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
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[ Parent ]
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[ Parent ]
