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Experimental Study on Diesel Spray and Flame Asymmetry Characteristics of Dual-Orifice Nozzles for a Medium-Speed Engine

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Journal of Thermal Science 2025年第1期34卷 303-322页

作者： JU Dehao LIURui ZHENG Liang DENG Jiahui ZHANG Wenzheng HUO Jinlu HUANG Li Shanghai Marine Diesel Engine Research Institute Shanghai 201108China National Key Laboratory of Marine Engine Science and Technology Shanghai 201108China Key Laboratory for Power Machinery and Engineering Ministry of EducationShanghai Jiao Tong UniversityShanghai 200240China

The asymmetry of the multi-orifice spray will cause uneven heat load of the marine diesel engine,thereby affecting its working performance and service ***,an in-depth understanding of the spray and flame characteristics of multi-orifice nozzles will guide the optimization of the nozzle structure,needle design and diesel atomization and combustion *** this reason,four groups of dual-orifice nozzles with different hole diameters(0.1-0.55 mm)and mass flow rates covering the typical marine medium-speed diesel injections are designed and customized,and the constant volume chamber(CVC)with high temperature and pressure is used to simulate the actual in-cylinder working conditions of the diesel engine for the spray visualization *** study the asymmetry of the fuel sprays discharged from a diesel injector,the multi-orifice nozzle is simplified as a dual-orifice nozzle in this *** with X-ray Computed Tomography(CT)imaging technology,the influences of the nozzle internal structure on the spray and flame asymmetry are studied in the constructed supercritical *** is found that the asymmetry of the inlet angle and the equivalent length-diameter ratio is positively correlated with the inconsistency of the dual *** an increase in the injection pressure and nozzle diameter,the asymmetry of the dual spray becomes more pronounced,resulting in greater disparities in the ignition delay times and ignition positions of the two ***,the increase in nozzle diameter also leads to combustion instability,resulting in a flame with a serrated *** the increase of ambient temperature,the proportion of liquid phase in the jet decreases and the relative density of spray front decreases.

关键词： dual-orifice nozzle nozzle structure atomization spray flame asymmetry

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Interaction between the Microwave Plasma Generation and the Saturated Voltage during Microwave Pulse Assisted Ignition in ICE Lean Combustion

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Journal of Thermal Science 2025年第2期34卷 639-652页

作者： SUN Wei CUI Yi SONG Dawei TONG Zongpeng WU Huimin WANG Zhaowen The Key Laboratory for Power Machinery and Engineering of the Ministry of Education Shanghai Jiao Tong UniversityShanghai200240China Shanghai Marine Diesel Engine Research Institute Shanghai200090China School of Energy and Power Engineering Huazhong University of Science and TechnologyWuhan430074China

Microwave-assisted ignition(MAI)is a promising technology to improve the ignition stability in internal combustion engines under lean *** investigate the interplay between the microwave pulses and the electrical characteristics of ignition plasma,the high-time-resolved electrical characteristics of MAI are measured based on the discharge voltage and current profiles with microwave power varying from 0 to 1000 *** effects of microwave pulse on the electrical characteristics in the breakdown and glow discharge phases are discussed *** results show that the microwave-induced-voltage-decline(MIVD)occurs during the glow discharge phase,which originates from the increment of free electrons and the additional microwave ***,this voltage decline is insignificant in the breakdown ***,as the free electron number reaches a critical value,a shining plasma can be observed between the gap of electrodes and the voltage decline is stabilized to a"saturated voltage curve".Ultimately,the effect of microwave plasma on the enhancement of ignition kernel area is *** result indicates that the enhancement effect increases with plasma duration *** enhancements of earlier-generated plasmas are more significant than those of subsequent plasmas due to the distance limit of the plasma propulsive effect.

关键词： microwave assisted ignition electrical diagnosis saturated voltage curve microwave plasma ignition enhancement

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Observation and Assessment of Heat Transfer Coefficient of Thermal Discharge for Coastal Nuclear power Plants

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Journal of Ocean University of China 2025年第2期24卷 281-288页

作者： ZHU Qichao HUANG Chuanjiang XIA Yuzhuo YANG Ying GUO Jingsong XIA Changshui QIAO Fangli State Key Laboratory of Nuclear Power Safety Technology and Equipment Shenzhen 518172China China Nuclear Power Engineering Co. Ltd.Shenzhen 518172China First Institute of Oceanography Ministry of Natural ResourcesQingdao 266061China Key Laboratory of Marine Science and Numerical Modeling Ministry of Natural ResourcesQingdao 266061China

