hi all I was looking at an Archimedes screw with one tube wrapped around from top to bottom moving water upwards and I had a thought, what if there were more tubes wrapped around ,say six, would this increase water movement without increasing strain on the screw or is this a stupid question? thanks... kev

 

Lifting more water requires more energy to turn the screw. The extra water weight will also increase wear and tear on the screw bearings.

 

Lifting more water requires more energy to turn the screw. The extra water weight will also increase wear and tear on the screw bearings.

thanks for your reply but would it be better than using six one tube screws thanks

 

The extra tubes just add extra complexity without increasing efficiency, so a single tube is likely better for most applications.

 

The extra tubes just add extra complexity without increasing efficiency, so a single tube is likely better for most applications.

thank you

 

Depending on your application, multiple small tubes can have many advantages over one large tube.

You may throttle.

Higher reliability.......if one tube fails, you may still pump.

On demand maintenance.....may repair one tube while still pumping.

Cost.....off the self standard tubes might be cheaper than custom large tube.

 

Flow resistance varies inversely with the fourth power of the tube cross-sectional radius, so that would be a factor affecting efficiency. Small tubes are more likely to get blocked than a large one.

 

The extra tubes just add extra complexity without increasing efficiency, so a single tube is likely better for most applications.

There are one-bladed propellers for airplanes -- a counter weight balances it. With slow speeds and low power, they are very efficient. However, I have never seen a turbojet with a single bladed turbine. I think the best number of flights for a screw depends on several factors.

That is not to say that for pumping water I disagree with using only one or two flights. For air, it is often a different story.

John

 

Why use an Archimedes screw at all? Are they as efficient as a standard rotary pump? There must be a reason they aren't used since rotary pumps were invented.

 

I recall screw pumps used on board for luboil, not sure if for diesel or fuel oil and maybe fresh water.

 

Why use an Archimedes screw at all? Are they as efficient as a standard rotary pump? There must be a reason they aren't used since rotary pumps were invented.

my original idea was to use an Archimedes screw in a a reducing conicle tunnel as a turbine would this work... thanks

 

Why use an Archimedes screw at all? Are they as efficient as a standard rotary pump? There must be a reason they aren't used since rotary pumps were invented.

They most certainly are used, even for compressible things like air. A lot of high-flow air compressors (>25 HP) are screws.

As for moving corn and other products, rotary compressors don't work so well. They also don't work that well for jack screws when the purpose is effectively to move a nut longitudinally.

John

 

"I had a thought, what if there were more tubes wrapped around ,say six, would this increase water movement without increasing strain on the screw"

I think I have mis-understood you.

Could you restate that for me? What do you mean by "wrapping more tubes around?"

 

They most certainly are used, even for compressible things like air. A lot of high-flow air compressors (>25 HP) are screws.

As for moving corn and other products, rotary compressors don't work so well. They also don't work that well for jack screws when the purpose is effectively to move a nut longitudinally.

John

but if the the screw was formed in a cone shape would this compress air drawn in ?

 

"I had a thought, what if there were more tubes wrapped around ,say six, would this increase water movement without increasing strain on the screw"

I think I have mis-understood you.

Could you restate that for me? What do you mean by "wrapping more tubes around?"

if one tube is wrapped from bottom to top why not have more tubes in a screw fashion gathering more water on each revolution ?

 

What do you mean......one tube is wrapped?

Can you provide some pictures.......labelled........what is wrapped.

 

If you mean.....can more than one spiral be put on the axle.....................no.

 

my original idea was to use an Archimedes screw in a a reducing conicle tunnel as a turbine would this work..

Don't know about the conical tunnel, but here's a local hydroelectric use of a screw.

 

if one tube is wrapped from bottom to top why not have more tubes in a screw fashion gathering more water on each revolution ?

I think you completely missed my point. Multiple screws work, but they are usually coaxial. No need to have the screws operate on separate axes.

John

 

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