Analysis on the Characteristics of Bubble Group Motion

Inside Bubble Pump Riser

 

LIU Bing-bing¹，WANG Ming-yu¹，GAO Hong-tao²，ZHANG Shao-jun¹

（1. College of Naval Architecture and Marine Engineering, Shandong Jiaotong University, Weihai264310, China;

2. Institute of Marine Engineering, Dalian Maritime University, Dalian 116026, China）

 

Abstract: In order to study the working mechanism of lithium bromide bubble pump, two-phase flow lattice Boltzmann free energy model with Inamuro’s large density ratio is taken as the basis where the space neighboring points are replaced by time neighboring points, and the parametrically controlled difference terms are introduced into the phase transitional distribution function f_i. The second order upwind difference scheme is used to solve the first order partial terms and the fourteen points central difference scheme is to solve the second order partial terms. Then the simulated two-phase flow density ratio of the enhanced model is increased from 1000 to 3000 for the first time, expanding and improving the adaptability of the lattice Boltzmann method to simulate the large density ratio multi-flow problems. Through simulating the parallel bubbles rising and coalescing in the lithium bromide inside the vertical pipe of the bubble pump with a gas-liquid density ratio of 2778, the bubbles’ density field and velocity vector distribution diagram under different initial conditions are obtained, and the motion patterns of the bubbles are analyzed and summarized. The result shows that the mutual attraction and repelling interactions in between the bubbles are related to the size and initial position of the bubbles in the bubble group. The critical distance of the coalesced bubbles decreases when the diameter or quantity of bubbles increases.

Key words:lattice Boltzmann method; bubble group; motion process

 

 

 

Progress of the Research on Unloading System for LNG Floating Production Storage and Offloading Unit

 

YANG Liang¹，LIU Miao-er¹，LIU Yun²，XU Jia-wei¹

（1. Research and Development Center, CNOOC Gas & Power Group Co., Ltd., Beijing 100028, China；

2. CNOOC Research Institute Co., Ltd., Beijing 100028, China）

 

Abstract: Liquefied Natural Gas(LNG) floating production storage and offloading unit is an effective facility in the development of marginal gas field, where specially designed unloading systems are especially essential for offshore LNG transportation to meet the strict regulations regarding low temperature and sway conditions. Two types of unloading systems are introduced with emphasis on the structure and parameters of cryogenic flexible hose, which demonstrates the comprehensive advantages in terms of flexibility, corrosion resistance, thermal insulation and etc. It comes into the conclusion that side-by-side unloading system is suitable for offshore LNG transportation in the calm sea, while the tandem unloading system is more suitable for deep-sea LNG transportation in the rough sea. It also indicates that the cryogenic flexible hose has a cheerful prospect in the field of offshore LNG transportation.

Key words:LNG; unloading arm; cryogenic flexible hose; side-by-side offloading; tandem offloading

 

 

 

Structural Design and Strength Check of Bolted Connection of On-site Assembled Sightseeing Boat

 

ZHANG Xiao-ying，HU Zhe，LIN Guo-zhen，ZHU Zhao-yi，CHEN Qing-lin

（Key Laboratory of Ships and Ocean Engineering of Fujian Province, Jimei University, Xiamen 361021,China）

 

Abstract: Assembling sightseeing boat on-site is a good way to solve the problem of transportation from shipyard to scenic area and reduce cost. This means the hull segments are manufactured in the shipyard and then transported to the scenic area for assembly, which effectively simplifies the procedure of delivery. In order to ensure the operability of assembly and the safety of hull structure, the design and strength check of the structures are of vital importance. The bolted connection is designed for the main hull and the crossing structures, and the finite element method is used for the strength check of the bolted connection structures. The result shows that the structures designed in this way can meet the strength requirements.

