Towed Cable System Vibration Responses to Varying Towed Velocity

 

WANG Zhibo

（Jiangsu University of Science and Technology, Zhangjiagang, 215600, China)

 

Abstract: Based on a validated numerical calculation model, the vibration responses of a towing system under impact are calculated using the automatic time resolution adjustment algorithm. This paper analyses the influence caused by varying the towline length and weight, the tow speed and the acceleration time on two tension oscillating periods. The results show that the tension in the towline gradually decreases after a short period of oscillation during acceleration; the towing system exhibits excellent linear behavior after obtaining stable kinetic energy input; and the hysteresis of tension steep drop is observed during the termination phase, where the impact tension is significantly larger than the oscillations during the initial stage. If the towed mass is increased, the peak of the impact oscillation increases while the oscillation time remains the same, and the peak of the acceleration termination stage decreases. The shorter the acceleration duration, the stronger the impacts of the two stages are; the longer the acceleration duration, the longer the tension oscillation period will be. Increase of the towline will increase the elastic effect, resulting in significant increase of the impact effect on the towing system.

Key words:towing system; acceleration; vibration

 

 

 

Analysis on the Unsteady Aerodynamics of Floating Wind Turbines

 

LIN Yi^a,b,c，LI Ye^a,b,c，DUANLei^a,b,c

（a. State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean & Civil Engineering;

b. Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration;

c.School of Naval Architecture, Ocean & Civil Engineering,

Shanghai Jiao Tong University (SJTU), Shanghai 200240, China）

 

Abstract: Reduced frequency is applied to the analysis of unsteady aerodynamics and influencing factors of floating wind turbines under different operation conditions. Algorithms with different accuracies are used to calculate the wake fields of a floating wind turbine, in order to predict the aerodynamics of the turbine and to investigate the influence of wake self-induced velocity on its dynamic characteristics. The results show that the time-marching free vortex method has relatively good accuracy; the selection of algorithms has little influence on the dynamic characteristics of the floating wind turbine but has large influence on the geometric stability of the wake trajectories. Compared with the wake fields of stationary wind turbines, the wake fields of floating wind turbine have stronger non-uniformity, and the influence of self-induced velocity on the turbine’s dynamics should not be neglected. 

Key words:floating wind turbine; free vortex; aerodynamics; time-marching

 

 

 

Design of Ship Emission Monitoring and Control System

 

ZHUO Jing¹, HUANG Xiaofeng²

(1. Zhejiang Institute of Mechanical & Electrical Engineering Department of Transportation Technology,

Hangzhou 310053, China;

2. Ship Supervision Department, Hangzhou Maritime Safety Administration, Hangzhou 310053, China)

 

Abstract: A ship emission monitoring and control system is designed to monitor in real time the nitrogen oxide and sulfur oxide in the exhaust gas of ships, and to convert the data into analog numerical signals. One of the signals is transmitted to ship’s Voyage Data Recorder (VDR), where the signal data are stored for follow-up inspections; the other is transmitted to the ship borne Automatic Identification System (AIS) for maritime authorities to receive in real time to determine whether the ship is emitting pollutants. In this way, the maritime authorities can keep the ship under control so as to raise the effectiveness of the supervision.

Key words:ship emission; nitrogen oxides; sulfur oxides; ship borne Automatic Identification System (AIS); ship’s Voyage Data Recorder (VDR)

 

 

 

Power Configuration of Medium and

Small Size Trailing Suction Dredgers

 

YI Hui¹，AN Chao²，QUAN Xianghong¹

(1. Shenzhen Huawei Offshore Shipping Transport Co., Ltd., Shenzhen 518067, China;
2. Merchant Marine College, Shanghai Maritime University, Shanghai 201306, China)

 

Abstract: To solve the problem of low utilization rate, high energy consumption and high operating cost of the small and medium-sized trailing suction dredgers in China, a power configuration scheme for hybrid drag is proposed in terms of ‘one drives three’ and ‘one drives two’ based on the research object of a 6500m³ suction dredger. The power check calculations are carried out under the conditions of navigation, dredging and bank discharging, and the results show that the power configuration can meet the power requirements of all the mechanical equipment on the target ship under various working conditions. This study can provide reference for the optimization of power configuration of domestic small and medium-sized suction dredgers.

