Software for submarine modelling

Discussion in 'Software' started by user_friendly, Aug 10, 2004.

  1. user_friendly
    Joined: Aug 2004
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    user_friendly New Member

    i wish to draw and then calculate the hydrostatic and drag values of some submarine shapes i have in mind. Would hull design programs such as autoship or prolines be suitable or do i need something more specific to submarines?

    thanks in advance,

    Matthew
     
  2. DaveB
    Joined: Dec 2003
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    DaveB Senior Member

    If they're streamlined and symmetrical about the longitudinal axis you might be able to use a potential flow code to estimate the drag on a 2-d section... I've heard good things about xfoil....

    I think you might find it to get pretty tangly... if you're just lookin' for rough numbers you could consult a fluids handbook for equations and estimate it from projected and surface areas. They tend to have a bunch of worked examples for common shapes like cylinders or ellipses...
     
  3. jehardiman
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    jehardiman Senior Member

    First, most of the good codes I know of are very proprietary and none work really well except in the small regime/problem they were written for. Additionally, once you get away from pure bodies of revolution in inviscid, irrotational fluids, everything falls apart real quickly for most CFD codes and many "behaviours" have to be faked in to agree with sea trials data.

    Give me a hint at what you're doing and I may be able to point you at some open source literature.
     
  4. sorenfdk
    Joined: Feb 2002
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    sorenfdk Yacht Designer

    Although Xfoil is a very good program, I doubt very much that it will be able to handle submarine-like shapes.

    Anyway, Xfoil is, as DaveB mentions, a 2-D code, and the flow around a submarine is of course 3-D, so the results will not be trustworthy.
     
  5. Leo Lazauskas
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    Leo Lazauskas Senior Member

    You can use Michlet to calculate the total (wave + viscous) drag. See:
    www.cyberiad.net/michlet.htm

    For some calculated wave patterns of a sub broaching, see:

    www.cyberiad.net/wakesub.htm

    I could recommend other codes I have or know about but it depends on what sort of detail you are after. For example, do you want to estimate boundary layer separation? How close to the surface is your sub likely to be? etc.

    All the best,
    Leo.
     
  6. emre

    emre Guest

    interest in sub design

    helo,
    I m also interested in submarine design (and I also work at submarine construction)
    can you pls contact me at : pressure_hull@hotmail.com

    bye
     
  7. burakreis
    Joined: Feb 2002
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    burakreis Junior Member

    in general any hull design software can model a submarine hull. although most of the general purpose cad software can also do the job easily, same for the hydrostatics.

    but for the drag it is not that easy. a modern sub hull is not axisymetric in real but the pressure hull. there are at least the outer deck structure, a sail, horizontal and vertical rudders etc so 2d modeling approach will not work. i guess michlet may predict the drag in an acceptable range of accuracy and may help to compare similar sub hull forms for pre-design.

    but for a viscous 3d simulation on a full sub hull with appandages you will need expensive software and hardware with parallel processing and also expertise and at the end, due to the complexity of the physics for this kind of flow you still may or may not get the picture at all :)

    regards,

    burakreis
     
  8. zeroname
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    zeroname Naval Architect

    ask the company..
     
  9. yachty4000
    Joined: Apr 2004
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    yachty4000 Junior Member

    I agree with "cargo steel" and I use to be able to use GRC Paramarine haven't played with it for about 4 years. It is quite specialist it origionally started of a MOD software before computers became mainstream in design and then they funded its development by making it commercially available it is very powerful and as the website above suggest it is designed to cope with submarine.

    Most naval architecture surface modeller can model a submarine very few would produce hydrostatics I would trust without checking as most didn't have submarine inmind when the developer did the programming. If there is funding have a look into paramarine.
     

  10. Guest625101138

    Guest625101138 Previous Member

    I have attached a paper that was originally posted by Tom Speer. It covers a range of laminar flow shapes that extends beyond the low Re# regime of the Carmichael Laminar Flow hull.

    These shapes get impressively low drag if you have conditions that will sustain laminar flow over the frontal portion. I expect you would need very good surface finish and steady trajectory to get near this. The data is for air so only applies to deep water operation of a submarine.

    Michlet gives good results for typical slender ellipsoid shape whether it is operating at depth or near surface. It is the only simple method to determine the wave drag accurately.

    JavaFoil allows you to analyse shapes in 2D. The results for the foils have relative comparison with the attached paper but the drag values cannot be directly correlated to the case involving a body of revolution of the section.

    I have attached some examples from JavaFoil to show you how the surface finish can impact on drag with these Laminar Flow shapes. You will see that with painted fabric the turbulent transition occurs much earlier on the foil than in the case of smooth finish. The drag is increased by over a factor of two as a result.

    I expect if you place X-sections of your hulls in JavaFoil, set the appropriate Re# and surface finish you will get close to the comparative performance of the various hulls.

    In dead calm conditions I notice a reduction in drag on surface boats but I need to operate very steadily. I do not know if anything other than a hull rising under its own buoyancy will actually achieve laminar flow.

    Maybe someone with some maths nouse will produce a little package for the panel method applied to a body of revolution.

    Rick W
     

    Attached Files:

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