Research and Application of Ship¢s Bubble Drag Reduction Technologies at Home and Abroad

 

HU Yi-huai, LI Hui-jing, HE Hao

（Merchant Marine College, Shanghai Maritime University, Shanghai 201306, China）

 

Abstract: This paper introduces the domestic and foreign research work on ship bubble drag reduction technologies, including experimental and numerical calculation results related to micro-bubble drag reduction, bubble curtain drag reduction and air film drag reduction. Special attention has been paid to the inclined plate bubble drag reduction technology developed in Russia, the micro-bubble drug reduction technology developed in Japan and the thin air film drag reduction technology developed in China. Meanwhile, both domestic and overseas mechanical models, numerical calculation methods and important conclusions are introduced. The applications of bubble drag reduction technologies on board ships since the 1960s are reviewed, especially the performance and the energy saving effect of those ships using bubble drag reduction designed by Russia, Japan and Denmark. In view of the present situation of the application of the bubble drag reduction energy saving technology in our country, this paper analyzes the existing problems and shortcomings, and discusses the application prospects of the ship's bubble drag reduction technology in our country.

Key words:micro-bubble drag reduction; air film drag reduction; bubble curtain drag reduction; ship energy saving

 

 

 

Finite Element Calculation and Analysis of Asphalt Carrier¢s Structural Strength Taking into Account the Temperature Load

 

CHEN Di-yi, WANG Wei, XIE Yong-he, LU Xin

（Naval Architecture and Electromechanical Engineering College, Zhejiang Ocean University, Zhoushan 316022, China）

 

Abstract: The influence of excessive high temperature on the asphalt carrier’s hull structure cannot be neglected, during its transportation of high temperature asphalt. For this, taking the 6600DWT asphalt carrier as the example, the MSC/PATRAN and MSC/NASTRAN software are used to perform the finite element calculations on the asphalt carrier’s structural strength, while taking into account the temperature load. The influence of temperature field load on the asphalt carrier’s structural strength is analyzed, and proper strengthening schemes are proposed for those structures which do not meet the strength requirements.

Key words:asphalt carrier; temperature load; finite element; structural strength

 

 

 

Design of a Shipborne Police Flight System with

Target Identification Function

 

HE Xue-ming

（Department of Electrical and Mechanical Management, China Maritime Police Academy, Ningbo 315801, China）

 

Abstract: A shipborne police flight system is designed to enable the maritime police force to fast identify suspicious vessels from numerous ships and to fast obtain the detailed information of the suspicious vessel during law enforcement at sea. This system can achieve low altitude scout and gather images of the suspicious object through the shipborne target identification system, and is equipped with powerful suspicious object database for the fast and accurate identification of objects at sea. The experimental result shows that the proposed method and the design will fully satisfies the requirements of the maritime police force, the designed flight system is suitable for ship-borne and police purpose, and the designed target identification system is accurate, reliable and has high value for wider application.

Key words:target identification; ship-borne; police; aircraft; design

 

 

 

Technical Study on the Membrane Type Storage Tanks

of LNG Receiving Station

 

SONG Zhong-bing，XU An-nan，LIU Heng

（Hudong-Zhonghua Shipbuilding (Group) Co., Ltd., Shanghai 200129, China）

 

Abstract: The technologies of the storage tank for Liquefied Natural Gas (LNG) receiving station not only determines the size of the station, but also directly influences its construction period and investment cost. This paper summarizes the structure, material and capacity of the membrane type storage tanks for LNG receiving stations, and compares the advantages and disadvantages of different technologies. As a result it is found though the study that the membrane type storage tanks have the characteristics of large volume, small footprint, short construction period and low construction cost. It is the first choice for building LNG storage tanks of receiving stations in the future.

Key words:LNG receiving station storage tank; 9 nickel steel type; membrane type

 

 

 

Research on the Nonlinear Finite Element Method for

Ultimate Strength of Ship Hulls

 

WU You-jun，WAN Qi，ZHOU Bo

（Marine Design & Research Institute of China, Shanghai 200011, China）

 

Abstract: The ultimate strength of ship hulls is one of the important factors for ship vitality, the requirements on which are clearly specified in the rules and regulations of classification societies around the world. Taking a double hull oil tanker as the research object, the nonlinear finite element method is adopted to calculate its ultimate strength. Finite element calculations on the same object are performed with different gird sizes, boundary conditions, loading modes and with or without lateral loads. The calculation results are compared and analyzed to propose the proper grid size, boundary condition configuration and loading mode, and to obtain the advantages and disadvantages of whether or not to apply the lateral loads. This study can provide some reference for the hull structure ultimate strength calculations using nonlinear finite element method.

