Numerical Study on Fish Tail Shaped Rudder for Improved Ship Maneuvering

2015 ◽  
Author(s):  
Mannam Naga Praveen Babu ◽  
P. Krishnankutty
Keyword(s):  
Surface Area ◽  
Numerical Study ◽  
Control Force ◽  
Ship Maneuvering ◽  
Safety Regulations ◽  
Open Sea ◽  
Stream Condition ◽  
Ship Maneuverability ◽  
Force Moment ◽  
Turning Maneuver

Maneuvering is an important safety aspect in ship operations so as to avoid accident of ships in seaways and more critically in the restricted area of waterways. IMO stipulates many safety regulations on ship maneuverability in open sea conditions and the local authorities may have additional regulations in harbor, canal and other restricted waterways. The effectiveness of rudder has substantial influence on the maneuverability of a ship. It is often difficult to increase the size of the rudder, to get higher control force/moment, due to the geometrical restrictions of the aft aperture of the ship. A hydrodynamically efficient rudder section addresses this problem to some extent. Most of the fishes maneuver efficiently using their tail. The fish tail functions almost similar to that of a rudder for its movements and navigation. In general, ship with flap rudders and fish tail shaped rudders perform maneuverability better compare to a ship fitted with a conventional rudder having the same underwater surface area. In fishtail shaped rudders, the shape and movements promote good flow patterns in a wider range of rudder angles. In a fish tail, the trailing edge accelerates the flow and recovers lift over the aft section of the rudder. This results in the generation of a higher lift and thus helps in reducing the turning diameter of the vessel. The studies carried out with two rudder types — conventional rudder and fish tail shaped rudder — are presented in this paper. Numerical simulations are performed on these two rudders, both having the same surface area, for different rudder angles in free stream condition. The lift force generated by the fish tail shaped rudder is found to be higher than the conventional rudder. The flow across and the hydrodynamic forces acting on the sections are determined using a commercial CFD code. The effectiveness of the fishtail rudder is also brought out from the numerically simulated turning maneuver of a chosen ship fitted with the same rudder.

scholarly journals On the optimal control force applied to tuned mass dampers for multi-degree-of-freedom systems

2004 ◽  
Vol 26 (1) ◽  
pp. 1-10
Author(s):  
Nguyen Dong Anh ◽  
Nguyen Chi Sang
Keyword(s):  
Optimal Control ◽  
Numerical Study ◽  
Degree Of Freedom ◽  
Control Force ◽  
Linear Quadratic ◽  
Tuned Mass Dampers ◽  
Coloured Noise ◽  
Optimal Theory ◽  
The One ◽  
Better Than

The design of active TMD for multi-degree-of-freedom systems subjected to second order coloured noise excitation is considered using the linear quadratic optimal theory. A detailed numerical study is carried out for a 2-DOF system. It is shown that the effectiveness of active TMD is better than the one of passive TMD.

Development of a Multifactor Regression Model of Ship Maneuvering Forces Based on Optimized Captive-Model Tests

2006 ◽  
Vol 50 (04) ◽  
pp. 311-333 ◽  
Author(s):  
S. Sutulo ◽  
C. Guedes Soares
Keyword(s):  
Experimental Design ◽  
Polynomial Regression ◽  
Design Method ◽  
Model Tests ◽  
Ship Maneuvering ◽  
Captive Model Tests ◽  
Experimental Design Method ◽  
Force Moment ◽  
Force Components ◽  
Multifactor Regression

The paper provides the results of model tests planned with an optimized experimental design method. Captive-model tests have been carried out according to such a design on a computerized planar-motion carriage with a model of a fast catamaran with five varying factors (drift angle, rate-of-yaw amplitude, sinkage, trim and heel angles) and with all six force/moment components measured at each run. The measured values were used after preprocessing for construction of polynomial regression models for all force components acting upon the catamaran's hulls. It is demonstrated that the optimized experimental design method allows rather complicated mathematical models for maneuvering hydrodynamics forces to be obtained from captive model tests at a reasonable level of effort.

