CFD-BASED SIMULATION OF THE FLOW AROUND A SHIP IN OBLIQUE MOTION AT LOW SPEED

2021 ◽  
Vol 158 (A4) ◽  
Author(s):  
J Chen ◽  
Z J Zou ◽  
M Chen ◽  
H M Wang
Keyword(s):  
Verification And Validation ◽  
Hydrodynamic Performance ◽  
Dynamic Positioning ◽  
Drift Angle ◽  
Low Speed ◽  
Safety Issues ◽  
High Speeds ◽  
Ship Maneuverability ◽  
Ship Speed ◽  
Ship Flows

Ships tend to maneuver in oblique motion at low speed in situations such as turning in a harbor, or during offloading, dynamic positioning and mooring processes. The maneuverability criteria proposed by IMO are valid for ships sailing with relatively high speeds and small drift angles, which are inadequate to predict ship maneuverability in low speed condition. Hydrodynamic performance of ships maneuvering at low speed is needed to know for safety issues. A CFD-based method is employed to predict the flow around an Esso Osaka bare hull model in oblique motion at low speed, where the drift angle varies from 0° to 180°. The URANS method with the SST k-ω model is used for simulating ship flows with drift angles 0°~30° and 150°~180°, and DES method for simulating ship flows with drift angles 40°~150°. Verification and validation studies are conducted for drift angles of 0° and 70°. The vortex structures at typical drift angles of 0°, 30°, 50°, 70°, 90° and 180° are analyzed. The effects of drift angle and ship speed are demonstrated.

scholarly journals The Concept of Development and Implementation of High-Speed Transport

2020 ◽  
Vol 18 (1) ◽  
pp. 58-72
Author(s):  
V. M. Alexeev ◽  
A. V. Vaganov ◽  
M. V. Katina
Keyword(s):  
High Speed ◽  
Magnetic Levitation ◽  
Transport Systems ◽  
Rolling Stock ◽  
Design Elements ◽  
Safety Issues ◽  
Current Collection ◽  
High Speeds ◽  
Technical Solutions ◽  
Original Approach

The article discusses the issues of implementation and organization of high-speed transport. The objective of the article is to consider possible options for implementing highspeed (HS) motion systems using the principle of magnetic levitation, which will ensure high speeds for delivery of goods and carrying people over long distances. To achieve this objective, it is necessary to develop an engine and technical solutions for design of HS rolling stock, make decisions on energy supply infrastructure and the HS track, address safety issues and new control systems considering the state of the infrastructure and its design elements. The article discusses several options for implementation of high-speed transport systems, differing in the power supply system, current collection and track based on the magnetic levitation approach. An original approach is proposed in implementation of magnetic levitation transport using the technology of electromagnetic guns designed to implement traction forces of a magnetic levitation vehicle. The advantage of this approach is that it opens the possibility of maneuvering for the vehicle while driving. This allows to abandon switch turnouts, now significantly limiting the use of magnetic levitation transport. A mathematical model describing interaction of an electromagnetic gun and supermagnets located on the track is considered. In constructing the model, methods of the theory of electromagnetic field and interaction of magnetic bodies were used, and when constructing a model of interaction of rolling stock with a magnetic track, methods of mathematical algebra and the Cauchy theorem were used. The article discusses various principles of organization of movement using the magnetic levitation for urban, suburban, and intercity transport.

Development of a Ship Performance Simulator in Actual Seas

2015 ◽  
Author(s):  
Masaru Tsujimoto ◽  
Naoto Sogihara ◽  
Mariko Kuroda ◽  
Akiko Sakurada
Keyword(s):  
Energy Efficiency ◽  
Fuel Consumption ◽  
Hydrodynamic Performance ◽  
Wave Forces ◽  
Ship Hydrodynamic ◽  
Main Engine ◽  
Ship Performance ◽  
Actual Seas ◽  
Ship Speed ◽  
Drift Forces

Greenhouse gas shall be reduced from shipping sector. For that purpose the regulation of EEDI (energy efficiency design index for new ships) and SEEMP (ship energy efficiency management plan) were entry into force from 2013. In order to improve energy efficiency of ships in service it is necessary to predict the fuel consumption in actual seas. In order to reduce GHG emission from ships, a Vessel Performance Simulator in Actual Seas has been developed. It simulates ship speed and fuel consumption at steady condition by using weather data and designated engine revolution. Physical models for hull, propeller, rudder and engine are used in the simulator. Especially steady wave forces, wind forces, drift forces, steering forces and engine/governor model are important factor for the estimation. The fuel consumption should be evaluated combined the ship hydrodynamic performance with the engine/governor characteristics. Considering the external forces by winds and waves, the operation point of the main engine is important for the estimation, since the torque limit and the other limit of the engine/governor are affected to the ship hydrodynamic performance. To prevent the increase of fuel consumption in service, the engine control system by the Fuel Index has been applied to present ships. In rough weather condition the revolution of the main engine is reduced to lower revolution by the Fuel Index limit. It causes the large decrease of ship speed but reduces the fuel consumption due to reduction of engine revolution. Using the simulator the navigation performance of a container ship, a RoRo vehicle carrier and a bulk carrier is simulated along the route. In this paper following contents are discussed; 1) evaluation of the physical model; steady wave forces, wind forces, drift forces, steering forces and engine/governor model, 2) simulation and validation of the physical model by tank tests and on-board measurements and 3) effectiveness of the ship performance simulator for GHG reduction.

