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    Impelementation of Numerical Method For Hydrodynamic Behavior for Salvage of a Sunken Ship

    , M.Sc. Thesis Sharif University of Technology Jelodari, Ehsan (Author) ; Abbaspour, Majid (Supervisor)
    One of the utmost important factors during salvage operation of drowned ships is raising velocity. Uncontrolled raise is a dynamic phenomenon which can lead to the sudden tensions, collapse in airbags or ships. Studing this issue helps the engineers which kinds of problems are more important during salvage operations. This study focus on modeling and analysis of raising movment of the ship with FLOW-3D and ABAQUS software.
    In FLOW-3D environment, hydrodynamic analysis of rising movment of drowned ship has been done. We should mention that applied forces and velocities and other parameters from the FLOW-3D output should be passed IMCA Criteria to avoid uncontrollable raise. In ABAQUS... 

    Hydrodynamic Modeling of an AUV

    , M.Sc. Thesis Sharif University of Technology Fesanghari, Majid (Author) ; Sayyadi, Hassan (Supervisor)
    Autonomous underwater vehicles (AUVs) are a type of marine vehicles which are currently being used for exploration, maintenance, repairing of marine structures and military appliances. Unmanned underwater vehicles categorize in two types: ROVs and AUVs, ROVs (remotely operated vehicles) usually are connected to the mother vessel with a cable, conduction signals transfer through this cable and there is an operator in the control loop. The vehicle may be fed up with this cable, AUVs are modern underwater vehicles which the operator on controlling and conducting is removed, there is no connection between the vehicle and mother vessel, energy sources and controlling orders are set up in the... 

    Maneuver Modeling and Nonlinear Analysis of a High Speed Ship Considering Thrusting and Propulsive Systems

    , M.Sc. Thesis Sharif University of Technology Miraki Baseri, Rahim (Author) ; Sayyadi, Hassan (Supervisor) ; Mehdigholi, Hamid (Co-Advisor)
    Ship maneuverability is so important from different aspects. According to the regulations of International Maritime Organization (IMO), every vessel has to meet the minimum requirements of mentioned rules. Consequently, prediction of ship maneuverability in early stages of the ship design has become to one of the most necessary steps for shipbuilding and design companies. In this research work maneuvering of a high speed ship has been investigated using three different propulsive modes, considering propeller and rudder systems, azipod propeller and waterjet systems. First of all, hydrodynamics equations of each cases while considering different motion modes such as surge, sway, yaw, and roll... 

    Hydrodynamic Analysis of “Persian Gulf” Bridge and Feasibility Study of Using Energy Production Systems on the Bridge Structure

    , M.Sc. Thesis Sharif University of Technology Seifollahi, Ali (Author) ; Abbaspour, Majid (Supervisor)
    Nowadays, because high global demand for energy has led to the extensive use of fossil fuels with numerous unintended consequences such as air pollution and greenhouse effect, research and development around optimization of energy infrastructure has become much more important. Consequently, many scientific approaches have been applied to replace fossil fuels with renewable natural energy resources. One of the renewable energy types that fewer papers have been published about it, is the enormous energy of Marine currents. The origin of this energy is mostly tidal effect, or ocean currents that are available in most of oceans and seas around the planet earth. The most important criteria for... 

    Numerical and experimental study of a jet impinging with axial symmetry with a set of heat exchanger tubes

    , Article Mechanics and Industry ; Volume 19, Issue 1 , 2018 ; 22577777 (ISSN) Jamalei, E ; Alayi, R ; Kasaeian, A ; Kasaeian, F ; Ahmadi, M. H ; Sharif University of Technology
    EDP Sciences  2018
    The main purpose of this research is to predict the flow field of impinging turbulent jet with cylinder in a 3-d state. Nowadays, shear stress has multiple uses in the industry. The study has been conducted in both compressible and incompressible states with output velocities between 100 and 150 m/s, in different eccentricities of jet with respect to the first cylinder, and in various nozzle outlet orifice distances from front edge of the first cylinder. Pressure distribution and shear stress on cylinder surfaces have been determined and efficiency of jet in cleaning the heat exchangers pipes has been analyzed. Also, an experimental investigation has been conducted in order to verify the... 