Key words:nonlinear finite element; ultimate strength; hull structure

 

Deck Arrangement of Small-and Medium-Size LNG Carrier with Type C Independent Tank

 

ZHOU Wei

(COSCO Dalian Shipyard, Dalian 116113, China)

 

Abstract: TakingQI YUAN, a 28000m³ Liquefied Natural Gas carrier (LNG) with C type independent liquid cargo tanks, as the research object, this paper analyzes in detail the deck arrangement, including the mooring arrangement, tank DOME arrangement, manifold area arrangement, ship to ship transferring arrangement and etc. The arrangement rationality of each system and the feasibility of design optimization are studied.

Key words:type C independent tank; LNG carrier; deck arrangement

 

 

 

Analysis on the Vapor Return Compressor Operating Point

of Large LNG Carriers

 

LIU Tao，CEN Zhuo-lun，XU An-nan

(Hudong-Zhonghua Shipbuilding (Group) Co., Ltd., Shanghai 200129, China)

 

Abstract: Based on the operation and design parameters of a large Liquefied Natural Gas (LNG) carrier, the state equation method is used to study the physical parameters of the gas-liquid natural gas and the inert gas. The load required for the Vapor Return Compressor (VRC) to treat the process gas during cargo loading is analyzed so as to determine its maximum treatment capacity. Then the operating points of the VRC under different technological process are analyzed according to the process design of gas displacement and the initial cooling and heating-up of cargo tank. The establishment of the operating points can provide the basic technical specification requirements for the design of VRC of large LNG carriers.

Key words:large LNG carrier; vapor; vapor return compressor; operating point

 

 

 

Exploration of a New Type of Energy-Saving Device for Ships

—Door-Type Bow Thruster Cover

 

WU An，WANG Zhong-qiang，KONG Ming-min

（Hudong-Zhonghua Shipbuilding (Group) Co., Ltd., Shanghai 200129, China）

 

Abstract: This paper introduces the application and the exploration of a new type of ship energy saving device—the door-type bow thruster cover equipment. From the conventionally used gratings that extend from the bow thruster tunnel at two ends to the external cover plates, the design is continuously optimized and explored. And eventually is found the door type bow thruster cover device that will not only save energy for ships but also operate conveniently.

Key words:energy saving;ship; door-type bow thruster cover

 

 

 

Selection and Application of Main Body Material for the Independent Type C Cargo Tank of Liquefied Gas Carrier

 

ZHANG Zhao-hua^1,2,3，FENG Da-cheng^1,2,3，HUA Xue-ming^1,2

（1. Shanghai Key Laboratory of Laser Manufacturing and Material Modification, Shanghai Jiao Tong University,

Shanghai 200240, China；2. Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration Equipment,

Shanghai 200240, China；3. CRYOLOBE Gas Technology Co., Ltd., Shanghai 200441, China）

 

Abstract: This paper introduces the definition and categorization of type C Cargo tanks. According to the type and liquefaction method of the liquid cargo, the minimum design temperature can be determined, whereby the materials for the main body of the tank are selected. Four typical types of main body material are listed, and their unique application performance and quality requirements in engineering applications are elaborated.

Key words:liquefied gas carrier; independent type C Cargo tank; material

 

 

 

Study on the Overall Design of the Robot Production Line for Sub Assembly

 

JI Yong-jun^1,2，ZHU Yu-long²，LIU Jian-feng²

（1. Naval Architecture and Ocean Engineering College,Jiangsu University of Science and Technology, Zhenjiang 212003, China;

2. Shanghai Waigaoqiao Shipbuilding Co., Ltd., Shanghai 200137, China）

 

Abstract: Based on the production program of typical sub assembly, this paper analyzes the processing technology of sub assembly, sets up the detailed processing route and studies the overall layout design of work stations of the robot production line for sub assembly. According to the production program of typical work pieces, design studies on the welding robot workstations are carried out from two aspects, i.e., the equipment composition and the system integrated control. Meanwhile, based on the five aspects of cycle time, number of workers, product quality, production continuity and production management, the comparisons between robot  production line and the conventional production scheme for sub assembly are made. The result shows that compared with the conventional sub assembly production scheme, the robot welding production line has higher production rate, requires fewer people, has more stable and more excellent product quality, and has the characteristics of good production continuity and more intelligent production management, therefore can achieve the goal of higher production efficiency, reducing number of workers, improving welding quality, and enabling the realization of intelligent manufacturing of large scale, high efficiency and batch production of the sub assembly work pieces.

