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Water Flow through a jet

Question asked by 1-LSB132 on Aug 31, 2009
Latest reply on Sep 2, 2009 by Joe Galliera

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My team is currently running silumations on safety valves and have hit a snagg. We are basically running a simulation on a water jet hitting a wall. Look at attached pdf named example(these are test values not real ones). We have it set up with Pressure at the Inlet and Pressure at the outlet As long as Dimension A is around .100 " the everything looks good, but when we increase A, region B gets a negative pressure and velocity out increases drastically. any advise on solving this would be helpful.

Loic Ancian Sep 2, 2009 6:14 AM

Correct Answer

Hi,

Maybe there is some cavitation??

If you check "cavitation" option you should not get negative values any more and see if cavitation area is important or not.

See the reply in context

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Example.PDF22.3 KB

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Rich Bayless Aug 31, 2009 3:03 PM

Hello James,

What happens if you set a flow rate (mass or volume) on the inlet, along with a pressure at the outlet?

Cheers, Rich.

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1-LSB132 @ Rich Bayless on Aug 31, 2009 3:50 PM

Rich,

We are not sure of the flowrate at the inlet because it is a new design. We have made some assumptions and guessed the flowrate based on older valve data, and it does work, but the flowrate is still in question because on 2 other sizes of valves the flowrate has increased and decreased based on the changes we have made and that changes the way we look at the dimensional changes made.

Thanks James

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Rich Bayless @ 1-LSB132 on Sep 1, 2009 9:34 AM

Hello James,

can you post more details, such as the actual pressures you are applying at inlet and outlet?

Also, post screenshots of your computational domain, and perhaps a cut plot or three? Trajectories perhaps?

Also include your version, such as SW2009 SP2.1, or whatever.

Thanks, Rich.

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1-LSB132 @ Rich Bayless on Sep 1, 2009 11:14 AM

Inlet Pressure 100 psi

Outlet Pressure 14.7 psi

I will get you some pic's soon

SW2009 sp4.0

Attachments

Pressure Cut Plot.doc93.5 KB

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Loic Ancian @ 1-LSB132 on Sep 2, 2009 6:14 AM

Hi,

Maybe there is some cavitation??

If you check "cavitation" option you should not get negative values any more and see if cavitation area is important or not.

Actions

1-LSB132 @ Loic Ancian on Sep 2, 2009 9:37 AM

Thanks,

that seems to have solve the problem.

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Joe Galliera

@ 1-LSB132 on Sep 2, 2009 12:58 PM

There have been some performance inprovements in Flow Simulation 2010 when solving with cavitiation enabled.

Another question for you is whether you are treating this as an external flow problem or internal? If you have jetting out the sides, it may be helpful to run this as an internal flow by adding some dummy geometry surrounding the jet.

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7 Replies

Rich Bayless Aug 31, 2009 3:03 PM
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Correct Answer
Hello James,

What happens if you set a flow rate (mass or volume) on the inlet, along with a pressure at the outlet?

Cheers, Rich.
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- 1-LSB132 @ Rich Bayless on Aug 31, 2009 3:50 PM
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  Correct Answer
  Rich,
  
  We are not sure of the flowrate at the inlet because it is a new design. We have made some assumptions and guessed the flowrate based on older valve data, and it does work, but the flowrate is still in question because on 2 other sizes of valves the flowrate has increased and decreased based on the changes we have made and that changes the way we look at the dimensional changes made.
  
  Thanks James
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  - Rich Bayless @ 1-LSB132 on Sep 1, 2009 9:34 AM
    Mark Correct
    Correct Answer
    Hello James,
    
    can you post more details, such as the actual pressures you are applying at inlet and outlet?
    
    Also, post screenshots of your computational domain, and perhaps a cut plot or three? Trajectories perhaps?
    
    Also include your version, such as SW2009 SP2.1, or whatever.
    
    Thanks, Rich.
    Like • Show 0 Likes0
    Actions
    - 1-LSB132 @ Rich Bayless on Sep 1, 2009 11:14 AM
      Mark Correct
      Correct Answer
      Inlet Pressure 100 psi
      
      Outlet Pressure 14.7 psi
      
      I will get you some pic's soon
      
      SW2009 sp4.0
      Attachments
      Pressure Cut Plot.doc93.5 KB
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      Actions
      - Loic Ancian @ 1-LSB132 on Sep 2, 2009 6:14 AM
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        Correct Answer
        Hi,
        Maybe there is some cavitation??
        
        If you check "cavitation" option you should not get negative values any more and see if cavitation area is important or not.
        Like • Show 0 Likes0
        Actions
        1-LSB132 @ Loic Ancian on Sep 2, 2009 9:37 AM
        Mark Correct
        Correct Answer
        Thanks,
        
        that seems to have solve the problem.
        Like • Show 0 Likes0
        Actions
        Joe Galliera @ 1-LSB132 on Sep 2, 2009 12:58 PM
        Mark Correct
        Correct Answer
        There have been some performance inprovements in Flow Simulation 2010 when solving with cavitiation enabled.
        
        Another question for you is whether you are treating this as an external flow problem or internal? If you have jetting out the sides, it may be helpful to run this as an internal flow by adding some dummy geometry surrounding the jet.
        Like • Show 0 Likes0
        Actions

Water Flow through a jet

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