Increasing the Efficiency of a hydrofoil dagger board *HELP*

Discussion in 'Hydrodynamics and Aerodynamics' started by ross whitaker, Feb 16, 2018.

  1. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell "Whatever..."

    RW, I sent you a personal message (PM).
    Look under your profile...
     
  2. ross whitaker
    Joined: Feb 2018
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    Location: swansea

    ross whitaker Junior Member

    hi thank you both, tomorrow I will have a read through the session.txt file and see how I can get on, thank you for your help
     
  3. tspeer
    Joined: Feb 2002
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    Location: Port Gamble, Washington, USA

    tspeer Senior Member

    That's a good tip!

    What I was talking about was having the coordinates at the same X locations, something I've had to do manually on occasion.
     
  4. ross whitaker
    Joined: Feb 2018
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    Location: swansea

    ross whitaker Junior Member

    Hi sorry i have not replied i have been off ill for a while, i have given changing the coordinates into a .txt file a go with the e 818 when trying to load this .txt coordinate file into x foil the software crashed and closes every time. Do you know of a reason why this would be? I have attached the file to this post, many thanks, Ross
     

    Attached Files:

  5. ross whitaker
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    Location: swansea

    ross whitaker Junior Member

    I have just tried the same method with the e838 profile and it has since done the same and crashed and closed XFOIL
     

    Attached Files:

  6. tspeer
    Joined: Feb 2002
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    Location: Port Gamble, Washington, USA

    tspeer Senior Member

    Tabs. Thou shalt not use tab characters in an XFOIL input file.
     
  7. ross whitaker
    Joined: Feb 2018
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    Location: swansea

    ross whitaker Junior Member

    Thank you i have just tired this and taken the tabs out and the foil produced is now this ? and has not produced the desired profile?
     

    Attached Files:

  8. tspeer
    Joined: Feb 2002
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    Location: Port Gamble, Washington, USA

    tspeer Senior Member

    That shape is what your coordinates say it is. Here's a better set of coordinates.
     

    Attached Files:

  9. ross whitaker
    Joined: Feb 2018
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    Location: swansea

    ross whitaker Junior Member

    Hi i managed to make a similar file too and both of them are now working thank you, im going to try and do the same for the other three profiles now, i need to then run the simulations and compare the Cl nd Cd to find out which profile i will be taking forward into the final 3D design in solidworks
     

    Attached Files:

  10. ross whitaker
    Joined: Feb 2018
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    Location: swansea

    ross whitaker Junior Member

    hi i have managed to make the e838 work now, thank you i will post the documents up incase anyone else would like to use them, i will now try and convert the others and run simulations, thanks, Ross
     

    Attached Files:

  11. ross whitaker
    Joined: Feb 2018
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    Location: swansea

    ross whitaker Junior Member

    I was wondering if you knew there way a way to compare the L/D coefficients of each foil simultaneously or shall i just take the data from XFOIL and relay this information graphically using excel ? as I am looking at which profile is best to take forward into the 3D design ?
     
  12. ross whitaker
    Joined: Feb 2018
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    Location: swansea

    ross whitaker Junior Member

    whilst i have run the XFOIL simulations i have increased the iterations of the simulation to get rid of the NOT CONVERGING but this is still here do you know why this is ? many thanks, Ross
     

    Attached Files:

  13. ross whitaker
    Joined: Feb 2018
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    Location: swansea

    ross whitaker Junior Member

    I have been trying to do a range on each of the foils to gather their Cl, Cd L/D ratio but on each foil there are always converging errors, do you know why this is as this is really halting my design as i need to get blades 3D printed next week ? many thanks Ross
     

    Attached Files:

  14. Erwan
    Joined: Oct 2005
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    Erwan Senior Member

    You should try with alpha<6° instead of 15°

    Cl=8.0 seems a bit unrealistic

    I am not surprised it doesn t converge
     

  15. ross whitaker
    Joined: Feb 2018
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    Location: swansea

    ross whitaker Junior Member

    Thank you Erwan, Does anyone know of any software to measure the cavitation please?
     
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