Key words:trailing suction dredger; power configuration; hybrid drag

 

 

 

Analysis of Internal Flow in Waste Heat Recovery Turbine

for Marine Diesel Engine

 

SONG Yang¹, PENG Jiewei²

（1. China Shipbuilding Information Center, Beijing 100097, China;

2. Shanghai Marine Diesel Engine Research Institute, Shanghai 200090, China）

 

Abstract: As marine diesel engine plays an irreplaceable role in ship energy saving and emission reduction, this paper proposes to recover the waste heat of marine medium-speed diesel engine by using waste heat recovery turbine. The numerical simulation method is used to analyze the internal flow of the power turbine to provide reference for the design optimization and application of waste heat recovery turbine. The turbine flow field numerical simulation shows that the overall flow of the volute and the impeller is good, but there is a large angle of attack at the entrance of the rotor blade as well as a small range of flow separation. In addition, vortex inevitably occurs in some rotor paths under the influence of the relative motion between rotor and stator, which leads to the increase of pressure and temperature and the decrease of flow velocity. Optimization of the impeller blade shape based on the numerical simulation results will help further improve the internal flow and the efficiency of the waste heat recovery turbine.

Key words:diesel engine; waste heat recovery; centripetal turbine; numerical simulation; flow analysis

 

 

 

Marine Winch Cable Arrangement System Based on Fuzzy PID Control

 

HUANG Liangpei^a,b, CHANG Jinjie^a, ZOU Dongsheng^a, KOU Yu^a

(a. Hunan Provincial Key Laboratory of Health Maintenance for Mechanical Equipment，

Hunan University of Science and Technology, Xiangtan 411201, China；

b. Advanced Mineral Equipment Research Centre under the Ministry of Education，

Hunan University of Science and Technology, Xiangtan 411201, China)

 

Abstract: The sophisticated operating condition of marine winches makes the cable arrangement control system susceptible to the unpredictable factors such as load disturbances and variation of system parameters, and the poor anti-jamming capability and low cable arrangement accuracy of the conventional PID (Proportion-Integral-Derivative) controller also affect the operation. Therefore, this study proposes a winch cable arrangement system based on fuzzy PID control. The working mechanism of the marine winch cable arrangement system is theoretically analyzed, the fuzzy control algorithm is elaborated and a fuzzy PID controller is designed. Then, a winch cable arrangement system model is established in Matlab/simulink based on vector control and SVPWM modulation principle, which was simulated and compared with the conventional PID control system. The simulation results show that the system designed has the advantages of fast response, small overshoot and strong anti-interference ability. It can satisfy the performance requirements of the winch cable arrangement control system.

Key words:marine winch; cable arrangement system; fuzzy control

 

 

 

Functional Design of Liquid Cargo Monitoring for

Very Large Liquified Petroleum Gas Carrier

 

YANG Sen, YANG Jun, FAN Fan

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

 

Abstract: With an 85000m³ Very Large Liquefied Petroleum Gas Carrier (VLGC) as the research object, this paper analyzes the fundamental architecture, equipment configuration, interface connection, operating mode, function setting and other necessary ancillary systems for the liquid cargo monitoring system based on the cargo characteristics, design conditions and operating requirements for cargo handling and carriage. Considering ship operation safety, it explains in compliance with the rules of Classification Societies, the international regulations and the guidelines of some organizations, and implements these rules and regulations in the design practice. Overseas’ design concepts and foreign user’s experience are taken as reference, the functional design essentials for the liquid cargo monitoring system are elaborated, which provides the theoretical basis to promote the hardware and software design of liquid cargo monitoring system, so as to promote the realization of system localization.

Key words: liquefied petroleum gas carrier (LPGC); liquid cargo monitoring; functional design; operating mode; emergency shutdown (ESD)

 

 

 

Influence of SOLAS 2020 on the Design of Ro-Pax Ships

 

LI Hongwei¹, WANG Dong², ZHENG Hongyu³

(1. Huanghai Shipbuilding Co., Ltd., Weihai 264309, China;

2. Shanghai Merchant Ship Design and Research Institute, Shanghai 201203, China;

3. Marine Design and Research Institute of China, Shanghai 200011, China)

 

Abstract: Compared with the previous version, the newly modified SOLAS 2020 regulation stipulates higher requirements on the damage stability of passenger ships including Ro-Pax ships. Calculation shows that most of the existing Ro-Pax ship designs cannot comply with the requirements, so they are in demand of optimization and upgrading. This paper puts forward five technical solutions based on three sample Ro-Pax ships, i.e. increasing the value of initial metacentric height, increasing the height of weather-tight openings, increasing molded depth, increasing the number of subdivisions and increasing the width of the beam. Evaluation of the performance of these schemes in improving ship’s damage stability and their comprehensive influence on ship design and operation leads to some useful comments and methods to comply with the new regulation, which could be reference for relevant practitioners.

