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

I am missing a picture of your design. I think of his design as one tube with a "screw" inside. "... one tube wrapped around from top to bottom" I can't picture. Is the tube in the form of the screw? Yes six tubes would move six times the water, requiring six times the force, but the force would still be reasonable for one person.

 

Maybe he is talking about the pitch.

 

I don't see how 6 tubes would move more water if thickness of tubes walls is taking more place than a screw design.

 

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

Hi,

Any rotary thing will compress air. If there is an air flow, then there must be compression. That is, input output pressure differential.

You need to establish some comparative limits though in order to make this conversation mean anything reasonable.

For example, if i had a one thread screw would that be better than a 100 thread screw. There is no comparison until we set limits on things like diameter. If the diameters have to be the same for each construction then we have something, and if the total inside diameters have to be the same then we have something there too.
For example, 10 straight pipes of length 1 unit will have more inside surface area than one large pipe with the same total cross sectional area as all the smaller pipes added together.
For example, if we allow more pipes without any restrictions then if we add 100 pipes of diameter 1 of course they will pass more water than 1 pipe of diameter 2.
So to really compare you have to set some limits.
Maybe a limit on the speed or horse power too. If they both have to operate at 1 horse power then the construction with the highest resistance looses.
On the other hand, there may be a limit on the diameter of the whole thing so it can fit in a certain space. We cant have a 100 foot diameter in a space that only allows a 10 foot diameter, and since pipes wound around a central core have to take up at least 2x diameter, that means that multiple pipes would probably be used in order to meet the flow requirements...which brings up that constraint as well...the flow requirement.

What you are talking about is really an optimization problem, but with all optimize problems there are always constraints or else it's just a "do whatever the heck you want to do" problem.

Multiple screw threads on the same screw are often called "flutes". They can sometimes only wrap once around the screw body for example. That makes them 'fast'. Many drill bits have two flutes.

 

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

The TS was talking about moving water in the original post. And even though the air compressors you referenced are "screws" they are much different than an Archimedes water screw. the air compressors use two inter leaved screws of a tapered diameter and variable pitch in a housing/body that compresses the air as it moves longitudinally. Way different than an Archimedes screw.

 

I am missing a picture of your design. I think of his design as one tube with a "screw" inside. "... one tube wrapped around from top to bottom" I can't picture. Is the tube in the form of the screw? Yes six tubes would move six times the water, requiring six times the force, but the force would still be reasonable for one person.

if you can imagine a solid or hollow piece of tube say 50mm in diameter and say 600mm long with a 10mm hollow plastic pipe fixed at the bottom end of the large tube at 45 degrees to the length and then wound at equal distance all the way up as a spiral (there are similar ones shown on youtube) tilt the large tube at 45 degrees and turn in a direction so as the bottom of the small tube scoops up water from a basin and eventually brings the water up the tube to the top and it pours out. my thought is this .if the large tube is 50mm in diameter and one small pipe is 10mm in diameter then if four more 10mm tubes were added side by side copying the same spiral fashion then I assume five times more water would be picked up and ejected at the top with the same revolutions ?

 

This is a job for Carnack.

 

This is a job for Carnack.

hi is carnack watching this

 

Sorry my friend, but I can not understand hardly anything of what you are saying. I shall move on. Good luck to you.

 

I think I understand Post 26 (and nothing that the OP described before that)

I picture this like a hollow Fusilli pasta coil within a larger tube.

I would say that the answer is - yes, five smaller pipes within the bigger tube will shift 5 times as much water as the single tube assuming the same rotation rate

It will require 5 times as much effort to turn the screw.

The above ignores things like friction, leakage etc for the sake of simplicity. It also ignores the fact that some water will be trapped behind the tube, increasing the flow, but then presumably 5 times as much water might (or might not) be trapped behind 5 tubes.

I suspect (only a guess as I have not done the maths) a single spiral taking up the whole of the tube might shift water at a faster rate still, but the small pipe within a larger one is presumably chosen because it is easier to make than a traditional Archimedes screw.

This is my take, anyway.... I may still be mis-understanding...

