Table of Content

25 February 2022, Volume 33 Issue 04

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Modeling Analysis of Key Friction Pairs in Low-speed Marine Diesel Engines and Verification of Friction Force Based on Wireless Measurement

LI Rui, MENG Xianghui, XIE Youbai

2022, 33(04):  380-387，396.  DOI: 10.3969/j.issn.1004-132X.2022.04.001

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Tribological properties of low-speed marine diesel engines possessed an important impact on the economy， safety， and stability of ship operations. However， there were few theoretical and experimental studies on the tribology of the engines. The modeling of key friction pairs were realized， and the friction was verified by wireless measurement herein. Firstly， combined with multi-body dynamics and mixed lubrication theory， the tribo-dynamics model of key friction pairs was established. Then， a wireless measurement method of friction force was proposed based on the idea of indirect measurement， and a measurement system was developed to realize the on-line measurement of friction forces under fired conditions. The results show that the simulation results of the friction are consistent with the experimental ones， and the maximum friction errors between the simulation and the experiments are less than 5%. The simulation load of the crosshead bearing is also in good agreement with the experimental load. In addition， for the system oil consumption of the stuffing box， the errors between simulation results and test ones are less than 3%. The results show that the modeling and measurement methods are feasible， and may provide support for tribological design， energy conservation and emission reduction of low-speed marine diesel engines. 

Research on Mode Switching Control Strategy of Marine Diesel/Natural Gas Dual Fuel Engines

SONG Enzhe, JIANG Zhongzhou, YAO Chong, ZHAO Guofeng

2022, 33(04):  388-396.  DOI: 10.3969/j.issn.1004-132X.2022.04.002

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In the actual operations of marine diesel/natural gas dual-fuel engines， switching between pure diesel mode and dual-fuel mode might easily cause large engine speed fluctuations and unstable operations， which endanger the normal operations of the engines. In addition， in some emergencies（such as insufficient natural gas fuel， sudden load unloading， et al）， the engine needed to switch between different modes quickly and smoothly. In response to the demands， a rule-based dual-fuel engine mode switching control strategy was designed based on the operating requirements and mechanism of the dual-fuel engine under the premise of the same control system hardware. Among them， the diesel-to-dual-fuel mode adopted the reverse control method， and the dual-fuel-to-diesel mode was divided into active switching and passive switching to respond to different control requirements. The designed switching control strategy realized the mutual switching of different fuel modes based on experimental calibration data and software algorithms. Finally， an experimental platform was built to verify different operating conditions mode switching control performance based on the YC6K dual-fuel engine. The results show that the designed switching strategy satisfies the switching control requirements under various working conditions， and improves the running performance of the whole machine. 

Study on Tribological Characteristics of Rotary Vane Steering Gear Seals under Different Abrasive Particle Sizes

XIANG Jingjing, DONG Conglin, BAI Xiuqin, TANG Min

2022, 33(04):  397-405.  DOI: 10.3969/j.issn.1004-132X.2022.04.003

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The ship rotary vane steering gears gradually replaced traditional plunger steering gears due to the small size and high power density. However， the wear particles generated during the friction processes often caused abnormal wear of the seals of rotary vanes， which caused seal failure and drop hydraulic oil pressure， and resulted in losing of the function of rotary vane steering gears. Clarifying the friction and wear mechanism between the vane seals and the cylinder and extracting their key wear characteristics were the keys to extend the service life and to realize intelligent fault diagnosis of the rotary vane steering gears. The polyurethane materials which commonly used to make seals were chosen as the research object to study the wear behaviors under different wear conditions. The results show that the characteristic values of friction coefficient， wear volume， wear morphology and vibration signals between polyurethane polymer and carbon steel ball gradually increase with the increase of iron particles size under hydraulic oil-lubricated， which indicates that the wear state is gradually worsening. It may provide an effective way for evaluating or predicting the wear state or failure modes of rotary vane steering gear seals by sensing tribological information， including the friction coefficient， abrasive particles size in the hydraulic oil， wear morphology， wear volume， vibration signals and other characteristics. This study may provide a theoretical basis for revealing the friction and wear mechanism of ship rotary vane steering gear seals， and provide a reference for realizing their intelligent monitoring and fault diagnosis. 

