Acoustic Analysis of Submarines

Discussion in 'Boat Design' started by issac82, Mar 10, 2008.

  1. issac82
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    issac82 Junior Member

    Hi,
    I am new in this forum and I hav gone through many threads but the members are not discussing much about the acoustic signature which is getting growing attention of the researchers now a days. One thing I want to ask that I want to do the acoustic analysis of submarine. Can somebody guide me in this regard that what I have to do and How I can do all this??thanx in anticiapation
     
  2. Leo Lazauskas
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    Leo Lazauskas Senior Member

    We don't discuss it much because it is not an issue most of the boaties here face on a daily basis.

    I can suggest a few causes of acoustic noise that might help your search, e.g the noise of internal machinery and the vibration of the hull, and fluid effects such as boundary layer separation.

    Here's something to ponder on...
    Can sound be generated without producing vortices?
    If not, what frequencies are generated by, say, ring vortices in a fluid?

    These are deep issues and the mathematics is pretty difficult. Are you really nerdy enough for that?

    All the best,
    Leo.
     
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  3. tom28571
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    tom28571 Senior Member

    For information available to the public on the net, Google SOSUS network or Caesar submarine network. I worked on these systems under the deep ocean way back yonder. Signatures were defined by spectral analysis and bearing to vessel by time intercept of individual hydrophones in a very long array. The array was electronically steered, much like modern phased array RADAR systems.

    Individual classes of vessels have distinct signatures and even particular vessels may have distinct signatures depending on the equipment running and especially the number and kind of propellers.

    Trying to get very far into this area will run you into deep secret, and unavailable material. I recommend a book titled "Blind Man's Bluff" for some historical material of cold war submarine warfare.
     
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  4. issac82
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    issac82 Junior Member

    I feel the acoustic analysis si getting a lot of attention off he researhers now a days and becoming aan improtant field these days.specially the analysis of underwater vessels.I think much researh is in progress but here i have nobody seems interted in this field??
     
  5. Leo Lazauskas
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    Leo Lazauskas Senior Member

    There is some interest (by me) but probably few others on
    boatdesign.net.

    There is also a bit that might help you at the Australian
    Defence Science and Technology Organisation (DSTO) web site:

    http://www.dsto.defence.gov.au/publications/scientific.php

    Enter "Acoustic signature" into the Search Box.
    About 50 publications are listed.

    People I know have had recent contact with personnel at the
    Chinese Scientific Ship Research Center (CSSRC) to discuss
    submarine-related matters.

    You could try contacting people at CSSRC in Wuxi (near
    Shanghai). Try, for example, Dr. Zhang Jun, Prof. Zhang Xiaoci,
    Dr. Gao Ji-Lin, Mr Yao Zhichong or Prof. Yan Kai and they might
    be able to help you further.

    Good luck,
    Leo.
     
  6. yipster
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    yipster designer

    why not, i add some thoughts also than, with the speed of sound in one ping only
    depth and fishfinders, 3d forward looking maps etc make acoustic analyses we all use
    shipscrews are known for acoustic resonances on the hull and many study's are made
    there's also an oceanic acoustic buoy relay system and submarines carry it to the limit
    water physics sure are interesting and many links on subs and acoustics in wiki alone
     
  7. issac82
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    issac82 Junior Member

    All these thinsg are right but from a naval structural designer and architect wht approach and things should be kept in mind while designing and which type of analysis should b done in this regard.
     
  8. Leo Lazauskas
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    Leo Lazauskas Senior Member

    Isaac82, we have already given you a lot of advice. We have suggested places to find papers, expert people in China to contact for help, books to read and mathematical approaches that might help your research. Have you tried any of these yet?

    I don't mean to be rude, but part of the problem is that your English is not very good and you might have trouble understanding some of the papers you will need to read. (I think that you are very brave to study in a new, difficult language!)

    If you are Chinese, you really should contact the submarine experts in Wuxi for help.

    Good luck,
    Leo.
     
  9. alan white
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    alan white Senior Member

    The acoustic signature is, I think, due to the reduction gearboxes that convert high rpm turbine speeds to very slow prop speeds.
    The problem is that normal spur gears have uneven output pitchline velocities due to the impossability of machining absolutely perfect gear teeth.
    Other drives may already be in use. They would be trochoidal drives, which use (sometimes) rollers following sinusoidal paths. These reduction drives have very low friction and extremely low noise.
    Because of cost, the drives are limited to things like submarines. They will spend millions on subs to reduce noise.
    I've seen the patent for a roller drive in the patent archives that the US navy purchased in the 1980s. It was identical to a design of my own. Someone got there ahead of me. Of course, what goes into nuclear subs is top secret.

    Alan
     
  10. Leo Lazauskas
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    Leo Lazauskas Senior Member

    Hi Alan,
    That's one type of noise source, i.e. mechanical. There also noises due to fluid effects, such as the separation of the boundary layer near the nose when the sub is at an angle of attack or if it is poorly designed, separation at the junction of the hull and the conning tower, and vortices shed from the props.

    Sub-hunting is a fascinating subject to be sure. Other particularly difficult "signatures" to hide are the internal waves made when there are fluid density differences (these waves can be hundreds of metres high!), and my favourite, bioluminescence.

    As you suggested, what nucular subs do to minimise these effects is anybody's guess.

    Regards,
    Leo.
     
    Last edited: Mar 12, 2008
  11. tspeer
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    tspeer Senior Member

    I was once asked by a prominent acoustician if I'd read the book, "Deep Lie" by Stuart Woods (I had) when the subject of signatures came up. It's fiction, but his demeanor indicated it was not necessarily all that fictional.
     
  12. Pericles
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    Pericles Senior Member

    Then you listen for what is not there because if the sound of the ocean has a hole, there's your sub. :D :D :D

    Pericles
     
  13. tom28571
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    tom28571 Senior Member

    Sounds like a great line for a movie or, maybe it has already been used. If the sub captain was smart and had the needed equipment to detect the acoustic "hole", it might even be true.

    Since I knew Stuart Woods early in his writing career even before he was a gourmet food critic for the Atlanta Constitution, I read all his early books. Later, he seemed to be too much influenced by Stephen King or similar writers and went off the deep end, so to speak, and I quit reading him. For me, his best books were the second one, "Chiefs" and a later "Palindrome". Most do not know of his first book (which is how I came to meet him) "Blue Water, Green Skipper" which is about sailing the Atlantic from East to West. Not a bad book, as cruising books go.
     
  14. Pericles
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    Pericles Senior Member


  15. tom28571
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    tom28571 Senior Member

    I have the dubious distinction of actually serving aboard a destroyer that attacked a submarine. It occurred while my Tin Can, USS Duncan DDR 874 was in the screen for Task Force 77, operating off North Korea in 1952. A sub was detected and any sub in the area of the task force was deemed an enemy sub. Duncan and another tin can were sent to take it out or, at least send the message that no sub would be tolerated near the task force. Both tin cans ran patterns of depth charges. Impressive above water and scary as hell if you happen to be the target underwater. The attack was suddenly called off and a helicopter ran a circuit picking up "guard mail". We peons never knew the outcome but the sub was undoubtedly Russian out of Vladivostok which was nearby to the north of us.

    At the time, we hoped that we had killed the SOB but, now I am much less inclined to kill anyone, especially peons serving some dictator or politician.

    At that time we ran active SONAR of the BQQ series.
     
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