7 Replies Latest reply on Sep 2, 2009 12:58 PM by Joe Galliera

Water Flow through a jet

1-LSB132 Aug 31, 2009 12:45 PM

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.

Example.PDF 22.3 KB

Re: Water Flow through a jet

Rich Bayless Aug 31, 2009 3:03 PM (in response to 1-LSB132)

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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- Re: Water Flow through a jet
  
  1-LSB132 Aug 31, 2009 3:50 PM (in response to Rich Bayless)
  
  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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  - Re: Water Flow through a jet
    
    Rich Bayless Sep 1, 2009 9:34 AM (in response to 1-LSB132)
    
    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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    - Re: Water Flow through a jet
      
      1-LSB132 Sep 1, 2009 11:14 AM (in response to Rich Bayless)
      
      Inlet Pressure 100 psi
      
      Outlet Pressure 14.7 psi
      
      I will get you some pic's soon
      
      SW2009 sp4.0
      
      Pressure Cut Plot.doc 93.5 KB
      
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      - Re: Water Flow through a jet
        
        Loic Ancian Sep 2, 2009 6:14 AM (in response to 1-LSB132)
        
        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.
        
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        Re: Water Flow through a jet
        
        1-LSB132 Sep 2, 2009 9:37 AM (in response to Loic Ancian)
        
        Thanks,
        
        that seems to have solve the problem.
        
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        Re: Water Flow through a jet
        
        Joe Galliera Sep 2, 2009 12:58 PM (in response to 1-LSB132)
        
        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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