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.

scholarly journals The Influences of Lengthening Dimension of Ro-Ro Ferry Toward the Considerations of Hydrodynamics Characteristic and Loading Capacity Aspect

2019 ◽  
Vol 2 (1) ◽  
pp. 41-45
Author(s):  
Andi Rachmianty ◽  
Suandar Baso ◽  
Syamsul Asri
Keyword(s):  
Research Result ◽  
Loading Capacity ◽  
Total Resistance ◽  
Dimensional Parameter ◽  
Residual Resistance ◽  
High Speeds ◽  
Proper Design ◽  
The Difference ◽  
Ship Speed ◽  
Effective Speed

The ferry business has become an important business segment for ship designers, builders and operators. Therefore, many ways have been done in order to increase ferry business through the proper design or converting ships by lengthening. This research is focused on the influences of lengthening a Ro-Ro ferry to hydrodynamics characteristic and loading capacity aspects. Moreover, the ships also are fixed in the same width and draft dimensions. The difference of the Ro-Ro ferries length is indicated by the addition of one column of car space where one column car space is given by car size including distance between car columns spaces which is an increment of every 5.88 meter. The total resistances of Ro-Ro ferries are obtained by ship model experiment in towing tank. There are 4 ship models that are made. The lengthening a Ro-Ro ferry is described into non-dimensional parameter by the ratio of ship length and displacement volume (L/V1/3). The hydrodynamics and the loading capacity of carried car aspects could be described into the ratio of resistance and loading capacity of carried car (RT/SUK) with ship speed. The research result shows that the lengthening of a Ro-Ro ferry affects on total resistance, speed, and loading capacity of carried car. The increase of total resistance is caused by higher residual resistance at high speeds and this is experienced by small length size. Therefore by lengthening the Ro-Ro ferry it could reduce total resistance in the same speed especially the residuary resistance but eventhough lengthening Ro-Ro ferry the effective speed should be considered. In additions, the effective speed for actual ships dimension in the same Rt/SUK 0.05 i.e. B5L10 is about 13.85 knot, B5L11 14.33 knot, B5L12 14.94 knot, and B5L13 15.45 knot respectively.

Component-Based Development of Aeronautical Software

2010 ◽  
pp. 287-314
Author(s):  
Ítalo Romani de Oliveira ◽  
Ricardo Alexandre Veiga Gimenes ◽  
Jorge Rady de Almeida Jr.
Keyword(s):  
Software Development ◽  
Fuel Efficiency ◽  
Verification And Validation ◽  
Safety Issues ◽  
Safety Critical ◽  
Flight Stability ◽  
Component Based Development ◽  
Software Modules

Modern aircraft heavily relies on software to fly and operate, which lessens pilot workload, increases flight stability and fuel efficiency, and provides several other benefits. However, the more automated an aircraft is, the more prone to complexity its software modules are, raising special safety issues to be considered in the project. This chapter presents an overview of the Verification and Validation requirements for safety-critical software in aeronautics and, given the high costs to meet them, explains in detail a component-based methodology which can contribute to reduce the overall costs of software development and, at the same time, provide enhanced safety.

A Comparison of Alternative Bow Configurations

1995 ◽  
Vol 32 (03) ◽  
pp. 224-230
Author(s):  
Chel Stromgren
Keyword(s):  
State Of The Art ◽  
Computer Software ◽  
Hydrodynamic Performance ◽  
Construction Costs ◽  
Hull Form ◽  
Newport News ◽  
Standard Product ◽  
Computational Fluid Dynamics Cfd ◽  
Hydrodynamic Effects ◽  
Ship Speed

Newport News Shipbuilding (NNS) has been preparing for a reentry into the commercial shipbuilding market for several years. Those preparations resulted in the signing of a contract in October of 1994 with Eletson Corporation for the construction of two (with an option for an additional two)46500 dwt product carriers. This is the first contract for a U.S. shipyard to build commercial ships for a foreign owner in 37 years. In developing the hull form for the standard product carrier Double Eagle, NNS performed studies to determine the economic and hydrodynamic effects of alternative bow configurations on a representative modern, high-block tanker. The objectives of the study were to update the NNS commercial ship speed-power database, investigate the application of state of the art computer software, and create a bow design which strikes a balance between hydrodynamic performance and producibility. To achieve these goals, NNS worked with SAIC to use the computational fluid dynamics (CFD) SLAW software to mathematically analyze several candidate bows. These designs were then model tested at the Swedish State Model Basin in Gothenburg to validate the results of the CFD codes. Construction costs were then estimated for each design and finally, the bow forms were compared on an overall economic basis.

