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Simulation of Submarine Manoeuvring
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Naval Systems.
2015 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The best way to save money in a submarine design project is to, in an as early stage as possible, be able to find errors in a design or construction. A powerful method to find such errors is to put the design through rigorous testing in simulation software. This project has created a simulation program for a submarines cruising fully submerged. The software is using well-known and established equations of motion (EOM’s) that has been developed through the years. These equations describe the forces and moments acting on the submarine in six degrees of freedom and can be described with Newton’s second law of motion. The equations accelerations are integrated using the scipy.integrate.odeint module in Python to obtain the translational and rotational velocities for a time series. By integrating the EOM’s with different initial values and conditions a library of standard manoeuvring tests have been created together with graphically tailored representation for each test result. The software has been verified by comparing a few chosen test results with simulation software currently used by FOI. Through this comparison it is seen that the software correlates well with the current one in every aspect except one. There is an uncorrelated phenomenon when stern-plane diving is simulated. The error is identified to the stern-plane drag term in the surge equation, Xδsδs . Evidence shows that an error might exist in the current software and a dialogue with the manufacturer has been commenced. Until the error is solved, results from tests using stern-plane diving motions should be handled with care.

Abstract [sv]

Simulering av ub˚atsman¨ovreringDet b¨asta s¨attet att spara pengar inom ett ub˚atdesignprojekt ¨ar att, i ett s˚a tidigt skede som m¨ojligt, hitta fel i designen. En kraftfull metod att hitta s˚adana fel ¨ar att f¨ora designen genom rigor¨osa tester i ett simulering program. Detta projekt har skapat ett s˚adant program f¨or en ub˚at som r¨or sig i undervattensl¨age. Pro-grammet anv¨ander sig av v¨alk¨anda och etablerade r¨orelseekvationer som har utvecklats genom ˚aren. Dessa ekvationer beskriver krafter och moment som ¨ar verksamma p˚a en ub˚at i sex frihetsgrader som kan beskrivas med Newton’s andra r¨orelselag. Ekvationernas accelerationer integreras med hj¨alp av scipy.integrate.odeint modulen i Python f¨or att erh˚alla ub˚atens translation- och rotations-hastigheter f¨or en tidsserie. Genom att integrera r¨orelseekvationerna med olika begynnelsev¨arden och villkor s˚a har ett bibliotek av man¨ovrering-stester blivit framtaget tillsammans med anpassad grafisk representation av testresultaten. Programmet har verifierats genom j¨amf¨orelse av n˚agra valda test gentemot programmet som i dagsl¨aget anv¨ands av FOI. Denna j¨amf¨orelse har visat att programmen korrelerar bra i alla fall utom ett. Vid dykning genom att anv¨anda aktra djuproder s˚a korrelerar inte programmen gentemot varandra. Felet har blivit identifierat till dragmotst˚andet som uppst˚ar p˚a rodren i x-ekvationen, Xδsδs . Det ¨ar inte otroligt att felet kan ligga i programmet som anv¨ands i dagsl¨aget och en dialog med skaparna har initierats. Tills detta problem ¨ar utrett b¨or man vara medveten om att resultat fr˚an simuleringar d¨ar aktra djuproder anv¨ands kan ha l¨agre precision.

Place, publisher, year, edition, pages
2015. , 86 p.
TRITA-AVE, ISSN 1651-7660 ; 2015:66
National Category
Engineering and Technology
URN: urn:nbn:se:kth:diva-185028OAI: diva2:917991
Available from: 2016-04-12 Created: 2016-04-08 Last updated: 2016-04-12Bibliographically approved

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