Key words:SOLAS 2020 regulation; Ro-Pax ships; damage stability; subdivision index

 

 

 

Analysis on the Key Technologies of Welding Robots

in Shipbuilding Industry

 

YU Jun, WANG Yuze, LI Chao, ZHAO Jiawen

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

 

Abstract: In order to sum up the experience accumulated from the intelligent welding system project by Shanghai Waigaoqiao Shipbuilding Co., Ltd., two welding robot systems are compared with each other to find out the differences in debugging and operation. The emphasis is laid on the analysis of model information collection technology, selection of welding paths and welding torch postures, welding techniques and integration of production lines. The result shows that the sub-assembly robot with the mode of “field collection + automatic identification” performs better than the other with the mode of “3D model importation + off-line programming”. This study is helpful to make good technical reserves for the promotion of subsequent intelligent manufacturing projects.

Key words:application of welding robot; intelligent welding ststem; model information; sub-assembly production line

 

 

 

L2P Association Design Technology for Piping System

Based on 3DEXP

 

LI Ji, ZHU Minghua, YANG Yigan, TANG Neng

(Jiangnan Shipyard (Group) Co., Ltd., Shanghai 201913, China)

 

Abstract: To solve the problems caused by separated detail design and production design of marine piping systems, such as non-unified design data source, low efficiency of manual information conversion, difficulty in model and principle checking and inconsistency of design modifications, this paper proposes a solution of Logical to Physical (L2P) association design technology based on 3D Experience Platform (3DEXP). L2P association design technology is a design paradigm innovation of marine piping systems, which binds the logical objects closely with the physical objects. This study analyzes the reasons behind the problems under the existing design paradigm, and investigates the design procedures, design preparations, principle drawings and 3D modeling based on the principle drawings of the L2P association design, so as to achieve rapid 3D modeling, intelligent model check, consistent design modification and united data source. The application result shows that the L2P association design technology for piping systems can effectively increase design efficiency and design quality of the piping system.

Key words:3D Experience Platform (3DEXP); Logical to Physical (L2P); association design

 

 

 

Large Offshore Platform Assembly Technology

Based on Three-Dimensional Visualization

 

GUO Liang¹, JIA Tao¹, QIU Chengguo¹, TIAN Dafei¹, SUN Xintao¹, NAN Fuzheng²

(1. Technology Center, TZ (Tianjin) Binhai Heavy Machinery Co., Ltd., Tianjin 300457, China;

2. YanTai CIMC-Raffles Offshore Co., Ltd., Yantai 264000, China)

 

Abstract: In order to provide a digital solution for the design and construction of offshore platform, this paper studies the key factors of the organization framework, the input, processing and distribution of information based on the three-dimensional assembly system, and proposes some practical specifications which provide theoretical guidance for the digital design and construction of large offshore platforms.

Key words:hull blocks; assembly technology; virtual assembly; collaborative design; three-dimensional simulation; assembly path planning; model light weight

 

 

 

Analysis on the Establishment of Emergency Rescue System for Deepwater Submarine Pipeline

 

WANG Zhe

(Offshore Oil Engineering Co., Ltd., Tianjin 300461, China)

 

Abstract: This paper analyzes the shortcomings of the current emergency rescue system, and gives some suggestions for the construction of the emergency rescue system. The technical analysis and economic evaluation of the technical plan shows that the deepwater submarine pipeline emergency rescue system is the key facility to respond to emergencies and should be invested as part of the national strategic emergency plan. The paper suggests setting up an emergency rescue team on the basis of the emergency rescue team of the CNOOC Engineering Pipeline in the mode of investment by enterprises and appropriate subsidies by the state. When the complete deepwater submarine pipeline emergency rescue system is established, the emergency response mechanisms should be improved, the information standards should be unified, and all the resources should be shared. The submarine pipeline emergency rescue system with a working capacity under 2000m water depth should be established to realize the full coverage of emergency repair of the submarine pipeline for the development of deepwater oil and gas fields in the South China Sea. At the same time, the system should play a major role in the offshore engineering construction and has a good economic return.

 

Key words:deepwater submarine pipeline; emergency rescue; repair