Effects of Hull and Control Surface Roughness on Ship Maneuvering

2020 ◽  
pp. 1-10
Author(s):  
John C. Daidola
Keyword(s):  
Surface Roughness ◽  
Equations Of Motion ◽  
Control Surface ◽  
Ship Maneuvering ◽  
Single Screw ◽  
Operation And Maintenance ◽  
Hydrodynamic Derivatives ◽  
Turning Maneuver ◽  
And Control ◽  
Surface Vessel

The effects of hull roughness on ship maneuvering characteristics are investigated. The hydrodynamic derivatives in the equations of motion for surface vessel maneuvering are modified to incorporate roughness of the hull and rudder. Vessel lifetime roughness profiles are postulated based on construction, coatings, operation, and maintenance for a vessel life of 25 years. These are then applied to the turning maneuver for single screw cargo ships with block coefficients from .60 to .80. The implications for naval missions are discussed.

scholarly journals Numerical study on the hydrodynamic performance of the semi-spade rudder and propeller

2019 ◽  
Vol 11 (1) ◽  
pp. 168781401882310 ◽  
Author(s):  
Xiao Yang ◽  
Yong Yin ◽  
Jing-Jing Lian
Keyword(s):  
Stokes Equations ◽  
Numerical Study ◽  
Turbulence Models ◽  
Suction Side ◽  
Hydrodynamic Performance ◽  
Computational Grids ◽  
Hydrodynamic Characteristics ◽  
Thrust Coefficient ◽  
Ship Maneuverability ◽  
Thrust And Torque

The semi-spade rudder and KP458 propeller of the KVLCC2 (KRISO very large crude carrier) model tanker are adopted by ITTC maneuvering technical committee in the comparative study of ship maneuverability. The incompressible viscous flow around semi-spade rudder and KP458 propeller is investigated using Reynolds-averaged Navier–Stokes equations, the computational grids are generated using ICEM software, and finite volume method is employed to discretize the governing equations. Combined with turbulence model, the hydrodynamic performance of semi-spade rudder is analyzed at different rudder angles, and the result provides a reference for the estimation of the hydrodynamic characteristics of semi-spade rudder. The multi-reference framework method is employed to carry out the numerical simulation of the flow field around the propeller. The thrust and torque of propeller under different turbulence models are calculated in the simulation. The thrust coefficient curve, torque coefficient curve, and efficiency curve are present. The pressure distributions of the pressure side and suction side of propeller blades are studied at different advance coefficient. Based on the study of the hydrodynamic performance of the semi-spade rudder and propeller, the propeller–rudder interaction is simulated and analyzed at different advance coefficient.

Numerical Study on the Maneuvering of a Ship in Waves Based on Unified State Space Model

2016 ◽  
Author(s):  
Rameesha Thayale Veedu ◽  
Parameswaran Krishnankutty
Keyword(s):  
State Space ◽  
Numerical Study ◽  
State Space Model ◽  
Container Ship ◽  
Regular Waves ◽  
Ship Maneuvering ◽  
Space Model ◽  
Water Conditions ◽  
Calm Water ◽  
Early Design Stages

Ship maneuvering performance is usually predicted in calm water conditions, which provide valuable information about ship’s turning ability and its directional stability in the early design stages. Investigation of maneuvering simulation in waves is more realistic since the ship usually sails through waves. So it is important to study the effect of waves on the turning ability of a ship. This paper presents the maneuvering simulation for a container ship in presence of regular waves based on unified state space model for ship maneuvering. Standard maneuvers like turning circle and zigzag maneuver are simulated for the head sea condition and the same are compared with calm water maneuvers. The present study shows that wave significantly affects the maneuvering characteristics of the ship and hence cannot be neglected.