Hydrodynamics Design and Tests of Clearance Flow in Bearings of  Shaftless Pump-jet Thrusters

HE Shengyang, ZHOU Feng

2022, 33(04):  406-412.  DOI: 10.3969/j.issn.1004-132X.2022.04.004

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This paper aimed at the SPT open water self-lubricating structure of the support/thrust integrated water-lubricated bearings with hub layout type. According to the high-speed and high-pressure flow generated by the blades， the water-lubricated bearing lubrication and cooling flow channels were designed thus forming an integrated self-circulating lubrication scheme of support/thrust bearings. Due to the coupling effectiveness of blade hydrodynamics and bearing clearance flow， an iterative design method of bearing clearance flow was proposed. Then a hydrodynamics coupling calculation model for the clearance between the blade and the bearing was established， and the quantitative calculation and analysis of the bearing clearance flow of the SPT was realized. In addition， the open water test of the SPT and bench test of the integrated water-lubricated bearing were completed. In the entire test interval， the maximum error between the calculated values and test results of the thrust coefficient and the bearing clearance flow rate are as 6.2% and 4.6% respectively， which verifiy the effectiveness and accuracy of the design method and calculation model. The proposed methods have important engineering significance for the design and optimization of the SPT. 

Novel NFTSM Control for Servo Systems

SHI Difen, HOU Runmin, GU Xiaohui, HOU Yuanlong

2022, 33(04):  413-420.  DOI: 10.3969/j.issn.1004-132X.2022.04.005

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The shipborne servo system featured friction and intricate disturbances， which needed to improve control precision and robustness. A NFTSM control method was proposed with phase compensation（NFTSM+ARBF+TTD）. Taylors formula-based tracking differentiator（TTD）was innovated with Taylors formula and nonlinear function fhan. The proposed method could compensate phase delay and acquire desired control command， also suppress noises. By using ARBF to approach the disturbance， the chattering problem in NFTSM could be solved effectively. Experimental results show that adaptive radial basis function（ARBF） may suppress the differential peaks and estimate disturbance accurately and effectively. Semi-physical simulation experiments were conducted to tracking sinusoidal reference. The results show that compared with traditional NFTSM， the tracking errors are reduced twice time by NFTSM+ARBF+TTD method. Experimental results show the proposed method may be applied to shipborne rocket launcher AC servo systems. 

Predictive Controller of Cooperative Docking for Ship Platoon in Lock Waterway

LEI Chaofan, CHU Xiumin, LIU Chenguang, WU Wenxiang, LI Songlong,

2022, 33(04):  421-431.  DOI: 10.3969/j.issn.1004-132X.2022.04.006

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In order to improve the navigation efficiency and safety of the ships in the lock waterway， the control method of the coordinated stopping of the ship platoon in the lock waterway was studied herein. Based on the model predictive control principle， two methods of ship stopping control were proposed， namely， velocity-time method and velocity-displacement method. Aiming at the demands of the coordinated stopping control of ship platoon， the objective function of the coordinated stopping control of ship formation was designed in combination with the economy and smoothness of the stop. The coordinated stopping control of ship platoon was proposed based on the centralized model predictive control with the constraints of the longitudinal spacing and the input of the ship. The simulation results show that both the single-ship parking controller and the fleet parking controller have good control effectiveness. In contrast， the velocity-time method has obvious advantages in ride comfort， the velocity-displacement law performs better in economy， and has higher control accuracy and stability. 

State-of-the-art of Key Maritime Rescue and Salvage Equipment and Technology

ZHAO Jiechao, JIN Hao, CHEN Jian, PAN Changcheng, ZHANG Yingxiang, WANG Jiwu, WENG Datao

2022, 33(04):  432-451,458.  DOI: 10.3969/j.issn.1004-132X.2022.04.007

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 To promote the modernization of the national emergency management systems and capabilities， combined with the current development of maritime emergency rescue capabilities in China， the key issues exposed in some typical maritime emergency rescue cases in recent years were deeply analyzed， and the conclusion that “systematic construction” was the core issue that urgently needed to be strengthened in the construction of Chinese maritime rescue and salvage equipment and technology was pointed out. From the perspective of the land-sea-air-space integrated， aiming at the four major Chinese rescue and salvage missions of life rescue， environmental rescue， property rescue， and emergency rescue and salvage， this paper systematically divided the key equipment technology of maritime rescue and salvage into 7 types according to the dimensions of space-based， air-based， water surface， and underwater. Aiming at the current development of each type of key equipment technology， the Delphi method， brainstorming method and bibliometric method were used to carry out research and judgment on the development of key maritime rescue and salvage equipment and technology. The results of the study selected 13 key equipment technologies that require urgent attention from the 7 categories of key equipment technologies. Meanwhile， the current challenges faced by each key equipment technology were systematically analyzed， and recommendations for the development goals and core construction tasks in the next 5~15 years were given as well. 

