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    Statistical Validation of Surfaced Submarine Seakeeping Simulations Based on Open Water Tests
    (American Society of Mechanical Engineers (ASME), 2024-06)
    Büsken, Wiebke
    ;
    Krüger, Stefan
    Submarines are frequently required to operate in surfaced condition, partially in harsh seaways. Since diving is not always possible or permitted, an accurate prediction of a submarine’s seakeeping performance at the surface becomes essential for safe operation. The seakeeping of a surfaced submarine is a complicated problem of motions in all six degrees of freedom, which strongly depends on the respective parameter combination of seaway, forward speed, encounter angle, and surface stability. In this paper, time-domain seakeeping simulations are performed for a modern submarine hull form in short-crested irregular waves using the potential flow theory-based computation method E4-ROLLS. The simulation results of the roll, pitch and heave motions are compared with data obtained from open water model tests. These model tests were recently performed on a bay in Germany using free-running submarine models and specifically focused on the surface stability’s influence on the seakeeping in natural seaways. The presented research contributed to the development of a novel surface stability regulation DMS 1030-2 for submarines of the German Navy.
    Publicationtype: Conference Paper
      52
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    Seakeeping simulation of surfaced submarines and statistical validation based on model tests in open waters as part of the development of the new stability regulation DMS 1030-2 for the German navy
    (Taylor & Francis, 2024-05-07)
    Büsken, Wiebke
    This paper explains the need for the new surface stability regulation recently developed for the submarines of the German Navy and gives an overview of its general setup and main principles. Further, the test setup and main findings of open water model tests using two submarine hull forms on Eckernförde Bay are presented, which contributed towards the development of the new standard. Building on this introduction of the model tests, the results of an exemplary test run at specific combination of speed, stability, sea state and encounter angle are compared via statistical analysis with seakeeping simulation results using E4-ROLLS, a potential flow theory-based computation method. The comparison aims to check the suitability of E4-ROLLS for analyzing stability-dependent large-amplitude roll motions of surfaced submarines in natural seaways. The quality of results is discussed, whereby limitations of the simulation method are pointed out and the relevance of the presented research becomes apparent.
    Publicationtype: Journal Article
      15  23
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    Evaluation of seakeeping model tests in open waters using two submarine hull forms
    (American Society of Mechanical Engineers (ASME), 2023-06)
    Büsken, Wiebke
    ;
    Krüger, Stefan
    In this paper, the experimental procedure of seakeeping model tests in open waters with two free-running, remotely-controlled submarine hull forms as realized on Eckernförde Bay from October 2021 to April 2022 is presented. The objective of performing such model tests with surfaced submarines at various conditions of stability, speeds and encounter angles in natural seaway is explained. A summary of the qualitative observations concerning the different identified phenomena, which lead to large motion amplitudes, is given in this paper along with a quantitative evaluation of the model tests by statistical analysis of selected test runs. As part of the results, different heeling moments, which were observed to attack the surfaced submarine during these model tests, are discussed, especially in regard to their inclusion in the recently developed new stability standard for the intact surface stability of submarines of the German Navy.
    Publicationtype: Conference Paper
      17
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    Validation of time domain seakeeping computations based on capsizing model tests in natural seaways
    (American Society of Mechanical Engineers (ASME), 2022-06)
    Büsken, Wiebke
    ;
    Krüger, Stefan
    ;
    Russell, Philipp
    ;
    Frühling, Christian
    This paper presents further validation of the numerical computation method E4ROLLS, a nonlinear potential flow theory based seakeeping code, which is especially suitable for the early design stage due to its fast and efficient computation. The validation is achieved by comparison of simulation results with historical capsizing model test results of free-running self-propelled ship models in natural seaways. The results show that E4ROLLS is well-suited to assess the ships’ capsizing vulnerability, especially in following seas. Analysis of the historical tests’ video footage shows that the models’ capsizing in head seas was mainly induced by gusty wind. E4ROLLS is extended to include heeling moments caused by changing wind speeds and directions, so that wind-induced capsizing behavior can also be anticipated. The presented work highlights the benefits of model-scale seakeeping tests in natural seaways and shows that it is possible to assess the seakeeping of ships with fast and reliable methods in the early design stage.
    Publicationtype: Conference Paper
      69
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    Combination of time-domain flooding and evacuation simulations
    (2019-11)
    Römhild, Wiebke
    ;
    Krüger, Stefan
    This thesis aims to take further steps towards closing the gap between time-domain flooding and evacuation simulations. Time-Domain flooding simulations are a powerful tool to calculate the spread of floodwater throughout the vessel in damaged ship condition and provide useful insights into the flooding process and its influence on a ship`s stability. The ship`s motions are usually recorded as time logs of trim and heel. These motions shall serve as input to time-domain evacuation simulations of the same vessel in this project. Thus the author aims to gain a better understanding of evacuation as calculated under more realistic conditions than the current procedure of night and day cases in calm water intact conditions. The software used to perform the simulations is: NAPA for flooding and AENEAS for evacuation. Research is performed on a cruise vessel that was also part of the recent joint industry project eSAFE.
    Publicationtype: Master Thesis
      66
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    Untersuchung zur dynamischen Querflutungsberechnung im Zeitbereich
    (2019-03)
    Römhild, Wiebke
    In dieser Arbeit wird Querflutung im Zeitbereich für ausgewählte Beschädigungsfälle gerechnet, um zu überprüfen, ob ein Schiff mit Querflutungseinrichtungen in bestimmten Leckfällen mittels Querflutung noch die Endschwimmlage erreichen kann. Dazu wird ein von der Flensburger Schiffbau Gesellschaft (FSG) zur Verfügung gestellter Schiffsentwurf mit Hilfe ausgewählter Methoden der offenen Entwurfsmethoden Datenbank E4 untersucht. Es handelt sich dabei um den RoRo-Fahrgastschiffentwurf namens EMSA II. Dabei wird die Leckrechnung für dieses Schiff mit einer Monte-Carlo-Methode durchgeführt. Diese Methode erlaubt es, die Auswirkungen expliziter Leckgrößen anstelle der reinen Betrachtung von Flutungslängen aufgrund der Aufteilung zu untersuchen. Auf Basis der Untersuchungsergebnisse werden Annahmen getroffen, um Kriterien zur Gruppierung der Leckquader zu finden. Dabei wird auch der mögliche Nutzen dieser Betrachtung, insbesondere der dadurch erreichbare Überlebenswahrscheinlichkeitsgewinn in der probabilistischen Leckrechnung diskutiert. Schließlich werden die im Rahmen dieser Arbeit identifizierten Herausforderungen beim Umgang mit den verwendeten Methoden im Hinblick auf eine mögliche Automatisierung der Untersuchung zwecks Integration in die Entwurfsmethoden Datenbank erläutert.
    Publicationtype: Working Paper
      66
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      53