Impact of Forced Roll Motion on the Ice Resistance of Modern Icebreaking Bow Geometries

2021 ◽  
Author(s):  
Johanna Marie Daniel ◽  
Tuomas Romu ◽  
Franz Von Bock Und Polach ◽  
Moustafa Abdel-Maksoud ◽  
Toni Skogstr\xf6m
Keyword(s):  
Roll Motion ◽  
Forced Roll ◽  
Ice Resistance

Impact of Forced Roll Motion on the Ice Resistance of Modern Icebreaking Bow Geometries

2020 ◽  
Author(s):  
Johanna Marie Daniel ◽  
Tuomas Romu ◽  
R. U. Franz von Bock und Polach ◽  
Moustafa Abdel-Maksoud ◽  
Toni Skogström
Keyword(s):  
Model Tests ◽  
Roll Motion ◽  
Power Demand ◽  
Hull Form ◽  
Forced Roll ◽  
Ice Conditions ◽  
Level Ice ◽  
Metacentric Height ◽  
The Impact ◽  
Ice Resistance

Abstract Following the development of low friction hull coatings and azimuthing propulsion for icebreaking vessels, the development of auxiliary systems for reducing ice resistance fell from focus of research. One of these systems is comprised of active heeling tanks which induce a forced roll motion on the icebreaker. Today it is not fully understood how effective or even useful such systems would be for the icebreaking performance in combination with a modern icebreaking hull form. In this study, the impact of active heeling systems on level ice resistance is investigated by performing ice model tests with an icebreaker representing the latest design generation. The level ice thickness used in the model tests corresponds to the maximum continuous icebreaking capability of the evaluated vessel in multi-year ice conditions. Additionally, a calculation method is developed to predict the impact of forced roll motion on the ice resistance. The calculated prediction is evaluated against the model-scale data. Finally, the effectiveness of the active heeling system is evaluated from an engineering perspective: does the active heeling system reduce the power demand, or would the same result be achievable by increasing the propulsion power accordingly. It was found that the roll motion impacts the ice resistance in level ice. The main influence in this regard lies with the tank volume and metacentric height of the icebreaker. Additionally, it was observed that an optimum heel angle dependent on the ice condition can be determined which is not necessarily the highest one achievable. The case study predicts a reduced power demand for a modern icebreaker hull form in harsh ice conditions.

Numerical Methods for the Prediction of the Bilge Keel Effects on the Response of Ship-Shaped Hulls

2007 ◽  
Author(s):  
Spyros A. Kinnas ◽  
Yi-Hsiang Yu ◽  
Vimal Vinayan
Keyword(s):  
Numerical Scheme ◽  
Hydrodynamic Interaction ◽  
Roll Motion ◽  
Length Scale ◽  
Hull Form ◽  
Longitudinal Length ◽  
Forced Roll ◽  
Hull Forms ◽  
Volume Method ◽  
Bilge Keel

This paper addresses the hydrodynamic interaction and response of typical FPSO/FSO and LNG hull-forms with bilge keels. The hull-forms are assumed to be slender with the longitudinal length-scale exceeding the other two physical dimensions. This assumption allows the modeling of the flow around the hull-form in a 2-D strip-wise manner. A Finite Volume Method (FVM) based numerical model is developed to analyze the flow around the 2-D hull-sections, with and without bilge keels. The effect of the bilge keels in the damping of hull motions is presented with the application of the numerical scheme to a hull in forced roll motion, and its transient response in roll and heave decay.

Parametric Identification of Nonlinear Ship Roll Motion from Forced Roll Data

1988 ◽  
Vol 32 (02) ◽  
pp. 101-111 ◽  
Author(s):  
P. J. Gawthrop ◽  
A. Kountzeris ◽  
J. B. Roberts
Keyword(s):  
Simulated Data ◽  
Real Data ◽  
Estimation Procedure ◽  
Parametric Identification ◽  
Efficient Estimation ◽  
General Nature ◽  
Roll Motion ◽  
Forced Roll ◽  
Ship Roll ◽  
Ship Roll Motion

A method of estimating the parameters in a nonlinear, single-degree-of-freedom model of ship roll motion is described. It is shown that the "linear-in-the-parameters" nature of the model allows formulation of a relatively simple, and computationally very efficient, estimation procedure, based on a recursive, linear least-squares algorithm. The method is applied to the case of forced roll, where the roll moment excitation can be accurately determined. The general nature of the estimation scheme allows the combining of data from a sequence of experiments with sinusoidal forcing of varying frequency, and also allows the use of data arising from a nonsinusoidal forcing moment. In the latter case all the required parameters in the ship motion model can be estimated from a single test. The technique is illustrated by applying it to both digitally simulated data (where the parameters are known, a priori) and to real data, obtained from a model ship. In the latter case the parameter values obtained by the proposed method are shown to agree well with estimates obtained by alternative, independent methods.

scholarly journals An Approach to Determine Optimal Bow Configuration of Polar Ships under Combined Ice and Calm-Water Conditions

2021 ◽  
Vol 9 (6) ◽  
pp. 680
Author(s):  
Hui Li ◽  
Yan Feng ◽  
Muk Chen Ong ◽  
Xin Zhao ◽  
Li Zhou
Keyword(s):  
Numerical Simulation ◽  
Water Resistance ◽  
Numerical Technique ◽  
Experimental Studies ◽  
Resistance Index ◽  
Simulation Method ◽  
Present Approach ◽  
Calm Water ◽  
Level Ice ◽  
Ice Resistance