Time Domain Analysis on Ship Maneuvering in Adverse Sea State

2016 ◽  
Author(s):  
Bingjie Guo ◽  
Ruth Eivind ◽  
Håvard Austefjord ◽  
Elzbieta M. Bitner-Gregersen ◽  
Olav Rognebakke
Keyword(s):  
Time Domain ◽  
Ghg Emissions ◽  
Weather Conditions ◽  
Time Domain Analysis ◽  
Equilibrium Analysis ◽  
Future Research ◽  
Ship Maneuvering ◽  
Ship Maneuverability ◽  
Adverse Weather ◽  
The Time Domain

Energy Efficiency Design Index (EEDI) introduced by the IMO Resolution MEPC.203 (62) has been the first initiative to regulate the greenhouse gas (GHG) emissions from ships. However, it has raised serious concerns that some ship designers might choose to lower the installed power to achieve EEDI requirements not accounting satisfactorily for ship safety. This has encouraged investigations addressing the ability of ship to maintain maneuverability in adverse sea states. The Interim Guidelines proposed in 2013, in IMO Res. MEPC.232 (65), recommend minimum propulsion power to maintain ship maneuvering ability in adverse weather conditions for bulk carriers and tankers. These guidelines are mainly based on statistical analysis and equilibrium analysis in a steady state. Today, most of the available tools and methods handle ship responses in waves by separating it into seakeeping and maneuvering. The present study investigates ship maneuverability by use of a recently developed time domain code which combines the sea-keeping and maneuvering equation to predict ship responses in waves. In this way, better insight into ship responses in adverse conditions is obtained. The numerical results presented in the study are validated by model tests. The limitations of the time-domain code are discussed and future research needs are pointed out.

scholarly journals Numerical Estimation of Hull Hydrodynamic Derivatives in Ship Maneuvering Prediction

2021 ◽  
Vol 28 (2) ◽  
pp. 46-53
Author(s):  
Radosław Kołodziej ◽  
Paweł Hoffmann
Keyword(s):  
Model Tests ◽  
Circular Motion ◽  
Computational Method ◽  
Design Stage ◽  
Hydrodynamic Characteristics ◽  
Ship Maneuvering ◽  
Hydrodynamic Derivatives ◽  
Captive Model Tests ◽  
Ship Maneuverability ◽  
Free Running

Abstract Prediction of the maneuvering characteristics of a ship at the design stage can be done by means of model tests, computational simulations or a combination of both. The model tests can be realized as a direct simulation of the standard maneuvers with the free running model, which gives the most accurate results but is also the least affordable, as it requires a very large tank or natural lake, as well as the complex equipment of the model. Alternatively, a captive model test can be used to identify the hydrodynamic characteristics of the hull, which can be used to simulate the standard maneuvers with the use of dedicated software. Two types of captive model tests are distinguished: circular motion tests (CMT) and planar motion mechanism tests (PMM). The paper presents an attempt to develop a computational method for ship maneuverability prediction in which the hydrodynamic characteristics of the hull are identified by means of computational fluid dynamics (CFD). The CFD analyses presented here directly simulate the circular motion test. The resulting hull characteristics are verified against the available literature data, and the results of the simulations are verified against the results of free running model tests. Reasonable agreement shows the large potential of the proposed method.

Effects of Hull Geometry and Tightness of Turns on Ship Maneuverability: An OSIS-IHI Simulation

2021 ◽  
Author(s):  
Michael Lau
Keyword(s):  
Performance Assessment ◽  
Ship Maneuvering ◽  
Hull Form ◽  
Structure Interaction ◽  
The Poor ◽  
Ship Maneuverability ◽  
Modeling Software ◽  
Body Design ◽  
Ship Performance ◽  
Shed Light

