6 ms·

Any undergraduate intro to fluid mechanics textbook will cover this material thoroughly. Looking at my bookshelf I have "Fluid Mechanics" by Frank M White from

by na85 4y ago

Any undergraduate intro to fluid mechanics textbook will cover this material thoroughly. Looking at my bookshelf I have "Fluid Mechanics" by Frank M White from third year fluids back in the early 00s which treats this material in a chapter called Turbomachinery, building upon the preceding 10 chapters or so. If you don't want to deal with calculus you can get most of the way there with the Bernoulli equation and friends. Edit: this looks pretty good after a cursory glance: http://brennen.caltech.edu/fluidbook/ http://brennen.caltech.edu/fluidbook/

otter-rock 4y ago
Fundamentals of fluid mechanics by Munson et al is also good.
timr 4y ago
If you only get 26 feet of head, how do they manage to pump water from (say) the water tunnels that are hundreds of feet under Manhattan? Is it just that the pressure in the tunnels is well above 1atm?
- woodruffw 4y ago
  The pressure in NYC's water tunnels brings the water up to about the 6th storey[1]. Beyond that additional pumps and tanks are needed, which is why NYC's skyline is covered in wooden water tanks (except for the newer buildings, which often have internal metal ones). [1]: https://untappedcities.com/2021/01/22/how-does-water-tower-work/ https://untappedcities.com/2021/01/22/how-does-water-tower-w...
  - timr 4y ago
    That's not what I'm referring to. Yes, the water system is pressurized (as are all), but the tunnels themselves are ~500 feet below ground [1][2]. Water is pumped to valve chambers which are themselves far (~250 feet) below ground, then again to the surface. The head pressure on a 500 foot column of water would be over 200psi. This article [3] says that the first leg of water tunnel three runs at over 300 psi, though, so maybe that's the answer. It just seems crazy. [1] https://en.wikipedia.org/wiki/New_York_City_Water_Tunnel_No._3#:~:text=upstate%20water%20supply.-,Water%20Tunnel%20No.,completed%20until%20at%20least%202026 https://en.wikipedia.org/wiki/New_York_City_Water_Tunnel_No..... [2] https://www.theverge.com/2013/10/19/4853636/underground-with-manhattans-new-water-tunnel-three-photo-essay https://www.theverge.com/2013/10/19/4853636/underground-with... [3] https://www.baltimoresun.com/news/bs-xpm-1998-08-21-1998233084-story.html https://www.baltimoresun.com/news/bs-xpm-1998-08-21-19982330...
- wishawa 4y ago
  Pumps might only be able to suck water up 26 inches, but there is no such limit on how high they can push water.
  - bruce511 4y ago
    I believe the suck-height limit is more than 26 inches. From memory (it's been a long time) the theoretical maximim for 1 atmosphere is 10m. Practically, because of inefficiencies a lot less. Annecdotally I have a well-point (pump at top) that lifts water 2 to 3 metres. And I have an agricultural pump that sucks about 4m,and then pushes water up a hill the next 50 vertical metres or so. And its a pretty small pump.
  - na85 4y ago
    >there is no such limit on how high they can push water. Of course there's a limit. If there were no limit we'd have infinite free power generation.
    - zaroth 4y ago
      You’re missing the fundamental difference in the power vs distance curve. In the case of sucking water, it flatlines and no amount of additional power can move the water another inch once you’ve exceeded the pulling power of a perfect vacuum. Without looking up the actual equation, I would guess that this is never true (or at least practically never) when pushing water, because you’re not limited by atmospheric pressure. When pushing you have to provide enough energy to move all the water in front of you, but if you do provide that energy the water will move. At some point I suppose the pressure will get so high the water will solidify in the pipe though?
      - na85 4y ago
        >You’re missing the fundamental difference in the power vs distance curve. You're missing the fundamentals of physics. >At some point I suppose the pressure will get so high the water will solidify in the pipe though? Before (way way way before) the water solidifies you will reach the maximum pressure that a given pump can deliver. If you think the little 1/2 horse sump pump you can buy at home Depot will push a column of water up to the stratosphere then I have a bridge to sell you.
- s0rce 4y ago
  Put the pump at the bottom and push the water up, don't suck it up from the top. Same way with deep wells.

