Re: Building a hydrodynamics water tunnel for surface water wheel testing.

[BaNe_TEK]

I need to simulate the flow of a river, to do small scale hydrodynamics testing on a partially submerged water wheel / paddle wheel design. The typical water tunnel setup will not work, because we are interested in the flow near the surface. The water wheel is half in the water, and half out. Anyone have any suggestions? I have been trying to use a long open topped gutter and pump the water in one side, and out a drain on the other. But, I get turbulence reflecting backwards because the water is bouncing back before exiting out of the drain port.

How can I get a smooth flow / current, like a river with both air space and a water surface, without using a closed system that is based on water pressure? In my current open topped gutter setup; should I be using an open end hose pushing the water in the proper direction, or should I use a diffused filter? Or will both get reverberation flow regardless? Thanks so much in advance. Appreciate the advice.

 

[johnbbahm]

This is just an Idea, (As I don't do any hydrodynamics.) but if you had an accumulator tank that the pump filled from the bottom, and the gutter flowed off the smother top.
This might isolate some of the turbulence.

 

[mushinskull]

I think you need a combination of the Accumulator filled from the bottom as johnbbahm mentioned to get a smooth flow down the channel/gutter, and remove the drain port such that the channel/gutter drains freely into another storage container to eliminate that turbulent backflow condition.

Rinse and repeat.

 

[BaNe_TEK]

Thanks guys, and I think that would probably work. The combination of the two ideas. But, we would have needed a much larger pump with an open ended channel.

However, we actually went with a bottom mounted design now because we are deploying in a tidal basin and our generator units will be under tremendous forces. Shortly, we will receive our financing and many qualified engineers will conduct proper testing on our tidal hydro kinetic turbine generators. Thanks again for the efforts! Much appreciated.

- BaNe

 

[Jorris]

BaNeTEK,

Very interesting, since I am also developing a free-surface water tunnel aka a channel. My plans are similar to the drawing of Mushinskull, but I will use a horizontal channel. To reduce turbulence, all tunnels have a flow straightener (honeycomb) in a large inlet section, then a contracting nozzle and then the test section.

So, how is your channel doing? Can you tell me some more about it (flow speed, size of the test section,...)? And where do you work?