanes.

The flow head is there low, a few meters.

I think that the good performance with

that machine is because of the really

high level workmanship of the machine.

In general as far as I know it is easier

to make a crossflow turbine than a well

working Kaplan turbine.

I will ask my friend to check this discussion

and about further details of his Kaplan.

- Hannu

[Flux]

Yes hannu I think you are right. To produce any satisfactory small reaction turbine you have the effects of scale working against you.

The engineering needs to be a high standard, bearing friction, clearances surface finish and the problems of blocking the small dimensions are all a big factor.

Impulse turbines are not really low head devices and are not used as such in large sizes but they can still be efficient at low head if you can build a low speed alternator. They seem much more practical in the low flow region ( 100 gpm and below).

For anything above 6" diameter then the reaction turbine should work out the better option if you can build it carefully.

Flux

[WXYZCIENCE]

Flux, the impeller is five inches in diameter. The unit will be first tested in a creek that passes through my land. The volume of the spring run off is huge and every year I have wanted to test this idea.Yes the true kaplan does have variable pitch blades. This will probably limit me to small output.


as the very small ones tend to block up


I will use a culvert attached to the output this will create the vaccume needed to keep the runner free. Every year I see the water flowing from that 5 foot opening for almost a month. Lots of power there.
Joseph.

[WXYZCIENCE]

Hannu, the engineering of the impeller by Bombardia is what I am using. It is made of high quality stainless. The input vanes will be somewhat of a challenge because they have to be adjustable. Also the water flowing through the runner has to be very uniform.
I would be very interested in your friends design that you speak about. Thank you for your input.
Joseph.

[Gog]

In my own creek I would expect to see trash (long thin ferny stuff here ) building up on the gates,

 rather than the runner. Assuming there is a bit of clearance at the blade tips.

I think filtering will have to be good.

At this size ,It may be  that getting your scroll case close enough down to the runner will give you a swirl that will give

 an angle of attack that is good enough without the gates and their associated maintenance.

I suspect though ,that my idea of good enough and yours are miles apart , I'm pretty lazy.

all the best

Keith

[WXYZCIENCE]

Keith, thanks for your input. Debris will be a problem I agree. This is all new to me and I enjoy challenges. The fun is in the doing. Something like Calvin and Hobbs and his propeller hat.
Joseph.

[Ungrounded Lightning Rod]

Look into coanda effect debris screens.  They let virtually all the water through with very little pressure or velocity loss while the debris slides off the surface without penetrating or hanging up on it.

[dimitar]

Hi ,

Here some formulas for Kplan turbine flow

where Q is flow, A is swept area, m2, g-gravity constant, H- head, m

[acme12]

Hi, I have few questions for very low head (under 1 m) propeller turbines.

My friend has a software PropCad that could generate ducted boat propellers. Should hydro propeller for generating power be made with characteristics for boat propellers by use the mirror hydro foils?

What characteristics  should be used for low head propeller, blade number,hub diameter, expanded BAR, blade thickness distribution, nominal pitch  or TSR...?

Thanks for help.

Marko