    Hydroelastic Analysis of Surface Piercing Propeller

    , M.Sc. Thesis Sharif University of Technology Fatemeh, Shahreki (Author) ; Seif, Mohamad Saeed (Supervisor)
    Surface piercing propellers are particular type of supercavitating propellers that are commonly used for High-speed vessels. Most studies on this type of propellers has been investigating the hydrodynamic forces. But in recent years with increase in SPPs diameter used in vessels, structural analysis of this type of propellers is considered. For this purpose, studies on the stresses exerted on the propeller structures under load is done with the help of Hydro elastic methods. In this type of analysis, structura of propeller is intended to be flexible and Displacements under pressure checked and Tensions resulting from it are studied.
    The present Thesis using ANSYS software to analyze a... 

    PELAMIS’s Hydro Dynamical Analyses and Mechanism Design of Wave Energy Converter Device (Semi-PELAMIS)

    , M.Sc. Thesis Sharif University of Technology Saeidi Hamid Abad, Mohammad (Author) ; AbbasPour, Majid (Supervisor)
    Pelamis is a semi-submersible device that can extract wave energy and converters that to electrical power. It has 5 cylindrical structure that connects through the joints. This device takes the shape of wave and the wave forces tubes to had angular relative motion together. The Main task of this device is to convert the angular movements of tubes to the Linear movement of pistons. External mechanism called the energy capture device are responsible for absorbing wave energy through angular movements, and then the internal mechanism, called the Power Take-Off, are responsible for converting this energy into the electrical power for use in the electricity grid. This device was designed and... 

    Using sensitivity analysis and gradual evaluation of ignition delay error to produce accurate low-cost skeletal mechanisms for oxidation of hydrocarbon fuels under high-temperature conditions

    , Article Energy and Fuels ; Volume 31, Issue 10 , 2017 , Pages 11234-11252 ; 08870624 (ISSN) Shakeri, A ; Mazaheri, K ; Owliya, M ; Sharif University of Technology
    Three-dimensional thermo-hydrodynamic analysis of gas turbine combustion chambers is of great importance in the power generation industry to achieve higher efficiency and reduced emissions. However, it is prohibitive to use a comprehensive full-detailed mechanism in their simulation algorithms because of the huge CPU time and memory space requirements. Many reduction approaches are available in the literature to remedy this problem. Here a new approach is presented to reduce large detailed or skeletal mechanisms of oxidation of hydrocarbon fuels to a low-cost skeletal mechanism. The method involves an integrated procedure including a Sensitivity Analysis (SA) and a procedure of Gradual... 

    Numerical study and acoustic analysis of propeller and hull surface vessel in self-propulsion mode

    , Article Ships and Offshore Structures ; 2021 ; 17445302 (ISSN) Raghebi, M ; Norouzi Keshtan, M ; Malek Jafarian, M ; Bagheri, M. R ; Sharif University of Technology
    Taylor and Francis Ltd  2021
    In this article, the hydrodynamic analysis and noise of the propeller and the surface vessel hull were examined. The model selected in this study is a KRISO Container Ship (KCS) with a five-bladed propeller. Initially, the hydrodynamic analysis of the propeller in open water mode and then in self-propulsion mode was investigated using computational fluid dynamics. Simulations were carried out using a commercial solver, STAR-CCM+ (RANS equations with FVM and VOF model). Finally, the emitted noise from the propeller and the vessel hull was investigated using Fox William Hawkins equations. The pressure distribution and hydrodynamic performance (thrust, torque, efficiency) of the propeller in... 

    Conceptual study on dynamic response of semi-submersible

    , Article Proceedings of the Institution of Civil Engineers: Maritime Engineering ; 2021 ; 17417597 (ISSN) Tabeshpour, M. R ; Hajnoruzi, F ; Sharif University of Technology
    ICE Publishing  2021
    Hydrodynamic analysis of semi-submersible offshore structures has been the topic of many researches performed numerically and experimentally in the past. In this paper, the effect of structure alignment and mooring lines on dynamic behaviour of semi-submersible platforms has been taken into account. The contribution of pitch and roll in heave motion of side points is also investigated. Mooring lines are connected to semi-submersible at sides and therefore total displacement of side points is related to total displacement of mooring lines and total tension as well. A three dimensional boundary element model of Amirkabir platform in Caspian Sea is implemented using boundary element method... 

