Bulgarian Ship Hydrodynamics Center

Bulgarian, Bulgaria

Bulgarian Ship Hydrodynamics Center

Bulgarian, Bulgaria
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Kandasamy M.,University of Iowa | Peri D.,CNR Italian Ship Model Basin | Tahara Y.,Japan National Maritime Research Institute | Wilson W.,Naval Surface Warfare Center Carderock Division | And 5 more authors.
International Shipbuilding Progress | Year: 2013

The present work focuses on the application of simulation-based design for the resistance optimization of waterjet propelled Delft catamaran, using integrated computational and experimental fluid dynamics. A variable physics/variable fidelity approach was implemented wherein the objective function was evaluated using both low fidelity potential flow solvers with a simplified CFD waterjet model and high fidelity RANS solvers with discretized duct flow calculations. Both solvers were verified and validated with data for the original hull. The particle swarm optimizer was used for single speed optimization at Fr=0.5, and genetic algorithms were used for multi speed optimization at Fr=0.3, 0.5 and 0.7. The variable physics/variable fidelity approach was compared with high fidelity approach for the bare-hull shape optimization and it showed an overall CPU time reduction of 54% and converged to the same optimal design at Fr=0.5. The multi-speed optimization showed design improvement at Fr=0.5 and 0.7, but not at Fr=0.3 since the design variables were obtained based on sensitivity analysis at Fr=0.5. High fidelity simulation results for the optimized barehull geometry indicated 4% reduction in resistance and the optimized waterjet equipped geometry indicated 11% reduction in effective pump power required at self-propulsion. Verification was performed for the optimized hull form and its reduction in powering will be validated in forthcoming experimental campaign. © 2013 - IOS Press and the authors. All rights reserved.

Milanov E.,Bulgarian Ship Hydrodynamics Center | Zlatev Z.,Bulgarian Ship Hydrodynamics Center | Chotukova V.,Bulgarian Ship Hydrodynamics Center | Stern F.,University of Iowa
International Shipbuilding Progress | Year: 2011

The paper treats the important problem of prediction of ship's inherent course stability, based on a large amount of model experimental data for a well-known bare hull shape - the Delft catamaran 372, covering a comparatively wide range of Froude numbers and depth to draught ratios. The analysis is based on a linearized maneuvering model. As a result, dependency of the stability criterion on Froude number and the water depth to draught ratio is established and clearly demonstrated for this particular ship case. © 2011 IOS Press and the authors. All rights reserved.

Sadat-Hosseini H.,University of Iowa | Chen X.,University of Iowa | Kim D.H.,University of Iowa | Milanov E.,Bulgarian Ship Hydrodynamics Center | And 3 more authors.
FAST 2013 - 12th International Conference on Fast Sea Transportation | Year: 2013

Free running simulations of Delft Catamaran with water-jet propulsion system are conducted for turning and zigzag maneuver. The simulations are conducted either for bare hull with integral force models for water-jet or with actual water-jet with body force impeller defined by pump curves with different slopes. Additionally, captive simulations are conducted for bare hull resistance test to predict the required thrust force for water-jet models and free running self-propulsion simulations are conducted to estimate the required propeller RPS for actual water-jet simulations. CFD results are compared with system-based predictions and both validated against EFD data. Turning maneuver simulations showed average error of 7.6% for SB method and 9-22.6%D for CFD simulations with minimum error for the actual water-jet simulation with highest slope pump curve. Zigzag maneuver showed large errors for CFD with actual water-jet while good agreement is shown for CFD bare hull with system based integral force water-jet model.

Kandasamy M.,University of Iowa | Georgiev S.,Bulgarian Ship Hydrodynamics Center | Milanov E.,Bulgarian Ship Hydrodynamics Center | Stern F.,University of Iowa
11th International Conference on Fast Sea Transportation, FAST 2011 - Proceedings | Year: 2011

The accurate prediction of waterjet propulsion using CFD is of interest in the standpoint of performance analyses of existing waterjet designs as well as design optimization of new waterjet propulsion systems for high-speed marine vehicles. Currently, the design and analysis of waterjets follow the ITTC '05 recommended procedures and guidelines which was validated by a rigorous experimental campaign through standardized testing. The current study focuses on validation of detailed duct flow simulations on catamarans using the Delft catamaran as the model. The validation work is conducted as a pre-requisite for subsequent URANS based optimization. The Delft catamaran model was build at BSHC and a customized waterjet was designed for the model based on pre-existing stock waterjet designs. Data from the model testing using the ITTC '05 procedures include net jet thrust, thrustdeduction, water-jet volume flow-rate, sinkage, trim, and jet velocity surveys at nozzle exit. Simulations were performed over a speed range of 0.4>Fr>0.75 using URANS and an actuator disk body-force model. The computed net jet thrust, thrust deduction, sinkage and trim compare well with experiments indicating that the present approach is an efficient tool to predict the performance of waterjet propelled JHSS and paves way for future optimization work. © 2011 American Society of Naval Engineers.

Parvanova R.,Bulgarian Ship Hydrodynamics Center
10th International Multidisciplinary Scientific Geoconference and EXPO - Modern Management of Mine Producing, Geology and Environmental Protection, SGEM 2010 | Year: 2010

An analysis of the factors that affect implementation of investment plans for a construction of engineering structures in coastal area is presented. The report attempted to clarify the legislative and administrative problems in the design and implementation of quality investment projects. There are a number of generally valid requirements and prerequisites for projects that directly affect their level of efficiency and effectiveness. There is need a profound analysis of the influence of real political, economic, social and technological environment in which the project is implemented. Secondly, it is necessary to complete self-study and assessment of possible risks to the project implementation. Thirdly, an analytical research and quantitative assessments of the strengths and weaknesses of the project actual potential is needed. Fourthly, it is necessary to comply with certain requirements for technology development, management and project implementation. A subject of the report is to investigate the legislative and administrative difficulties, which negatively affect technology development, management and implementation of projects in those specific geographical regions as coastal areas. As a result of the analysis one variant of optimization procedure for design and implementation of investment designs is offered. © SGEM2010 All Rights Reserved by the International Multidisciplinary Scientific GeoConference SGEM Published by STEF92 Technology Ltd.

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