Mechatronic Design of Mobile Robots for Stable Obstacle Crossing at Low and High Speeds

2015 ◽  
pp. 567-630
Author(s):  
Jean-Christophe Fauroux ◽  
Frédéric Chapelle ◽  
Belhassen-Chedli Bouzgarrou ◽  
Philippe Vaslin ◽  
Mohamed Krid ◽  
...  
Keyword(s):  
Mobile Robot ◽  
Mobile Robots ◽  
High Speed ◽  
Legged Locomotion ◽  
Improve Performance ◽  
Obstacle Crossing ◽  
Low Speed ◽  
Pitch Control ◽  
High Speeds ◽  
Hybrid Locomotion

This chapter presents recent mechatronics developments to create original terrestrial mobile robots capable of crossing obstacles and maintaining their stability on irregular grounds. Obstacle crossing is both considered at low and high speeds. The developed robots use wheeled propulsion, efficient on smooth grounds, and improve performance on irregular grounds with additional mobilities, bringing them closer to legged locomotion (hybrid locomotion). Two sections are dedicated to low speed obstacle crossing. Section two presents an original mobile robot combining four actuated wheels with an articulated frame to improve obstacle climbing. Section three extends this work to a new concept of modular poly-robot for agile transport of long payloads. The last two sections deal with high-speed motion. Section four describes new suspensions with four mobilities that maintain pitch stability of vehicles crossing obstacles at high speed. After the shock, section five demonstrates stable pitch control during ballistic phase by accelerating-braking the wheels in flight.

Safety Perceptions and Information Sources for ATVs

1988 ◽  
Vol 32 (15) ◽  
pp. 938-942
Author(s):  
Edward W. Karnes ◽  
S. David Leonard ◽  
Herbert C. Newbold
Keyword(s):  
Human Factors ◽  
Information Sources ◽  
Consumer Information ◽  
Safety Issues ◽  
Safety Perceptions ◽  
High Speeds ◽  
Low Speeds

Safety issues concerning all-terrain vehicles (ATVs) have become important for human factors professionals, becasuse of the need to reduce the accidents and injuries associated with their use. Human factors experts have also been called upon to testify in legal suits occasioned by some accidents. This paper discusses some of the problems associated with the safety of ATVs and presents data concerning riders and observers ability to estimate their speed. Speed estimates are lower than actual speeds at low speeds and higher than actual speeds at high speeds. It is concluded that information about the speed capabilities of ATVs is important consumer information and should be made conspicuous in advertising and other informational channels about ATVs.

Outcomes From a Study of Validation of Ship Specific Models for Shiphandling Simulator

2017 ◽  
Author(s):  
Tor E. Berg ◽  
Ørjan Selvik
Keyword(s):  
Model Development ◽  
Simulation Models ◽  
Model Tests ◽  
The Other ◽  
Dynamic Positioning ◽  
Research Project ◽  
Low Speed ◽  
Validation Methods ◽  
Development And Validation

This paper presents some outcomes from a four years (2013 – 2016) long research project investigating validation of ship specific simulation models. In contrast to the other initiatives such as SIMMAN 2008 [1] and SIMMAN 2014 [2], the R&D project “Sea Trials and Model Tests for Validation of Shiphandling Simulation Models” (SIMVAL [3]) investigates model development and validation methods for specific vessels. For these vessels, the yard’s documentation of manoeuvring characteristic was available for the researchers. In addition, the project has been given permission to perform different sets of sea trials on selected case vessels. As far as possible, these sea trials were designed to document vessel-specific operations such as low-speed manoeuvres and dynamic positioning. Other papers presenting results from the SIMVAL project will be given in a separate session, Session 12–14, in the Torgeir Moan Symposium at OMAE2017.

Comparative Performance of Optimum High Speed SWATH and Semi-SWATH in Calm Water and in Waves

2015 ◽  
Author(s):  
S. Brizzolara ◽  
G. Vernengo ◽  
L. Bonfiglio ◽  
D. Bruzzone
Keyword(s):  
High Speed ◽  
Hydrodynamic Performance ◽  
Forward Speed ◽  
Comparative Performance ◽  
Hull Form ◽  
High Speeds ◽  
Head Waves ◽  
Calm Water ◽  
Minimization Algorithms ◽  
Ranse Solver

The hydrodynamic performance of unconventional SWATH and Semi-SWATH for high speed applications are analyzed and compared in this paper. Bare hull resistance in calm water is estimated by an inviscid boundary element method with viscous corrections and verified by a fully turbulent, multiphase unsteady RANSE solver. Motions response in head waves, calculated by a frequency domain 3D panel method with forward speed effects are also evaluated and compared. Both considered hulls are the best designs coming from full parametric hull form optimization procedures, based on CFD solvers for the estimation of their hydrodynamic performance and driven by evolutionary minimization algorithms. The SWATH has twin parabolic struts and an unconventional underwater shape, the semi-SWATH has a slender triangular waterline, a bulbous shape in the entrance body which gradually morph into a U-section with a shallow transom in the run body. In general, as expected, the Semi-SWATH hull shows a lower drag at high speeds while the single strut SWATH is superior at lower speeds. As regards seakeeping, the SWATH shows unbeatable lower pitch and heave motions in shorter waves, where the Semi-SWATH evidences a double peaked RAO. More detailed analysis and conclusion are drawn in the paper.

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