    A unified computational method for simulating dynamic behavior of planing vessels

    , Article China Ocean Engineering ; Volume 23, Issue 3 , 2009 , Pages 517-528 ; 08905487 (ISSN) Seif, M. S ; Jahanbakhsh, E ; Panahi, R ; Karimi, M. H ; Sharif University of Technology
    High speed planing hulls have complex hydrodynamic behaviors. The trim angle and drafts are very sensitive to speed and location of the center of gravity. Therefore, motion simulation for such vessels needs a strong coupling between rigid body motions and hydrodynamic analysis. In addition, free surface should be predicted with good accuracy for each time step. In this paper, velocity and pressure fields are coupled by use of the fractional step method. On the basis of integration of the two-phase viscous flow induced stresses over the hull, acting loads (forces and moments) are calculated. With the strategy of boundary-fitted body-attached mesh and calculation of 6-DoF motions in each time... 

    Positioning and tracking control of an amphibious single wheel robot

    , Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 11 , 2009 , Pages 545-551 ; 9780791848722 (ISBN) Marzban, M ; Alizadeh, D ; Sharif University of Technology
    Amphibious single wheel robot consists of a sharp-edged wheel actuated by a spinning flywheel for steering and a drive motor for propulsion. The spinning flywheel acts as a gyroscope to stabilize the robot and also can be tilted to achieve steering. In this paper, the kinematics of a single wheel robot in water, Gyrover, is analyzed and then a simple mechanism for driving it is proposed. In previous studies, Lagrange approach is used for hydrodynamic modeling of the robot. A nonlinear position controller is designed to bring the robot to any desired position. Based on the designed controller, a tracking controller is augmented to the robot. For simplicity the added mass effect has been... 

    Dynamic anlysis of an amphibious single wheel robot part1: Moving in straight path

    , Article 31st Mechanisms and Robotics Conference, presented at - 2007 ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, IDETC/CIE2007, Las Vegas, NV, 4 September 2007 through 7 September 2007 ; Volume 8 PART B , 2008 , Pages 927-932 ; 0791848027 (ISBN); 9780791848029 (ISBN); 0791848094 (ISBN); 9780791848098 (ISBN) Marzban, M ; Alasty, A ; Sharif University of Technology
    A single wheel, gyroscopically stabilized robot is a sharpedged wheel actuated by a spinning flywheel for steering and a drive motor for propulsion. The spinning flywheel acts as a gyroscope to stabilize the robot and it can be tilted to achieve steering. In this paper first the kinematics of a single wheel robot, like Gyrover, in water is considered and then a simple mechanism for its movement in water is proposed. After hydrodynamic analysis of the robot a complete dynamics model is designed with Lagrange energy method. The only simplification used here is neglecting the added mass effect in hydrodynamic analysis. This complete model can be used for examining the behavior of the robot in... 

    Stability control of an Amphibious single wheel robot

    , Article ASME International Mechanical Engineering Congress and Exposition, IMECE 2007, Seattle, WA, 11 November 2007 through 15 November 2007 ; Volume 9 PART B , 2008 , Pages 1465-1472 ; 0791843033 (ISBN); 9780791843031 (ISBN) Marzban, M ; Alasty, A ; Sharif University of Technology
    Single wheel robots are typically those kinds of robots which contain all the necessary mechanizations, namely the stabilization and driving mechanizations, within a shell-liked housing appearing analogous to a wheel. These robots have proved to be useful in various fields of industry due to their advantages of giving high instant acceleration and maintaining high cruise speeds for considerable amount of time in addition to being compact and small. It is a sharp-edged wheel actuated by a spinning flywheel for steering and a drive motor for propulsion. The spinning flywheel acts as a gyroscope to stabilize the robot and it can be tilted to achieve steering. In this paper first the kinematics...