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Design of Twin-Screw Compressor Rotor Tooth Profile with Meshing Clearance Based on Graphic Method and Alpha Shape Algorithm

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Journal of shanghai Jiaotong university(Science) 2023年第2期28卷 243-254页

作者：杨剑徐明照陆征 School of Mechanical engineering Shanghai Jiao Tong UniversityShanghai 200240China Shanghai Marine Diesel Engine Research Institute Shanghai 201108China

Rotor clearance is necessary for the safe operation of twin-screw compressors,and it has a major impact on the performance of twin-screw compressors.The purpose of this study was to obtain a rotor tooth profile with reasonable meshing clearance on the rotor end surface,so that the clearance on the rotor contact line would be uniform and the rotor could be smoothly meshed.Under ideal conditions,the rotor of a screw compressor should have no clearance or interference.However,owing to assembly errors,thermal compression,stress deformation,and other factors,a rotor without backlash modification will inevitably produce interference during operation.A new design method based on the Alpha shape solution was proposed to achieve an efficient and high-precision design of the clearance of the twin-screw rotor profile.This method avoids the complex analytical calculations in the traditional envelope principle.The best approximation of the points on the rotor conjugate motion sweeping surface in the points is illuminated using a specific color.The sweeping surface of the screw rotor single-tooth profile is roughly scanned to capture the base point set of the sweeping surface boundary points.The chord length and tilt angle of each interval are calculated using the value of the base point set to adjust the position,phase,and magnification of each interval sweeping surface.Finally,the data point set is converted to the same coordinate system to generate the conjugated rotor profile.An example was used to verify the feasibility and adaptability of this method.Based on the equidistant profile method,the clearance between male and female rotors of a screw compressor was obtained under actual operation conditions.Therefore,this study provides a basis for the meshing clearance design in the machining of twin-screw compressor rotors.

关键词： screw compressor thermal deformation Alpha shape algorithm equidistant profile method clearance

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Thermochemical Recuperation for Stirling engines by diesel Steam Reforming: Thermodynamic Analysis

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Journal of Thermal Science 2022年第6期31卷 2111-2123页

作者： LAN Jian GUO Qianzhen REN Zhe LYU Tian GU Genxiang HAN Dong Key Laboratory for Power Machinery and engineering Ministry of EducationShanghai Jiao Tong UniversityShanghai 200240China Shanghai Marine Diesel Engine Research Institute Shanghai 201108China

Thermochemical exhaust heat recovery is a prospective way to improve the thermal performance of Stirling engines. Based on Aspen HYSYS software, the simulation model of a Stirling engine combustor with a thermochemical recuperation(TCR) reformer was established to calculate the performance of the TCR system. The reforming temperature, fuel distribution ratio, steam-to-carbon ratio(S/C), and reforming pressure were changed to evaluate their effects on the reforming process and system efficiency. With increased reforming temperature, the equilibrium fuel conversion rate and heat recovery amount in the reformer gradually increase. The maximum combustor efficiency is achieved at the temperature of 600℃ and the fuel distribution ratio of 40%. With the S/C ratio increased from 1 to 2.5, the heat recovery rate and combustor efficiency increase significantly. The results show that the increase of fuel distribution ratio and S/C ratio leads to decreased reforming temperature, and external heat is needed to meet the heat balance for steam reforming. At a given reforming temperature and S/C ratio, increased reforming pressure results in decreased equilibrium fuel conversion rate and reforming reaction heat. At 5 MPa reforming pressure and 550℃ reforming temperature, the efficiency of the Stirling engine combustor is 92.7%, proving that the thermochemical recovery system can be applied to the Stirling engine under high pressure conditions.

关键词： Stirling engine thermochemical recuperation thermodynamic analysis fuel reforming heat recovery

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载人潜水器支持母船水下辐射噪声评估和试验分析研究

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哈尔滨工程大学学报（英文版） 2023年第2期22卷 334-343页

作者：邹祥依江国和叶林昌 Merchant marine College Shanghai Maritime UniversityShanghai 201306China Ship Department National Deepsea CenterShanghai 260000China Vibration and noise reduction Shanghai Marine Diesel Engine Research InstituteShanghai 200090China

This study investigates the underwater radiated noise(URN)of a manned submersible support mother ship.To this end,a detailed finite element model of the hull and outflow field is established,and the vibration wet mode of the scientific research ship is calculated.A combination of finite element and boundary element methods is used to analyze the spectral features of ship low-frequency URN.The URN source is comprehensively analyzed,the vibration energy is considered the basic parameter to describe the vibration,and the medium-and high-frequency URN of the ship are calculated using the statistical energy analysis.To obtain the full frequency-band URN of the ship,the risk position of exceeding the standard is determined,and the contribution of each main noise source in the ship to the URN is analyzed.The URN level of the ship is comprehensively measured in the free navigation state.The accuracy of the URN control evaluation model,and the method of the ship are verified.The data support for the ship to apply for the classification society certificate provides a scheme reference for the URN control of other scientific research ship in the future.

