LEE- Gemi İnşaatı ve Gemi Makinaları Mühendisliği-Yüksek Lisans

Bu koleksiyon için kalıcı URI

http://hdl.handle.net/11527/19283

Gözat

Yazar "Kınacı, Ömer Kemal" ile LEE- Gemi İnşaatı ve Gemi Makinaları Mühendisliği-Yüksek Lisans'a göz atma
  • Öge
    The sensitivity analysis of manoeuvring derivatives on a VLCC with turning circle simulation tests
    (Graduate School, 2024-07-10) Adnar, Suat ; Kınacı, Ömer Kemal ; 508181026 ; Naval Architecture and Marine Engineering
    A ship moving in six degrees of freedom (6DOF) exhibits surge, sway and yaw movements in calm water horizontally and these motions determine the manoeuvrability of the ship. Manoeuvrability can be defined as the ability of a vessel to manoeuvre to a desired course in a controlled manner and the effort required to maintain a given course. Although heave, pitch and roll motions are usually studied for seakeeping analysis, they can also be included in manoeuvring calculations. The International Maritime Organisation (IMO) requires ships to meet minimum manoeuvring performance criteria. In considering the service life of the ships, it is important to make predictions at the preliminary design stage with regard to manoeuvring performance, which is one of the most important performance criteria. In order to make these predictions, it is necessary to begin with the most efficient method in the triangle of cost, time and accuracy. System identification methods represent a particularly attractive methodology at this point. The system identification method can be defined as the construction of a mathematical model comprising both linear and non-linear components, based on experimental data and statistical methods. The accuracy of this method, which gives very quick results, is also relatively high. However, obtaining hydrodynamic coefficients can be defined as a disadvantage of this method. The hydrodynamic force and moment derivatives of the manoeuvre can be calculated by means of Computational Fluid Dynamics (CFD) simulations or experimental model tests. The hydrodynamic coefficients are obtained by nondimensionalising the hydrodynamic derivatives. A mathematical model can be constructed based on experimental and numerical data. Abkowitz and MMG models are the most widely accepted mathematical models in the academic literature. American Bureau of Shipping (ABS) has proposed a mathematical model based on MARAD systematic series experiment data. ABS recommends this model to its clients for use in the preliminary design stage. The impact of hydrodynamic derivatives on the manoeuvring characteristics of the mathematical model is a subject of ongoing research. One of these research methods to be carried out in various ways is sensitivity analysis. In sensitivity analysis, the effects of certain deviations of the hydrodynamic coefficients on the manoeuvring indices are investigated by mathematical models. This enables the creation of a simpler and new mathematical model by removing the coefficients whose effect degrees will be neglected from the equation. In the existing literature, there have been investigations into the application of sensitivity analyses to a number of different models, including Abkowitz and MMG mathematical models. However, there is no evidence of a sensitivity analysis having been conducted on the ABS model. The objective of this thesis was to perform numerical simulations using the ABS mathematical model which derived by system identification method and to carry out a sensitivity analysis. The effects of hydrodynamic coefficients are investigated by simulating the turning manoeuvre of a VLCC ship using numerical simulations. The coefficients with the highest and least impact on the turning manoeuvre are identified and presented. This study is analysed under four headings. Section 1 contains a literature review and basic information. Section 2 outlines the linear and non-linear equations of the mathematical model used in numerical simulations. Section 3 provides information on the numerical simulations and presents the simulation outputs. Finally, Section 4 summarises the results and offers an interpretation.