Comparative Analysis of Thermodynamics Performances of ORC  Systems Recovering Waste Heat from Ship Diesel Engines

LUO Wenhua, CHEN Wu, JIANG Aiguo, TIAN Zhen

2022, 33(04):  452-458.  DOI: 10.3969/j.issn.1004-132X.2022.04.008

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ORC system was used to recover the waste heat of a certain type of ship diesel engines（maximum continuous rating 996 kW）. The performances of five different structure ORC systems were compared and analyzed on their net output powers. The results show that the maximum net output power of the basic ORC system that recovers the exhaust gas waste heat of the ship diesel engines is as 49.83 kW； by only adding a regenerator to further recover the waste heat of the expander outlet working fluid， the maximum net output power reaches 54.84 kW； while by adding a preheater to recover the waste heat of the ship diesel engine jacket cooling water， the number is up to 58.88 kW， which is 18.1% higher than that of the basic ORC systems. Using the independent dual-cycle ORC system to recover the waste heat of ship diesel engine exhaust gas and jacket cooling water simultaneously only make the maximum net output power 2.84% higher than that of the ORC system with preheater， which is as 60.6 kW. Therefore， considering of ship space constraints， operation and maintenance reliability， the ORC system with preheater should be given priority to recover the waste heat of the ship diesel engines.

Energy Consumption Modeling and Changing Laws of Main Types of Ships in Yangtze River Based on Time and Space Dimensions

2022, 33(04):  459-468.  DOI: 10.3969/j.issn.1004-132X.2022.04.009

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In order to study the energy consumption level and changing laws of the main types of ships on the Yangtze River， an energy consumption model for the main types of ships in the Yangtze River from the perspective of time and space was built based on the analysis of ship resistance and ship navigation environment. Through calculations， the energy consumption values of the main types of ships on the Yangtze River were obtained， and the law of energy consumption of different ship types with time and space was analyzed. The results show that the total energy consumption of dry bulk ships is the highest. When the ship sails against the river， the energy consumption is the largest in summer， and the energy consumption in the section from Fengjie to the dam is the lowest. When the ship sails down the river， the energy consumption is the largest in winter， and the energy consumption of the Wuhan-Shanghai segment is the lowest. Among ships with deadweight tonnage less than 2000 tons， container ships have the lowest energy consumption， and among ships with deadweight tonnage greater than 2000 tons， container ships have the highest energy consumption. 

Research Status of Key Technologies for Energy Management System of Marine Hybrid Propulsion Systems

SUN Xiaojun, SONG Enzhe, YAO Chong

2022, 33(04):  469-481,495.  DOI: 10.3969/j.issn.1004-132X.2022.04.010

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In the face of energy shortage and strict emission regulations， the use of new hybrid power system would become an important direction of ship development in the future. Firstly， the challenges were analyzed by the shipping industries， and the advantages and necessity of marine hybrid power were expounded. The topology and implementation framework of energy management systems were presented. Secondly， the research status of energy management strategy was analyzed, and the development route of hybrid system multi energy coupling energy management strategy was put forward. The challenges faced by the research and development of energy management strategies for marine hybrid power systems were explored ， and  the future development trends and in-depth research directions were looked forward. The paper provides the research and development directions for the green and intelligent development of marine hybrid powers. 

Research Progresses of Adaptive Spectral Shaping Active Control and Its Application in Naval Ship Fields

CHEN Tian, ZHANG Xingwu, LIU Jinxin, CHEN Xuefeng, YAN Ruqiang,

2022, 33(04):  482-495.  DOI: 10.3969/j.issn.1004-132X.2022.04.011

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The stealth performance of warship was an important performance and tactical index. Passive control technologies such as vibration absorption and isolation were widely used in the fields of vibration and noise reduction， but they still might not meet the needs of acoustic stealth of ships. Therefore， it was of great significance to study active vibration and noise control of the ships. The active spectral reshaping control might change the characteristics of radiated noises to acoustic stealth the ship. The connotation of spectrum reshaping active control was introduced, and three aspects of adaptive inverse control， adaptive active control and adaptive spectrum reshaping active control were summarized according to the development of adaptive spectrum reshaping active control theory. Finally， the effectiveness of the algorithm was verified by the applications in the field of naval ships. 

Research and Development for Preventive Maintenance-based Ship Grade Repair Decision-making Systems 

SONG Tingxin, HAN Guochen

2022, 33(04):  496-503.  DOI: 10.3969/j.issn.1004-132X.2022.04.012

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 The traditional periodic maintenance strategy often led to under-maintenance and over-maintenance of the ship equipment. To improve the scientificity of maintenance decision， a ship grade repair decision method was proposed based on the concept of preventive maintenance. According to the technical status and maintenance information of ship equipment， the failure mode and effectiveness analysis of key important components were carried out to determine their repair demand level and repair scope； meanwhile， the Weibull distribution model and the maximum likelihood estimation method were used to predict the median life of the equipment， and the production rules were defined； then， based on the three-level repair BOM structure of ship-system-critical parts， logic decision and rule reasoning were conducted from bottom to top to determine the repair grade and timing of the entire ship. A ship grade repair decision system was developed and functionally verified by cases， which might meet the application requirements of autonomous decision for ship grade repair and provide a feasible way for preventive maintenance of ships.