The heat transfer coefficient of the water surface is an important parameter in the design of thermal discharge in nuclear power plant *** this study,in situ observations were performed in the northwestern South China Sea near a coastal nuclear power plant to evaluate the applicability of heat transfer coefficient calculation algorithms commonly used in marine thermal discharge engineering in *** results show that the Regulation for Hydraulic and Thermal Model in Cooling Water Projects(SL 160-2012)is not applicable in calculating the heat transfer coefficient in offshore *** 160-2012 significantly overestimates the heat loss at the sea ***,Code for Design of Cooling for Industrial Recirculating Water(GB/T 50102-2014)performs well,and its estimation coefficient is roughly consistent with the estimations of the COARE 3.6 bulk algorithm,which is extensively used in physical oceanography for calculating air-sea heat fluxes,and the Gunneberg *** a 3-day observation,the average heat transfer coefficients estimated using these three algorithms were 50.4,48.5,and 48.8 W m^(-2)℃^(-1),respectively,with a deviation of less than 4% among them,whereas that estimated using SL 160-2012 was as high as 176.3 W m^(-2)℃^(-1).The abnormally large value of SL 160-2012 is due to its additional cooling term,which is artificially increased by 100 times because of the incorrect unit conversion used when developing the *** this error is corrected,the value will decrease to 50.5 W m^(-2)℃^(-1),which is very close to the estimation of GB/T 50102-2014.

关键词： heat transfer coefficient thermal discharge sea-air heat flux temperature rise nuclear power plant COARE algorithm

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ZIF-8 Modified Ce-Sol-gel Film on Rebar for Enhancing Corrosion Resistance

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Acta Metallurgica Sinica(English Letters) 2024年第12期37卷 2121-2135页

作者： Yanwei Zeng Peng Xu Guoqiang Liu Tianguan Wang Bing Lei Zhiyuan Feng Ping Zhang Guozhe Meng Marine Corrosion and Protection Team School of Chemical Engineering and TechnologySun Yat-sen UniversityZhuhai519082China Key Laboratory of Harbor and Marine Structure Durability Technology Ministry of TransportCCCC Fourth Harbor Engineering Institute Co.LtdGuangzhouGuangzhou510220China Department of Civil and Environmental Engineering Faculty of Science and TechnologyUniversity of MacaoTaipaMacao SARChina

Chloride-induced corrosion of steel reinforcement is the key factor leading to the degradation of reinforced concrete building *** the corrosion resistance of oxide scale of rebar has always been a research hotspot in the field of civil engineering materials.A ZIF-8 modified Ce-Sol-gel(ZCS)film was prepared on oxide scale of plain steel rebars by sol-gel *** is observed that the|Z|_(0.01 Hz)value of the ZCS film reached 320 kΩcm^(2),which is about 29 times higher than that of blank rebar in simulated concrete pore(SCP)solution with 0.1 M ***,they were inserted into mortar block and curing them in a curing box at T=20±2℃and RH=95±2%for 28 ***,these samples were subject to electrochemical impedance spectroscopy in 3.5 wt%***|Z|_(0.01 Hz)value of the rebar with the ZCS film was six times higher than that of the blank rebar after immersing for 20 days,resulting in an overall increase in corrosion resistance for *** results indicated that the modification by ZIF-8 could reduce the porosity of Ce-sol-gel(CS)film and improved the“labyrinth effect”of the ***,the negative charge on the surface of ZIF-8 in alkaline condition increased the repulsion effect with Cl−,significantly reducing the sensitivity of rebar to Cl−.

关键词： Chloride corrosion Oxide scale Rebar Sol-gel Corrosion resistance

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Analysis of a simplification strategy in a nonhydrostatic model for surface and internal wave problems

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Acta Oceanologica Sinica 2023年第2期42卷 29-43页

作者： Jinghua Zhang Wensheng Jiang Xueqing Zhang Key Laboratory of Marine Environment and Ecology of Ministry of Education Ocean University of ChinaQingdao266100China Tianjin Research Institute for Water Transport Engineering Ministry of TransportTianjin300456China Physical Oceanography Laboratory/Qingdao Collaborative Innovation Center of Marine Science and Technology Ocean University of ChinaQingdao266100China Pilot National Laboratory for Marine Science and Technology(Qingdao) Qingdao266237China