by na85 4y ago

otter-rock 4y ago

Fundamentals of fluid mechanics by Munson et al is also good.

timr 4y ago

If you only get 26 feet of head, how do they manage to pump water from (say) the water tunnels that are hundreds of feet under Manhattan? Is it just that the pressure in the tunnels is well above 1atm?

woodruffw 4y ago
The pressure in NYC's water tunnels brings the water up to about the 6th storey[1]. Beyond that additional pumps and tanks are needed, which is why NYC's skyline is covered in wooden water tanks (except for the newer buildings, which often have internal metal ones). [1]: https://untappedcities.com/2021/01/22/how-does-water-tower-work/ https://untappedcities.com/2021/01/22/how-does-water-tower-w...
- timr 4y ago
  That's not what I'm referring to. Yes, the water system is pressurized (as are all), but the tunnels themselves are ~500 feet below ground [1][2]. Water is pumped to valve chambers which are themselves far (~250 feet) below ground, then again to the surface. The head pressure on a 500 foot column of water would be over 200psi. This article [3] says that the first leg of water tunnel three runs at over 300 psi, though, so maybe that's the answer. It just seems crazy. [1] https://en.wikipedia.org/wiki/New_York_City_Water_Tunnel_No._3#:~:text=upstate%20water%20supply.-,Water%20Tunnel%20No.,completed%20until%20at%20least%202026 https://en.wikipedia.org/wiki/New_York_City_Water_Tunnel_No..... [2] https://www.theverge.com/2013/10/19/4853636/underground-with-manhattans-new-water-tunnel-three-photo-essay https://www.theverge.com/2013/10/19/4853636/underground-with... [3] https://www.baltimoresun.com/news/bs-xpm-1998-08-21-1998233084-story.html https://www.baltimoresun.com/news/bs-xpm-1998-08-21-19982330...
wishawa 4y ago
Pumps might only be able to suck water up 26 inches, but there is no such limit on how high they can push water.
- bruce511 4y ago
  I believe the suck-height limit is more than 26 inches. From memory (it's been a long time) the theoretical maximim for 1 atmosphere is 10m. Practically, because of inefficiencies a lot less. Annecdotally I have a well-point (pump at top) that lifts water 2 to 3 metres. And I have an agricultural pump that sucks about 4m,and then pushes water up a hill the next 50 vertical metres or so. And its a pretty small pump.
- na85 4y ago
  >there is no such limit on how high they can push water. Of course there's a limit. If there were no limit we'd have infinite free power generation.
  - zaroth 4y ago
    You’re missing the fundamental difference in the power vs distance curve. In the case of sucking water, it flatlines and no amount of additional power can move the water another inch once you’ve exceeded the pulling power of a perfect vacuum. Without looking up the actual equation, I would guess that this is never true (or at least practically never) when pushing water, because you’re not limited by atmospheric pressure. When pushing you have to provide enough energy to move all the water in front of you, but if you do provide that energy the water will move. At some point I suppose the pressure will get so high the water will solidify in the pipe though?
    - na85 4y ago
      >You’re missing the fundamental difference in the power vs distance curve. You're missing the fundamentals of physics. >At some point I suppose the pressure will get so high the water will solidify in the pipe though? Before (way way way before) the water solidifies you will reach the maximum pressure that a given pump can deliver. If you think the little 1/2 horse sump pump you can buy at home Depot will push a column of water up to the stratosphere then I have a bridge to sell you.
s0rce 4y ago
Put the pump at the bottom and push the water up, don't suck it up from the top. Same way with deep wells.