The Experts below are selected from a list of 12 Experts worldwide ranked by ideXlab platform

V. Anantha Subramanian - One of the best experts on this subject based on the ideXlab platform.

  • Estimation of hull-propeller interaction of a self-propelling model hull using a RANSE solver
    Ships and Offshore Structures, 2010
    Co-Authors: G. Dhinesh, K. Murali, V. Anantha Subramanian
    Abstract:

    Viscous flow around the self-propelled hull was investigated at model scale with a RANSE solver using k-ϵ turbulence model by coupling the flow around the hull model with the flow generated by the rotating propeller. Hence, the challenges involved in the coupling of flow past ship hull with propeller flow of lower-order scale have been brought out and addressed here. Propeller rotation is accounted for by mesh motion; the solution domain is represented by a rotating cylindrical domain encompassing the propeller and a fixed rectangular domain around the hull for the remaining part of the solution domain; both these domains are interfaced by sliding interfaces. Comparisons are made between the simulated results and corresponding experimental results for hull resistance, propeller Thrust and propeller RPM. It is shown that the flow field in the self-propelling condition is well reproduced in the simulation, and the estimated Thrust Deduction Factor and RPM agree well with the measured ones. Among the various...

Hamburg Univ. Inst. Fuer Schiffbau - One of the best experts on this subject based on the ideXlab platform.

  • Beitrag zur Abschaetzung von Widerstand und Propulsion von Ein- und Zweischraubenschiffen im Vorentwurf
    1997
    Co-Authors: Hollenbach K.u., Hamburg Univ. Inst. Fuer Schiffbau
    Abstract:

    With a view to improve reliability of the performance prognosis of modern merchant vessels in the preliminary design stage, model tank tests performed by the Vienna Ship Model Basin of the period from 1980 to 1995 have been analysed. The resistance test results are compared with the different statistical methods. The open water test results of stockpropellers are compared with the propeller efficiencies of the Wageninger B-screw series. For the model experiment results available a PC program for database-based ship trial prognosis has been developed. In addition to the database-based method a novel statistical method for estimating the ships resistance has been developed. This method is intended to enable estimating not only a mean resistance, but also the minimum resistance of good lines and the maximum resistance of poor lines. Furthermore formulas for estimating the wake Factor, the Thrust Deduction Factor and the relative rotative efficiency for single and twin screw vessels are presented. The novel statistical method for resistance and propulsion Factors has been tested with a control group of ship models which recently have been tested at the Hamburg Ship Model Basin (HSVA). (orig.)SIGLEAvailable from TIB Hannover: RA 489(588) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

X U Wenshan - One of the best experts on this subject based on the ideXlab platform.

  • mechanism of negative Thrust Deduction Factor of waterjet hull
    Chinese Journal of Hydrodynamics, 2011
    Co-Authors: X U Wenshan
    Abstract:

    This paper attempts to explain the mechanism of negative Thrust Deduction Factor of waterjet drived hull that is discovered at waterjet-hull interaction researches.Flow fields of waterjet self-propulsion model are derived by solving RANS equations with taking into account the hull trim and sinkage.Waterjet pump effect is modeled by CFD boundary conditions.Major mechanisms responsible for the negative Thrust Deduction Factor are researched.These include flow field,hull trim and sinkage changes due to the presence of the waterjet.The results show that hull stern flow is not accelerated by jet flow as the nozzle is above the free surface and the case is greatly different from propeller drived hull.The intake flow only accelerates the stern flow at low hull speed case and added hull pressure resistance is presented as the positive Thrust Deduction Factor.However for middle/high speeds cases,the intake flow changes the boundary layer which reduces hull viscous resistance and makes the appearance of negative Thrust Deduction Factors.Forces acting on the duct are trending to reduce the hull trim and sinkage and the effect is more important at high speed but it is not the main reason responsible for the negative Thrust Deduction Factor.

G. Dhinesh - One of the best experts on this subject based on the ideXlab platform.

  • Estimation of hull-propeller interaction of a self-propelling model hull using a RANSE solver
    Ships and Offshore Structures, 2010
    Co-Authors: G. Dhinesh, K. Murali, V. Anantha Subramanian
    Abstract:

    Viscous flow around the self-propelled hull was investigated at model scale with a RANSE solver using k-ϵ turbulence model by coupling the flow around the hull model with the flow generated by the rotating propeller. Hence, the challenges involved in the coupling of flow past ship hull with propeller flow of lower-order scale have been brought out and addressed here. Propeller rotation is accounted for by mesh motion; the solution domain is represented by a rotating cylindrical domain encompassing the propeller and a fixed rectangular domain around the hull for the remaining part of the solution domain; both these domains are interfaced by sliding interfaces. Comparisons are made between the simulated results and corresponding experimental results for hull resistance, propeller Thrust and propeller RPM. It is shown that the flow field in the self-propelling condition is well reproduced in the simulation, and the estimated Thrust Deduction Factor and RPM agree well with the measured ones. Among the various...

Zhuxin Zhang - One of the best experts on this subject based on the ideXlab platform.

  • research on design method of the full form ship with minimum Thrust Deduction Factor
    China Ocean Engineering, 2015
    Co-Authors: Baoji Zhang, Aiqin Miao, Zhuxin Zhang
    Abstract:

    In the preliminary design stage of the full form ships, in order to obtain a hull form with low resistance and maximum propulsion efficiency, an optimization design program for a full form ship with the minimum Thrust Deduction Factor has been developed, which combined the potential flow theory and boundary layer theory with the optimization technique. In the optimization process, the Sequential Unconstrained Minimization Technique (SUMT) interior point method of Nonlinear Programming (NLP) was proposed with the minimum Thrust Deduction Factor as the objective function. An appropriate displacement is a basic constraint condition, and the boundary layer separation is an additional one. The parameters of the hull form modification function are used as design variables. At last, the numerical optimization example for lines of after-body of 50000 DWT product oil tanker was provided, which indicated that the propulsion efficiency was improved distinctly by this optimal design method.