water falling

Hello Guest,

Extend the PVC pipe down to below the surface of the water in the tank. If you can't do that, get it as close as you can to the water surface in the tank.

Mike

Bring the pipe down to water level. Then put some large baffle in the bottom to reduce the velocity so that the turbulence stays inside the smaller tank (at the end of pipeline)

If your problem is agitating the tank water place a 90 degree elbow at exit of water pipe so water turbulence is at top of tank only. You could also install a diffuser that spreads the exit water over a larger area to cut down on turbulence. Since I am not 100% certain of your particular system this is just a few suggestions.

It sounds like the current exit is 20 feet above the tank - if that's so - you could hang a plastic link chain from the current exit so that it dangles in the tank - the water velocity will reduce because it will have to work its way down the chain to reach the tank instead of just falling straight in.

To secure the chain to the current exit, tie a knot in the top end of the chain so that the knot is big enough to jam in the downpipe diameter.

The bigger the chain, ie, the more surface area of the chain, the more volume it will handle.

I presume that you're doing it to stop the falling water splashing outside the tank when the fall is heavy, and for some reason you don't want to extend the pipe, is that right?

Some Japanese houses have such chains instead of downpipes because the Japanese like the appearance of falling water. Usually they can be steel but that requires a good strong fixing and I assume you just have a plastic downpipe, and if that's so, then a steel chain would be inappropriate in your case.

Connect a hydro-electric unit to the end of your penstock. Almost all the velocity will go into turning the turbine and your volume won't change plus you'll have electricity.

Let's look at the basics here --

Your problem is that there is unwanted mechanical energy, both velocity energy potential energy in the inflow liquid. You would like to disipate that energy into internal energy before it reaches the main body of water in the tank to disipate via the unwanted turbulence.

The other issue is exactly what kind of turbulence in the tank is unacceptable? Is the problem large volume turbulence from a single stream falling directly into the water? Or is part of the problem surface splashing from water splashing off the tank walls from a high velocity inflow? You didn't mention the flow rate(s) through the 8 inch line.

Note here that a steady inflow "rain" of water falling uniformly on the surface would produce primarily surface turbulence. A nozzle or distribution system (maybe too complex) would disipate much of the velocity energy and to the extent that it flowed down the walls of the tank would romove a big part of the potential energy.

If none of the easy suggestions already mentioned work well consider this:

Assuming the tank has a watertight sturdy roof a fabricated outlet structure with upward facing nozzles directing "jets" or baffles pointed at the area of the tank roof as well as the upper sides. Don't forget "doors on the sides or bottom to facilitate maintenance. This is the kind of thing that could be easily fabricated from steel or stainless steel or even a fiberglass/epoxy structure with construction like a small boat and attached to or suspended from the roof with a connection to the inflow pipe. The idea is to get a "rain effect" distributed over as much an area of the tank as possible.

Ed Weldon

I solved a similar problem but on a smaller scale but putting a piece of foam rubber where the water entered. I got the idea from a local theme park,, where 'slugs' of water are fired in an arc over peoples heads, to dissappear into the ground without a splash. It was a very open mesh lattice type foam rubber on the landing area.

It may not work for you to have foam in the water, but a mesh lattice, layer on layer, may do the trick. It could float on a dingy, only anchored to the sides or bottom.

Jim