Oh.... and I am not sure in my head that 5 tubes will fit with the dimensions that you gave, unless you have a very long tube at a shallow angle and a very elongated spiral, but I think I get the principal. Maybe say two tubes - just to make my brain happy

 

I think I understand Post 26 (and nothing that the OP described before that)

I picture this like a hollow Fusilli pasta coil within a larger tube.

I would say that the answer is - yes, five smaller pipes within the bigger tube will shift 5 times as much water as the single tube assuming the same rotation rate

It will require 5 times as much effort to turn the screw.

The above ignores things like friction, leakage etc for the sake of simplicity. It also ignores the fact that some water will be trapped behind the tube, increasing the flow, but then presumably 5 times as much water might (or might not) be trapped behind 5 tubes.

I suspect (only a guess as I have not done the maths) a single spiral taking up the whole of the tube might shift water at a faster rate still, but the small pipe within a larger one is presumably chosen because it is easier to make than a traditional Archimedes screw.

This is my take, anyway.... I may still be mis-understanding...

Oh.... and I am not sure in my head that 5 tubes will fit with the dimensions that you gave, unless you have a very long tube at a shallow angle and a very elongated spiral, but I think I get the principal. Maybe say two tubes - just to make my brain happy

 

I would like to make it clear the smaller tubes are wrapped around the outside of the larger tube thanks.... kev

 

if you can imagine a solid or hollow piece of tube say 50mm in diameter and say 600mm long with a 10mm hollow plastic pipe fixed at the bottom end of the large tube at 45 degrees to the length and then wound at equal distance all the way up as a spiral (there are similar ones shown on youtube) tilt the large tube at 45 degrees and turn in a direction so as the bottom of the small tube scoops up water from a basin and eventually brings the water up the tube to the top and it pours out. my thought is this .if the large tube is 50mm in diameter and one small pipe is 10mm in diameter then if four more 10mm tubes were added side by side copying the same spiral fashion then I assume five times more water would be picked up and ejected at the top with the same revolutions ?

Five tubes widely spiraled or one tube tightly spiraled, the amount of water in motion is about the same.

 

Five tubes widely spiraled or one tube tightly spiraled, the amount of water in motion is about the same.

but the pick up on one tube on one revolution must be less than than the pickup on five tubes in one rev ?

 

but the pick up on one tube on one revolution must be less than than the pickup on five tubes in one rev ?

True. One tube requires more cranks before water starts coming out.

 

True. One tube requires more cranks before water starts coming out.

Huh? Each added tube will take the same number of turns as a single tube will. But the Archimedes screw is still a inefficient way of moving water.

If this HAS to be done by human power there a many ways that it could be done. And at least one way that it could be done with no electricity but not human powered, the ram pump. http://www.waterencyclopedia.com/Po-Re/Pumps-Traditional.html

 

I agree that the Archimedes Screw is an inefficient way of moving water. But it has some benefits:

• Simple to make
• No seals required
• Works with low rotational speed (good when human powered)

Same benefits when used as a water powered generator - except for low speed - which is a disadvantage for electricity generation.

It is inefficient because of friction in the tube - resistance to flow.

BTW: the same is true for the wind turbine idea. I don't think anything can beat the common 3-bladed wind turbine for efficiency and catching the greatest wind area (hence power) with the smallest amount (and weight) of materials. It is interesting to note that on a standard wind turbine the blades are moving far faster than the wind speed over most of their length. This won't come as a surprise to anyone who has done any sailing where the boat moving faster than the wind is quite possible!

 

But the shaduf and bucket wheel would be also simple to build and move a higher volume of water than the screw in a equal time period.

 

Not sure about a shaduf (or Shadoof - I've just learnt a new word!). The Bucket wheel I reckon will be less efficient than the AS due to the amount of splashing and turbulence created. Also tends to lift higher than needed due to tipping the buckets.

AS fairly simple to build these days - provided you have enough flexible large plastic tubing. Harder in ancient times - would need some good carpentry skills! And presumably a multi-helix (a number of separate tubes) gives a more continuous water flow.

Engineering research project for someone?

 

The Bucket wheel I reckon will be less efficient than the AS due to the amount of splashing and turbulence created.

Hi, how big of a tube would be needed to move the same volume of water as a single 1Gal bucket on a bucket wheel? And there would be many of them on a wheel.