Key words:robot production line for sub assembly; process analysis; overall design; effect evaluation

 

 

 

Analysis on the Key Technologies of Sub Assembly

Intelligent Production Line

 

ZHAO De-xin^1,2，ZHU Yu-long²，LIU Jian-feng²

（1. Jiangsu University of Science and Technology, Zhenjiang 212000, China;

2. Shanghai Waigaoqiao Shipbuilding Co., Ltd., Shanghai 200137, China）

 

Abstract: This paper studies the sub assembly intelligent production line at home and abroad, and analyzes its key technologies such as early stage design of the production process and the production line control system. The sub assembly model import and date conversion are analyzed based on off-line programming, and the analysis of welding process parameters provides important data support for the welding process library. On the basis of robot sensing technology, work piece positioning, seam tracking and other technical questions are discussed. The feasibility of the production line established in this way is verified by simulation, which is referential for the establishment of sub assembly intelligent production line.

Key words:sub assembly; off-line programming; welding process library

 

 

 

Research on the Application of Floating Floor in a Cabin

 

SHANG Zhao-yang，ZHANG Yu-li，XIAO Jian

（Hudong-Zhonghua Shipbuilding (Group) Co., Ltd., Shanghai 200129, China）

 

Abstract: In view of the fact that structural form adjustment and application of damping coatings can barely solve the vibration and noise issues in a ship cabin, this study tries to lower the vibration and noise by means of marine floating floor. The five aspects including the principles, composition, work process, testing plan and test results of the floating floor are elaborated and analyzed in this paper, and the effect of the floor in terms of vibration and noise reduction is checked. After the the float floor is installed, the vibration and noise condition are significantly improved according to the measurements by special instrument, which can provide some guidance and reference for the vibration and noise reduction in other cabins.

Key words:floating floor; accommodation cabin; application research

 

 

 

Noise Analysis & Control in VLCC Superstructure

 

ZHANG Ming^1,2, CHEN Hui-qin², CHEN Hong², ZHAO Jing-de¹

（1. College of Environmental Science and Engineering, Donghua University, Shanghai 201620, China；

2. Shanghai Waigaoqiao Shipbuilding Co., Ltd., Shanghai 200137, China）

 

Abstract: Based on the new requirements on noise limits at different locations on board the ship according to the Code on Noise Levels on Board Ships, adopted by the Resolution of MSC.337(91), this paper carries out a general systematic analysis on ship noises from three aspects including the noise source, the noise transmission route and the recipients, so as to propose the key research directions for ship noise reduction design. Considering the noise measurement data of a series of Very Large Crude-oil Carriers (VLCCs) at some typical locations during sea trial both before and after design optimization, the reasons behind excessive noises at certain locations are analyzed, and some corresponding noise control measures are proposed, along with some suggestions for more effective ship noise control in the future.

Key words:noise; analysis; control

 

 

 

Fast Generation of Local Fine Mesh

for Finite Element Structure Model

 

ZHANG Zhi-kang^1,2，HAN Yu²，LIN Yan¹，CHEN Bin²，TANG Yu²

（1. Dalian University of Technology, Dalian 116024, China;

2. Marine Design & Research Institute of China, Shanghai 200011, China)

 

Abstract: Direct calculation is usually used for the structure strength analysis in ship structure design and a sub-model with fine mesh is necessary for the calculation of critical stress concentration areas. Considering the fact that the modeling process is time-consuming and it severely affects the design efficiency, this study proposes a fast local fine mesh generation method for the finite element structure model. The method is based on the idea of “generating finite element mesh geometrically and adding auxiliary hard lines to guarantee mesh quality”. Taking the advantage of customized development function of Catia and Femap, a reliable and useful code has been developed with Visual Basic language, which significantly improves the efficiency of modeling. The reliability and speed of the code is validated in the modeling of hatch corner for some container ships.

Key words:fine mesh; Catia; Femap; customized development