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Numerical simulation of ship motion under consideration of design criterion for dynamic-positioning-systems
Citation Link: https://doi.org/10.15480/882.13435
Publikationstyp
Doctoral Thesis
Date Issued
2024
Sprache
English
Author(s)
Advisor
Referee
Title Granting Institution
Technische Universität Hamburg
Place of Title Granting Institution
Hamburg
Examination Date
2024-04-17
Institute
TORE-DOI
First published in
Number in series
731
Citation
Schriftenreihe Schiffbau 731: (2024)
ISBN
978-3-89220-731-3
The present thesis is concerned with the development and application of a simulation plattform called ”DPTool” for evaluating the Dynamic-Positioning (DP) capability of typical DP vessels with Voith-Schneider propellers in the time domain. The platform takes into account realistic environmental loads such as wind, waves, and currents, which have been investigated both numerically and experimentally. The numerical methods include simulating ship motion in waves, parameterizing control using system identification, and an allocation module for de termining control inputs to maneuvering devices. These methods are integrated into a holistic MATLAB/Simulink model as a ”Software-in-the-Loop” (SIL) and can be operated through a graphical interface.
Ship motion is simulated using the ”IMPRES” method based on impulse response functions in potential theory. The DP system control is achieved through a nonlinear PID controller with a Kalman filter for ship motion in waves. An optimization algorithm is used for the allocation module to generate the required maneuvering forces realistically and efficiently within a short time.
In the scope of this work, wind, current, and wave forces on two models, an offshore supply vessel and a tugboat, have been investigated and measured through experiments. Wind force measurements were conducted in the wind tunnel of the Hamburg University of Technology. The influence of the wind tunnel’s boundary layer was examined prior to the measurements.
Flow forces were measured in the towing tank of SVA-Potsdam. For this purpose, the offshore supply vessel model was towed through the tank at various encounter angles and speeds using a force measurement carriage. A comparison of the evaluated experiments with three different numerical methods - a steady-state and a transient Reynolds-Averaged Navier-Stokes (RANS) simulation, as well as a hybrid Detached Eddy Simulation (DES) approach - quantifies the discrepancies between the various methods and the experiments. Determination of wave forces was achieved by restraining the model with springs, allowing for full first-order motion. The measurements were compared with three different numerical methods: a two-dimensional strip method PDStrip, a three-dimensional panel method in the frequency domain, and a transient RANS method.
The impacts of deviations between experimental and numerically simulated forces on DP simulations are presented in the work through comparative simulations. The functionalities of the ”DPTool” are demonstrated in a use case, comparing a static method with the dynamic method developed in this work in the time domain.
Ship motion is simulated using the ”IMPRES” method based on impulse response functions in potential theory. The DP system control is achieved through a nonlinear PID controller with a Kalman filter for ship motion in waves. An optimization algorithm is used for the allocation module to generate the required maneuvering forces realistically and efficiently within a short time.
In the scope of this work, wind, current, and wave forces on two models, an offshore supply vessel and a tugboat, have been investigated and measured through experiments. Wind force measurements were conducted in the wind tunnel of the Hamburg University of Technology. The influence of the wind tunnel’s boundary layer was examined prior to the measurements.
Flow forces were measured in the towing tank of SVA-Potsdam. For this purpose, the offshore supply vessel model was towed through the tank at various encounter angles and speeds using a force measurement carriage. A comparison of the evaluated experiments with three different numerical methods - a steady-state and a transient Reynolds-Averaged Navier-Stokes (RANS) simulation, as well as a hybrid Detached Eddy Simulation (DES) approach - quantifies the discrepancies between the various methods and the experiments. Determination of wave forces was achieved by restraining the model with springs, allowing for full first-order motion. The measurements were compared with three different numerical methods: a two-dimensional strip method PDStrip, a three-dimensional panel method in the frequency domain, and a transient RANS method.
The impacts of deviations between experimental and numerically simulated forces on DP simulations are presented in the work through comparative simulations. The functionalities of the ”DPTool” are demonstrated in a use case, comparing a static method with the dynamic method developed in this work in the time domain.
Subjects
Dynamic-Positioning
Impulse-Response-Function
Simulation of Dynamic Capability
Simulation of Ship Motion
Voith-Schneider-Propeller
DDC Class
623: Military Engineering and Marine Engineering
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