The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform

Shin Hyung Rhee - One of the best experts on this subject based on the ideXlab platform.

  • Towed underwater PIV measurement of propeller wake in self-propelled condition
    Experiments in Fluids, 2019
    Co-Authors: Seok Cheon Go, Jongyeol Park, Shin Hyung Rhee
    Abstract:

    A series of particle image velocimetry measurements was conducted in a towing tank to analyze the propeller wake dynamics of a fully appended very large crude oil carrier model. The Froude number and the Reynolds number of the test condition based on the model length and towing speed were 0.142 and 2.32 × 10^6, respectively. The propeller wake dynamics was investigated in terms of vortical structure and wake acceleration. It was found that the propeller loading on the Starboard Side was larger than that on the port Side, as upward component of the propeller inflow resulted in a higher inflow speed on that Side. The different propeller loading deformed the wake structure and bent it towards the port Side. Between neighboring tip vortices, the local maxima of the turbulence kinetic energy and corresponding local turbulence structure were found. The rudder effects on the propeller wake were also investigated, proving that the rudder blocked the progress of the hub vortex and straightened the propeller wake. Graphic abstract

  • Propeller Wake Measurement of a Model Ship in Self Propulsion Condition using Towed Underwater PIV
    Journal of the Society of Naval Architects of Korea, 2014
    Co-Authors: Jeonghwa Seo, Geuk Sang Yoo, Tae Gu Lim, Dong Myung Seol, Bum Woo Han, Shin Hyung Rhee
    Abstract:

    A two-dimensional particle image velocimetry (2D PIV) system in a towing tank is employed to measure a wake field of a very large crude oil carrier model with rotating propeller in self propulsion condition, to identify characteristics of wake of a propeller working behind a ship. Phase-averaged and time-averaged flow fields are measured for a horizontal plane. Scale ratio of the model ship is 1/100 and Froude number is 0.142. By phase-averaging technique, trajectories of tip vortex and hub vortex are identified and characteristic secondary vortex distribution is observed in the hub vortex region. Propeller wake on the Starboard Side is more accelerated than that on the port Side, due to the difference of inflow of propeller blades. The hub vortex trajectory tends to face the port Side. With the fluctuation part of the phase-averaged velocity field, turbulent kinetic energy (TKE) is also derived. In the center of tip vortex and hub vortex region, high TKE concentration is observed. In addition, a time-averaged vector field is also measured and compared with phase-averaged vector field.

Jeung-hoon Lee - One of the best experts on this subject based on the ideXlab platform.

  • Sea-trial verification of ultrasonic antifouling control.
    Biofouling, 2017
    Co-Authors: Ji-soo Park, Jeung-hoon Lee
    Abstract:

    An ultrasonic antifouling treatment was applied to a 96,000 m3 class drill-ship to verify its feasibility through a sea-trial. Soon after the hull cleaning had been performed, six ultrasonic projectors were evenly deployed around the Starboard shell plate. Driven by a 23 kHz sinusoidal ultrasound in an intermittent manner, the projectors emitted a high-intensity sound reaching 214 dB at the source level causing cavitation around the adjacent water and eventually deterring the settlement of marine fouling organisms. Underwater photographs acquired after four months showed fairly clean slabs on the Starboard Side, but heavy fouling on the port Side. This experiment revealed that ultrasound treatment is a promising method for inhibiting fouling accumulation, even for large-scale ship applications.

B Sahin - One of the best experts on this subject based on the ideXlab platform.

  • The Obligations of Single-Propeller Vessels at the Head-On Situation
    TransNav the International Journal on Marine Navigation and Safety of Sea Transportation, 2016
    Co-Authors: B Sahin
    Abstract:

    Maneuvering characteristics of the vessels at the head-on situation are examined in this study. The meetings between the power-driven vessels are conSidered based on their propellers. These vessels can either have a single propeller or double propellers. A vessel with a single right-handed propeller alters her course to port Side easier than the Starboard Side. There exists an unnoticed gap, therefore the authors discuss the International Regulations for Preventing Collisions at Sea, 1972 (COLREGs), Rule 14, conSidering the vessel orientation based on its propeller walk. After presenting all possible cases and their probable consequences, this paper offers authorities to embed the information of propeller characteristics into the Automatic Identification Systems (AIS) in order to prevent misunderstandings during the VHF communications, probable collision risks and discussions on liability issues in case of marine accidents.

  • The Obligations of Single-Propeller Vessels at the Head-On Situation
    Gdynia Maritime University, 2016
    Co-Authors: B Sahin
    Abstract:

    Manoeuvring characteristics of the vessels at the head-on situation are examined in this study. The meetings between the power-driven vessels are conSidered based on their propellers. These vessels can either have a single propeller or double propellers. A vessel with a single right-handed propeller alters her course to port Side easier than the Starboard Side. There exists an unnoticed gap, therefore the authors discuss the International Regulations for Preventing Collisions at Sea, 1972 (COLREGs), Rule 14, conSidering the vessel orientation based on its propeller walk. After presenting all possible cases and their probable consequences, this paper offers authorities to embed the information of propeller characteristics into the Automatic Identification Systems (AIS) in order to prevent misunderstandings during the VHF communications, probable collision risks and discussions on liability issues in case of marine accidents

William M. Leary - One of the best experts on this subject based on the ideXlab platform.

Wang J. - One of the best experts on this subject based on the ideXlab platform.

  • Comprehensive numerical simulations of a tanker collision with a bergy bit incorporating damage to the vessel
    Dalian University of Technology Press, 2013
    Co-Authors: Gagnon R. E., Wang J.
    Abstract:

    Numerical simulations of a collision between a loaded tanker and a bergy bit have been conducted using LS-DynaTM software. The simulation incorporated hydrodynamics, via LSDyna\u2019s ALE formulation, and a validated crushable foam ice model. The major portion of the vessel was treated as a rigid body and a section of the hull, located on the Starboard Side of the forward bow where the ice contact occurred, was modeled as typical ship grillage that could deform and sustain damage as a result of the collision. Strategies for dealing with the highly varying mesh densities needed for the simulation are discussed as well as load and pressure distribution throughout the course of the collision. Realistic movement of the bergy bit due to the vessel\u2019s bow wave prior to contact with the ice was observed and the damage to the grillage in the initial stage of the collision resembled results from actual grillage damage tests in the lab. The collision eventually ruptured the hull in a ripping fashion resembling documented incidents.Peer reviewed: YesNRC publication: Ye

  • Numerical simulations of a tanker collision with a bergy bit incorporating hydrodynamics, a validated ice model and damage to the vessel
    2012
    Co-Authors: Gagnon R. E., Wang J.
    Abstract:

    Numerical simulations of a collision between a loaded tanker and a bergy bit have been conducted using LSDyna \u2122 software. The simulations incorporated hydrodynamics, via LS-Dyna's ALE formulation, and a validated crushable foam ice model. The major portion of the vessel was treated as a rigid body and a section of the hull, located on the Starboard Side of the forward bow where the ice contact occurred, was modeled as typical ship grillage that could deform and sustain damage as a result of the collision. Strategies for dealing with the highly varying mesh densities needed for the simulations are discussed as well as load and pressure distribution on the grillage throughout the course of the collision. Realistic movement of the bergy bit due to the vessel's bow wave prior to contact with the ice was observed and the damage to the grillage resembled published results from actual grillage damage tests in the lab. A load measurement from the lab tests compared reasonably well with a rough estimate from the simulation. The collision eventually ruptured the hull in a ripping fashion resembling documented incidents of vessel impacts with ice masses.Peer reviewed: YesNRC publication: Ye