Selecting an optimal bow configuration is critical to the preliminary design of polar ships. This paper proposes an approach to determine the optimal bow of polar ships based on present numerical simulation and available published experimental studies. Unlike conventional methods, the present approach integrates both ice resistance and calm-water resistance with the navigating time. A numerical simulation method of an icebreaking vessel going straight ahead in level ice is developed using SPH (smoothed particle hydrodynamics) numerical technique of LS-DYNA. The present numerical results for the ice resistance in level ice are in satisfactory agreement with the available published experimental data. The bow configurations with superior icebreaking capability are obtained by analyzing the sensitivities due to the buttock angle γ, the frame angle β and the waterline angle α. The calm-water resistance is calculated using FVM (finite volume method). Finally, an overall resistance index devised from the ship resistance in ice/water weighted by their corresponding weighted navigation time is proposed. The present approach can be used for evaluating the integrated resistance performance of the polar ships operating in both a water route and ice route.

scholarly journals Formulation of Ice Resistance in Level Ice Using Double-Plates Superposition

2020 ◽  
Vol 8 (11) ◽  
pp. 870
Author(s):  
Liang Li ◽  
Qingfei Gao ◽  
Alexander Bekker ◽  
Hongzhe Dai
Keyword(s):  
Elastic Plate ◽  
Approximate Model ◽  
Ice Thickness ◽  
Full Scale Test ◽  
Ship Resistance ◽  
Bending Resistance ◽  
Level Ice ◽  
Scale Test ◽  
Coulomb Criterion ◽  
Ice Resistance

The estimation of ship resistance in ice is a fundamental area of research and poses a substantial challenge for the design and safe use of ships in ice-covered waters. In order to estimate the ice resistance with greater reliability, we develop in this paper an improved Lindqvist formulation for the estimation of bending resistance in level ice based on the superposition of double-plates. In the developed method, an approximate model of an ice sheet is firstly presented by idealizing ice sheeta as the combination of a semi-infinite elastic plate and an infinite one resting on an elastic foundation. The Mohr–Coulomb criterion is then introduced to determine the ice sheet’s failure. Finally, an improved Lindqvist formulation for estimation of ice resistance is proposed. The accuracy of the developed formulation is validated using full-scale test data of the ship KV Svalbard in Norway, testing the model as well as the numerical method. The effect of ice thickness, stem angle and breadth of bow on ship resistance is further investigated by means of the developed formulation.

Detection of Vehicle Tripped and Untripped Rollovers by a Novel Index With Mass-Center-Position Estimations

2017 ◽  
Author(s):  
Fengchen Wang ◽  
Yan Chen
Keyword(s):  
Load Transfer ◽  
Center Of Mass ◽  
Roll Motion ◽  
Mass Center ◽  
Motion Models ◽  
Center Position ◽  
Before And After ◽  
Vehicle Rollover ◽  
Lift Off ◽  
Rollover Index

This paper presents a novel mass-center-position (MCP) metric for vehicle rollover propensity detection. MCP is first determined by estimating the positions of the center of mass of one sprung mass and two unsprung masses with two switchable roll motion models, before and after tire lift-off. The roll motion information without saturation can then be provided through MCP continuously. Moreover, to detect completed rollover statues for both tripped and untripped rollovers, the criteria are derived from d’Alembert principle and moment balance conditions based on MCP. In addition to tire lift-off, three new rollover statues, rollover threshold, rollover occurrence, and vehicle jumping into air can be all identified by the proposed criteria. Compared with an existing rollover index, lateral load transfer ratio, the fishhook maneuver simulation results in CarSim® for an E-class SUV show that MCP metric can successfully predict the vehicle impending rollover without saturation for untripped rollovers. Tripped rollovers caused by a triangle road bump are also successfully detected in the simulation. Thus, MCP metric can be successfully applied for rollover propensity prediction.

Vehicle’s New Anti-Roll System for Suspension Parasitic Stiffness Reduction and Non-Linear Roll Stiffness Characteristic

2013 ◽  
Author(s):  
Bo Min Kim ◽  
Dae Sik Ko ◽  
Jong Min Kim
Keyword(s):  
Ride Comfort ◽  
Torsional Stiffness ◽  
Operating Efficiency ◽  
Leaf Spring ◽  
Roll Motion ◽  
Stiffness Reduction ◽  
Stiffness Characteristic ◽  
Non Linear ◽  
Roll System ◽  
Vehicle Dynamic Simulation

In general, vehicle uses torsional stiffness of a stabilizer bar to control the roll motion. But this stabilizer bar system has problems with degradation for ride comfort and vehicle’s NVH characteristic due to the suspension parasitic stiffness caused by deformation and wear of the stabilizer bar rubber bush. In addition, it is difficult to control the vehicle’s roll motion effectively in case of excessive vehicle roll behavior when it is designed to satisfy ride comfort simultaneously because of the stabilizer bar’s linear roll stiffness characteristic. In this paper, the new anti-roll system is suggested which consists of connecting link, push rod, laminated leaf spring, and rotational bearing. This new concept anti-roll system can minimize the suspension parasitic stiffness by using rotational bearing structure and give the vehicle non-linear roll stiffness by using the laminated leaf spring structure which are composed of main spring and auxiliary one. Reduction of suspension parasitic stiffness and realization of non-linear roll stiffness in this anti-roll system were verified with both vehicle dynamic simulation and vehicle test. Also, this study includes improvement of the system operating efficiency through material change and shape optimization of the leaf spring, and optimal configuration of the force transfer system.

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