Abstract OSIS-IHI (Ocean Structure Interaction Simulator – Ice-Hull Interaction) is a ship maneuvering in ice modeling software developed at OCRE for a marine simulator and ship performance assessment applications. A series of OSIS-IHI simulations is conducted to explain the maneuvering behavior observed of the USCGC Polar Icebreaker indicative design previously tested at the centre. The simulation is conducted with the original and a modified version of the USCGC Icebreaker Healy. The Icebreaker USCGC Healy was equipped with doublescrew conventional propellers. The hull geometry of the OSIS-Healy model is appropriately modified to mimic the hull form of two indicated design versions in question and its propulsion units replaced by twin pods prior to studying its maneuverability in order to shed light on the apparently poor maneuvering performance of the podded version of the indicative design. The modified version extends the mid-body leaving just 7.5 % of hull that constitutes the stern section. It is hypothesized that the extended mid-section cost large resisting moment against turning due to the increase of ice breaking at the aft shoulder and mid-body. This hypothesis is validated numerically to explain the poor maneuverability exhibited by the extended mid-body design, based on consideration of ice-hull interaction geometry and basic mechanics of ice breaking as well as existing anecdotal test evidences. This paper presents result of the simulation to explore effects of hull geometry and tightness of turns on ship maneuverability. Important insights gained are summarized and recommendation for further work given.

Optimal Compliant Flapping Mechanism Topologies With Multiple Load Cases

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Bret Stanford ◽  
Philip Beran
Keyword(s):  
Aerodynamic Force ◽  
Compliant Mechanism ◽  
Micro Air Vehicles ◽  
Flapping Wing ◽  
Gradual Transition ◽  
Multiple Load Cases ◽  
Thrust Generation ◽  
Force Moment ◽  
Turning Maneuver ◽  
Multiple Load

The conceptual design of effective actuation mechanisms for flapping wing micro air vehicles presents considerable challenges, with competing weight, power, authority, and life cycle requirements. This work utilizes topology optimization to obtain compliant flapping mechanisms; this is a well-known tool, but the method is rarely extended to incorporate unsteady nonlinear aeroelastic physics, which must be accounted for in the design of flapping wing vehicles. Compliant mechanism topologies are specifically desired to perform two tasks: (1) propulsive thrust generation (symmetric motions of a left and a right wing) and (2) lateral roll moment generation (asymmetric motions). From an optimization standpoint, these two tasks are considered multiple load cases, implemented by scheduling the actuation applied to the mechanism’s design domain. Mechanism topologies obtained with various actuation-scheduling assumptions are provided, along with the resulting flapping wing motions and aerodynamic force/moment generation. Furthermore, it is demonstrated that both load cases may be used simultaneously for future vehicle control studies: gradual transition from forward flight into a turning maneuver, for example.

Light-Weight, Fast-Cycling, Shape-Memory Actuation Structures

2011 ◽  
Author(s):  
Aaron Stebner ◽  
Joseph Krueger ◽  
Anselm J. Neurohr ◽  
David C. Dunand ◽  
L. Catherine Brinson ◽  
...  
Keyword(s):  
Shape Memory ◽  
Surface Area ◽  
Numerical Study ◽  
Hot Isostatic Pressing ◽  
Milling Process ◽  
Constitutive Law ◽  
Micro Channel ◽  
Micro Channels ◽  
Increase Surface Area ◽  
Time Required

While bulk shape memory alloys (SMAs) have proven a successful means for creating adaptive aerospace structures in many demonstrations, including live flight tests, the time required to cool such actuators has been identified as a property that could inhibit their commercial implementation in some circumstances. To determine best practices for improving cooling times, several approaches to increase the surface area and reduce the mass of existing bulk actuator technologies have been examined. Specifically, geometries created using traditional milling and EDM techniques were compared with micro-channel geometries made possible by a new electrochemical milling process developed at Northwestern. The latter technique involves imbedding steel space-holders in a matrix of NiTi powders, hot isostatic pressing the preform into a dense composite, and then electro-chemically dissolving the steel. Thus, in a two-step process, it is possible to create an actuation structure with numerous micro-channels with excellent control of geometry, shape, size and placement, to reduce weight and increase surface area (and thus decrease response time) without compromising actuator performance. In this paper, the new, lighter-weight, faster cycling shape-memory alloy actuation structures resulting from each technique are reviewed. Their performances are compared and contrasted through the results of a numerical study conducted with a 3D SMA constitutive law developed specifically to handle the complex, non-proportional loadings that arise in porous structures. It is shown that using micro-channel technology, cooling times are significantly reduced relative to traditional machining techniques for the same amount of mass reduction.

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