Key words:on-site assembled sightseeing boat; bolted connection; structure design; strength check

 

 

 

Design and Analysis on the Hydraulic System of

A- Type Frame Crane

 

DING Hai-dong，LI Da-ping，ZHANG Yuan

（Shanghai Zhenhua Heavy Industries Company Limited, Shanghai 200125, China）

 

Abstract: A-type frame crane is taken as the research target, of which the mechanical structure and hydraulic system are designed and analyzed, where the influence of cleanliness and temperature of oil on the system and the influence of air content of hydraulic oil on the bulk modulus are analyzed, and the importance of hydraulic exhaust on A-type frame crane is studied. As PID control is introduced to the luffing mechanism, excellent performance has been achieved based on simulations.

Key words:launch and recovery; hydraulic system; bulk modulus; position control

 

 

 

Influence of Elastic Support Simplification on the Calculation of Ship End-Launching Load

 

ZHOU Yan-qiu，MEI Yong-juan

（China Ship Development and Design Center Shanghai Branch，Shanghai 201108, China）

 

Abstract: End-launching is currently the most common method for ship launching, but it requires calculation beforehand. Finite element software ANSYS is used to calculate the launching bending moment for the mechanical analysis of the launching process so as to provide accurate input to check the hull strength. Meanwhile, the influence of support stiffness coefficient and support quantity upon the launching bending moment is discussed. This study provides some suggestions for practical calculations.

Key words:end launching; elastic support; finite element method; software ANSYS

 

 

 

Innovation and Application of

Power System Integration Technology on Green Ships

 

ZHAO Tong-bin, LIU Zhang-chao, LI Ce-lue, GUO Feng-ze, TAN Kun, LIU Liang-qing

(Shanghai Marine Diesel Engine Research Institute, Shanghai 201108, China)

 

Abstract: This paper analyzes the development trend of greener and more integrated marine power systems, and points out the advantages and necessity of green power system integration. It elaborates the domestic technique innovation ofpower integration with the focus on the diesel-electric hybrid power system, variable speed power generation and DC network electric propulsion power, low noise power and the diesel engine utilizing total energy. It also explains the   applications of the technology on full scale ships and looks into the future development of green power systems, which provides references for the green power system integration and innovation in China.

Key words:ship; green power system; power system integration

 

 

 

Analysis and Solution for Large Pressure Fluctuation of the Fuel inletting Main Engine on a Ship

 

CHEN Yan-fei, CHEN Meng, XIAO Chao

(Shanghai Jiangnan-Changxing Shipbuilding Co., Ltd., Shanghai 201913, China)

 

Abstract: This study aims to solve the problem of large pressure fluctuation occurred when the fuel comes into the main engine in the sea trial of a ship. A solution has been proposed after a thorough analysis of the components, including the fuel supply unit, the main engine, the fuel piping system, kinds of energy accumulators and so on. It may provide useful information for shipyards, ship owners, classification societies and professionals.

Key words:main engine; fuel pressure fluctuation; fuel system

 

 

 

Application of Detection and Control Technology to

Subsea Multiphase Transport Booster Pump

 

SHEN Dan, WANG Lei, ZHENG Peng, HAN Jun

(China ship Scientific Research Center, Wuxi 214082, China)

 

Abstract: Technical schemes of the underwater sensor detection, the control of multiphase transportation pump and motor, and the control of subsea valve are proposed in this paper for the 1500m subsea oil-gas transport booster pump system. The rationality, reliability and stability of the whole detection and control system are verified in the experiments. The research provides a technical basis for the design of detection and control system and for the development of subsea multi-phase transport booster pump.

Key words:oil and gas field development; subsea multi-phase transpora booster pump; underwater detection technology; motor speed control; valve control

 

 

 

Electric Propulsion System Design for

Ocean Fishery Resources Survey Vessels

 

LIU Xiao-qing

（China Ship Development and Design Center Shanghai LingYao Marine Engineering Co., Ltd., Shanghai 201108, China）

 

Abstract: This study makes a comprehensive analysis on the electric propulsion system of a fishery resources survey vessel designed and built in China, which covers the typical working conditions of fishery survey, the operation condition of power station and the harmonic control in the sea trial. The functions of the vessel’s power station management system are also introduced in detail.

