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I am making a testing facility for pumps. This facility has to be able to handle 500 m3/h with at little turbulence as possible. The basin itself is 5 meters long, 2,5 meters wide and 2 meters tall. The water level in the basin is kept at 1,9 meters.

The basin is designed in two sections: the first is where the discharge flow comes into the basin (pipe ends about 1 meters in from the bottom). In that area the water flows freely.

After that it has to flow over the retaining wall (1.7m high), which should create a somewhat uniform flow.

overview

Are there better solutions to do this?

One other idea I have is a retaining wall somewhat like this:

wall idea

This makes for three plates with cutout stripes.

The idea behind this is to have a more uniform flow across the entire basin instead of a overflow, making it create a small bit of turbulence there.

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  • $\begingroup$ Do you have more specific requirements? Can you suggest an adequate Reynolds number or criteria for turbulence? $\endgroup$ – willpower2727 Mar 30 '16 at 12:33
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    $\begingroup$ Is the retaining wall just there to smooth flow? What's the point of trying to eliminate turbulence in your tub - you're almost certain to have turbulence at the suction of the pump at those flows. $\endgroup$ – Chuck Mar 30 '16 at 12:56
  • $\begingroup$ @willpower2727 I have been looking into Reynolds, but i find it hard to come up with a good solution to make that calculation. What would be a good goal? should i be using the area above the wall as surface area? $\endgroup$ – Arjo Mar 30 '16 at 13:02
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    $\begingroup$ @Arjo I rarely do fluid calculations, but you could look into finding a hydraulic diameter for the tub:en.wikipedia.org/wiki/Hydraulic_diameter $\endgroup$ – willpower2727 Mar 30 '16 at 13:08
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    $\begingroup$ I'm hardly an expert, but I would consider replacing the upper portion of the solid partition (above the level of the discharge pipe openings) with a couple of layers of some sort of metal mesh or screening. I assume the tank is kept fairly full (1.5 - 1.8 m) during a test. $\endgroup$ – Dave Tweed Mar 30 '16 at 14:15
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Assuming you are wanting to minimize turbulence in the region of the pump, you would probably need to use flow straighteners somewhere upstream of the pump. You would have to study the optimal diameter and length of the straighteners. MIT simply used drinking straws to do this in a wind tunnel. Here are a couple of the more well known papers on the subject:

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In wind tunnels usually meshes and/or honeycombs are used to reduce turbulence.

However, to really achieve low turbulence it's probably not enough to add a single component to your facility. I rather suspect you need to evaluate the overall design. Some kind of diffusors at the pipe end(s) might be helpful. If you look at the flow behind bridge pillars, you can see that turbulence can be preserved over long time scales also in water.

This is non-trivial.

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