This paper examines the simplification strategy of retaining only the nonhydrostatic effect of local acceleration in a three-dimensional fully nonhydrostatic model regarding the submesoscale wave phenomenon in the *** scale analysis of the vertical component of the Reynold-averaged Navier-Stokes(RANS)equation was performed,confirming the rationalization of this ***,the simplification was implemented in a RANS equation-based nonhydrostatic model NHWAVE(nonhydrostatic WAVE)to make a simplified nonhydrostatic *** examples were taken to test its performance,including surface sinusoidal waves propagating on an idealized East China Sea topography,tidally induced internal lee waves and small-scale solitary *** results show that in a considerably wide range of nonlinear strengths,the simplified nonhydrostatic model can obtain similar results as those in the fully nonhydrostatic model,even for smaller-scale solitary *** influences the applicability of the *** stronger the nonlinearity is,the worse the simplified model describes the nonhydrostatic *** general,the simplified nonhydrostatic model can simulate surface waves better than internal *** of computational efficiency in the simplified nonhydrostatic model is reasonable,reducing the central processing unit time duration in the fully nonhydrostatic model by 16.4%–20.6%.The specially designed algorithm based on the simplified nonhydrostatic equation can remarkably reduce the computational time.

关键词： simplification of nonhydrostatic model submesoscale wave internal lee wave

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Simulation and verification of cylinder head's temperature field for marine low-speed engine 3

Simulation and verification of cylinder head's temperature f...

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2023 3rd International Conference on Computational Modeling, Simulation and Data Analysis, CMSDA 2023

作者： Hu, Lei Chen, Yangfan Luo, Qiang School of Naval Architecture Ocean and Energy Power Engineering Wuhan University of Technology Wuhan430063 China Key Laboratory of Marine Power Engineering and Technology of Ministry of Transport Wuhan430063 China School of Information Engineering Wuhan University of Technology Wuhan430070 China

The high load capacity of marine low-speed engines poses a challenge to the thermal load of the cylinder head and temperature field simulation can guide its structural design and optimization. The 3-dimensional models of the fluid domain for the cooling water and the solid domain for the cylinder head are established and meshed, the fluid domain model is simulated to research the heat transfer pattern by Fluent software, and the surface temperature and heat transfer coefficient of the cooling water is calculated. The thermal boundary conditions of the gas in the cylinder are simulated through the analysis of the engine working process. The temperature of the cylinder head is calculated based on the fluid-structure interaction model with the thermal boundary conditions by Workbench software. The validation of the model is carried out by comparing the simulated and measured temperature data in the heated inner wall of the cylinder head. The research results show that compared with the measured value, the error of simulation results is small, which shows that the model and method are reasonable. The temperature in the inner wall of the combustion chamber is low, which can provide possibilities to appropriately improve the power density of the low-speed engine and reduce the risk of low-Temperature corrosion. © Published under licence by IOP Publishing Ltd.

关键词： Cooling water

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Friction reduction behavior of oil-infused natural wood

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Friction 2022年第11期10卷 1824-1837页

作者： Shutian LIU Conglin DONG Chengqing YUAN Xiuqin BAI School of Transportation and Logistics Engineering Wuhan University of TechnologyWuhan 430063China Key Laboratory of Marine Power Engineering&Technology(Ministry of Transport) Wuhan University of TechnologyWuhan 430063China Polymer Technology Department of Mechanical EngineeringEindhoven University of TechnologyEindhoven 5600 MBthe Netherlands

Natural materials tend to exhibit excellent performance in the engineering field because of their structure and special functions.A natural red willow,called natural porous wood material(NPWM),was found,and wear tests were conducted to determine its potential as an oil-impregnated material by utilizing its special porous *** treatment was adopted to improve the NPWM properties for absorbing and storing lubricating *** different contributions of soaking and fluorination-soaking treatments on the tribological properties of NPWMs and their respective mechanism of effect were *** results showed that the fluorination-soaking treatment helped absorb and store sufficient lubricating oil in the NPWM porous structure;therefore,more lubricating oil would be squeezed out and function as a tribol-film between contacting surfaces during the friction process,thus ultimately contributing to stable and smooth wear responses even under prolong ***,the formation of an oil-in-water emulsion,caused by the buoyancy effect,destroyed the oil films on the worn NPWM surface in a water environment,resulting in higher coefficients of friction(COFs)under water conditions than under dry friction,even after the fluorination-soaking *** knowledge gained herein could not only verify the potential of NPWM as an excellent oil-impregnated material in the engineering field but also provide a new methodology for the design of artificial porous materials with stable and smooth friction processes.