Key words:ocean fishery resource survey vessel; electric propulsion system; power station management system; Voith Schneider propeller

 

 

 

Study on the Diesel Engine NO_x Emission Modeling

Based on ELM Theory

 

LIN Hong-gui^1,2,3，LIN Jin-biao^1,2，YU Hong-liang^1,2,3

（1. Marine Engineering College, Jimei University, Xiamen 361021, China；

2. Provincial Key Laboratory of Naval Architecture & Ocean Engineering, Xiamen 361021, China；

3. Fujian Engineering Research Center of Marine Engine Detecting and Remanufacturing, Xiamen 361021, China）

 

Abstract: Diesel engine system is complicated and changeable. There is not a clear and accurate relation between its input and output. In order to accurately predict the emission of diesel engines, an optimized neural network with Extreme Learning Machine (ELM) theory is adopted to model the emission, working load and fuel injection advance angle, and thus to find the process control approaches for diesel engine performance optimization.

Key words:Extreme Learning Machine (ELM); diesel engine emission; modeling

 

 

 

Discussion on the Welding Technology of

ZG230-450C Stern Shaft Bracket

 

SHAO Yong¹，CHEN Ai-guo²

（1. CSC Shenzhen Ship Management Co., Ltd., Shenzhen 518054, China;

(2. School of ship Engineering, Guangzhou Maritime university, Guangzhou 510725, China）

 

Abstract: To solve the problems of lamellar tearing and large deformation in welding of the stern shaft bracket made of ZG230-450C cast steel on a ship, an approval test of the welding technology is developed, where CO₂ semi-automatic flat angle welding is used with DC reverse connection method, T-type tie-in, TWE-711 welding thread and U-type opening slope. The welding course and order are properly arranged and suitable process parameters are reasonably set. Two welders simultaneously carried out the welding operation in opposite directions, strictly complying with the welding process and thermal treatment principles. Meanwhile, stern shaft bracket is rigidly fixed to ensure welding quality, and to control and rectify welding deformation.

Key words:ZG230-450C cast steel; welding; welding deformation

 

 

 

 

YANG Li-zhi, LIU Kai

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

 

Abstract: The stern structure deformation of a twin-skeg Liquefied Natural Gas (LNG) carrier in the erection stage is studied to obtain the deformation pattern of stern structure and its extent under common conditions, so as to provide the basis for the inverse deformation added. The comparison of the finite element analysis result with the measurement result is used to make the theoretical method combined with practice and thus to realize the prediction of deformation and its extent at the stern part of the twin-skeg LNG carrier. The result shows that the overall deformation of the stern structure is sinking along the z axis, and the accumulated deformation can reach up to -24.1mm/-17.9mm (shaft/rudder). It is suggested that +10mm inverse deformation should be placed if the single blocks of the EBZ01 engine room are lifted separately, while +15mm inverse deformation should be placed if the block is lift as a whole in the erection stage.

Key words:LNG carrier; deformation of the stern structure; finite element analysis

 

 

 

Research and Development of the On-Line

Safety Monitoring System for Engineering Ships

 

LIU Guo-sheng，TAO Ming，WANG Xiao-feng，LIU Lie-hui，YUAN Zi-hao

（CCCC Guangzhou Dredging Co., Ltd., Guangzhou 510300, China）

 

Abstract: In order to ensure and enhance the supervision over the safe production of engineering vessels and to raise the equipment intact rate while providing advanced technical supports such as long-term accident pre-warning and remote online fault diagnosis for the enterprises, the “safety status online monitoring system for engineering ship” has been developed. The system is based on the online sharing of the on-site ship operational data and synthetically integrates the mature industrial technologies such as modern sensors, automation and instrumentation, network communication and computers, and consists of shore-based central monitoring server, wireless mobile network and system communication protocol, intelligent ship operational data collecting system and etc. The shore-based central monitoring server can track all of the engineering ships through the mobile communication network and find every potential abnormal incident in time. The result shows that the system plays an excellent role in monitoring’safe production of the ship, the machinery equipment and the on-site construction.

Key words:dredging construction; sensors; wireless communication chain; online fault diagnosis; Geographical Information System (GIS)