What Is the Pressure After a Hydro Turbine?

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    Pressure Turbine Water
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Discussion Overview

The discussion centers on the pressure conditions following a hydro turbine in a hydro dam setup, particularly focusing on whether the pressure can be assumed to be atmospheric when water discharges into the atmosphere or if other factors influence this pressure.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose that the pressure after the turbine could be atmospheric if the water flows directly into the atmosphere.
  • Others argue that the pressure depends on the configuration of the system, specifically whether there is a submerged tailrace.
  • A participant questions the rationale behind discharging water below the surface of the river, suggesting that maximizing the pressure drop across the turbine would be preferable.
  • It is noted that if the discharge occurs in a river, the pressure difference would be influenced by the relative water levels of the reservoir and the river.
  • Another participant clarifies that if the discharge is above the river, the pressure difference would be based on the reservoir water level compared to the discharge level.

Areas of Agreement / Disagreement

Participants express differing views on the impact of system configuration on pressure after the turbine, indicating that multiple competing perspectives remain unresolved.

Contextual Notes

The discussion highlights the importance of specific system configurations, such as the presence or absence of a submerged tailrace, and how these configurations affect pressure calculations. There are also assumptions about the relationship between reservoir and river water levels that remain unexamined.

Pim_Verwoerd
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Homework Statement
Pressure loss due to turbine
Relevant Equations
P = Q * dP. Bernoulli
For an engineering project we have to make an energy storage system. We thought of something like a hydro dam. We were having a discussion about the pressure after the turbine in the hydro dam. The water immediately flows into the atmosphere ( so it falls down into a lake ). Can we then safely assume that the pressure over there is the atmospheric pressure? Or is there a different pressure field because of the turbine?
 
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I think it depends on the actual configuration. Does it have a submerged tailrace? Then not Patm.

440px-Hydroelectric_dam.svg.png
 
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gmax137 said:
I think it depends on the actual configuration. Does it have a submerged tailrace? Then not Patm.
That's interesting. Why would you discharge below the surface of the river? It seems like you'd want to maximize the pressure drop across the turnbine...
 
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gmax137 said:
I think it depends on the actual configuration. Does it have a submerged tailrace? Then not Patm.

View attachment 289165
No it doesn't have a submerged tailrace. The water that comes out of the turbine comes out into 'clean' air.
 
Pim_Verwoerd said:
No it doesn't have a submerged tailrace. The water that comes out of the turbine comes out into 'clean' air.
Then the pressure (in the clean air) is atmospheric. It can't be anything else.
 
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berkeman said:
That's interesting. Why would you discharge below the surface of the river? It seems like you'd want to maximize the pressure drop across the turnbine...
If the discharge is in the river then the pressure difference would be the difference between the reservoir water level and the river water level.

The head increase from a lower discharge is offset by the river water above the discharge.

If the discharge is above the river, the pressure difference is the difference between the reservoir water level and the discharge level.
 
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