关键词： natural porous material oil infusion treatment fluorination frictional behaviors

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Multi-Robot Task Allocation Using Multimodal Multi-Objective Evolutionary Algorithm Based on Deep Reinforcement Learning

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Journal of Shanghai Jiaotong university(Science) 2024年第3期29卷 377-387页

作者：苗镇华黄文焘张依恋范勤勤 Logistics Research Center Shanghai Maritime UniversityShanghai 201306China Key Laboratory of Control of Power Transmission and Conversion of Ministry of Education Shanghai Jiao Tong UniversityShanghai 200240China Key Laboratory of Marine Technology and Control Engineering of Ministry of Communications Shanghai Maritime UniversityShanghai 201306China

The overall performance of multi-robot collaborative systems is significantly affected by the multi-robot task *** improve the effectiveness,robustness,and safety of multi-robot collaborative systems,a multimodal multi-objective evolutionary algorithm based on deep reinforcement learning is proposed in this *** improved multimodal multi-objective evolutionary algorithm is used to solve multi-robot task allo-cation ***,a deep reinforcement learning strategy is used in the last generation to provide a high-quality path for each assigned robot via an end-to-end *** with three popular multimodal multi-objective evolutionary algorithms on three different scenarios of multi-robot task allocation problems are carried out to verify the performance of the proposed *** experimental test results show that the proposed algorithm can generate sufficient equivalent schemes to improve the availability and robustness of multi-robot collaborative systems in uncertain environments,and also produce the best scheme to improve the overall task execution efficiency of multi-robot collaborative systems.

关键词： multi-robot task allocation multi-robot cooperation path planning multimodal multi-objective evo-lutionary algorithm deep reinforcement learning

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Progress in Research on marine Litter-Related Monitoring Technologies 5

Progress in Research on Marine Litter-Related Monitoring Tec...

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2023 5th International Conference on Advanced Materials and Ecological Environment, AMEE 2023

作者： Liu, Haiying Wang, Mingqi Tang, Haitian Zhang, Hanlin Tianjin Research Institute for Water Transport Engineering Key Laboratory of Environmental Protection Technology on Water Transport Ministry of Transport China Yantai Marine Environment Monitoring Central Station of State Oceanic Administration China

The problem of marine litter pollution is becoming increasingly serious and has become one of the important global environmental issues. From the perspective of source and sink, floating riverine litter (FRL) is the main source of floating marine litter (FML), while beach litter (BL) and FML are the source and sink of each other. It is necessary to research the transformation mechanism and collaborative governance policy among these three kinds of marine litter, based on accurate monitoring data. However, conventional monitoring methods have problems such as high labor costs, insufficient representativeness and poor comparability. Hence, developing efficient and intelligent monitoring technology is the focus of recent future. Since 2018, monitoring technique of marine litter relevant research literature has grown rapidly, showing this technique a hot spot. In this paper, the relevant research literature is divided into three litter types (BL, FML, and FRL) and two ways (fixed monitoring and mobile monitoring). Similarities and differences in research focus, platform selection, result accuracy and result application are summarized and reasoned, with a view to accelerating the research progress and better supporting BL, FML, and FRL control in China. © Published under licence by IOP Publishing Ltd.

关键词： Metadata

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Numerical study on roll dynamics of damaged ship in beam waves and calm water

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Journal of Hydrodynamics 2023年第3期35卷 482-497页

作者： Zhi-yun Huang Zhi-liang Gao Sang-ming Xu Key Laboratory of High Performance Ship Technology Ministry of Education Wuhan University of TechnologyWuhan 430063China Wuhan University of Technology College of Marine and Energy Power EngineeringWuhan 430063China Union Strong(Beijing)Technology Co. LtdBeijing 100176China

Computational fluid dynamics is used to study the roll dynamics of a damaged ship in beam waves with various steepnesses and in calm *** wave-making method,which combines the velocity-inlet boundary and momentum source with the fifth-order Stokes theory,is employed for wave *** SST k-ωturbulence model with a modification to the turbulent viscosity in Reynolds stress is adopted to prevent the over-production of turbulence in the numerical wave *** lateral drift restrained model with a combined dynamic mesh strategy is utilized to deal with the coupled heave-sway-roll motions of the ***,benchmarking tests are performed,including wave generation and roll response of the damaged ship in regular beam ***,the effects of incident wave steepness on the roll response of the damaged ship are *** different wave steepnesses,the ship roll motion is dominated by the first-order harmonic *** second-order component increases with the increase of wave ***,the roll hydrodynamic coefficients for different parts of the damaged ship are investigated with different rolling *** added moment of inertia for the whole damaged ship is mainly attributed to the external hull composition and changes slightly with the change of roll amplitude and *** added moment of inertia for the compartments could be negative in particular *** damping coefficients of the whole damaged ship and external hull increase with the increase of roll amplitude and frequency,while that of the compartments appears complicated with the change of roll amplitude and frequency.

关键词： Damaged ship roll dynamics wave steepness hydrodynamic coefficients computational fluid dynamics(CFD)

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