关键词： Scientific research ship Manned submersible Mother ship Underwater radiated noise Noise source Experimental measurement

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A flexible and smart shape memory alloy composite sheet based on efficient and bidirectional thermal management

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International Journal of Smart and Nano Materials 2022年第2期13卷 315-329页

作者： Yang Yang Yongquan Wang Tao Yao Xiaojuan Feng School of Mechanical engineering Xi’an Jiaotong UniversityXi’an People’s Republic of China Shanghai Marine Diesel Engine Research Institute Shanghai People’s Republic of China

Leveraging advances in shape memory alloys(SMAs)and flexible thermoelectric devices(f-TEDs),this paper presents a structural and functional integrity composite sheet to address the inefficient and bulky activation of 2-D SMAs.A series of experimental tests were performed to reveal the generation,change,and transfer mechan-isms of different types of electrically-induced heat in the f-TED,as well as the temperature-induced SMA phase transformation beha-viors.The results show that the composite sheet exhibited good bidirectional thermal management capacity.The austenite defor-mation can be completed within 10s at an operating current of 2 A.The cooling recovery,in particular,performs much better than in conventional modes(the temperature declines exponentially with time).Finally,through two functional prototypes,a light switch and a flexible gripper,the application potential of the proposed com-posite was further experimentally demonstrated.

关键词： Shape memory alloy flexible thermoelectric device bidirectional thermal management actuator thermomechanical

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基于有限元的新型科学考察船振动响应分析

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Journal of marine Science and Application 2022年第2期21卷 69-81页

作者：邹祥依江国和叶林昌 Merchant marine College Shanghai Maritime University201306China Ship Department National Deepsea Center260000China Vibration and noise reduction Shanghai Marine Diesel Engine Research Institute200090China

To control the vibration level of ships under construction,MSC Software’s Patran&Nastran modeling solutions can be used to establish a detailed finite element model of a new manned submersible support mother ship based on a line drawing,including the deck layout,bulkhead section,and stiffener distribution.After a comprehensive analysis of the ship simulation conditions,boundaries,and excitation forces of the main operating equipment,modal analysis and calculation of the ship vibration can be conducted.In this study,we calculated and analyzed the vibration response of key points in the stern area of the ship’s main deck and the submersible warehouse area under design loading working conditions.We then analyzed the vibration response of typical decks(including the compass deck,steering deck,captain’s deck,forecastle deck,and main deck)under the main excitation forces and moments(such as the full swing pod and generator sets).The analysis results showed that under DESIDEP working conditions,the vibration of each deck and key areas of the support mother ship could meet the vibration code requirements of the ship’s preliminary design(using the pod excitation and generator sets).Similarly,the vibration response of a scientific research ship under other loading conditions also met the requirements of the code and provided data support for a comprehensive understanding of the ship’s vibration and noise levels.Using actual vibration measurements,the accuracy of the vibration level simulations using finite element modeling was verified,the vibration of each area of the ship comfortably meeting the requirements of the China Classification Society.

关键词： Scientific research ship Vibration Modal analysis Risk assessment Finite element modeling

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Experimental Study and Simulation of Cavitation Shedding in diesel engine Nozzle using Proper Orthogonal Decomposition and Large Eddy Simulation

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Journal of Thermal Science 2023年第4期32卷 1487-1500页

作者： HE Jiajun AN Qingsong JIN Jiangshan FENG Shuai ZHANG Kemu Key Laboratory of Medium-Low Temperature Thermal Energy Efficient Utilization of Ministry of Education School of Mechanical EngineeringTianjin UniversityTianjin300350China Shanghai Marine Diesel Engine Research Institute Shanghai201108China

The unsteady cloud cavitation shedding in fuel nozzles greatly influences the flow characteristics and spray break-up of fuel,thereby causing erosion damage.With the application of high-pressure common rail systems in diesel engines,this phenomenon frequently occurs in the nozzle;however,cloud cavitation shedding frequency and its mechanism have yet to be studied in detail.In this study,a visualization experiment and proper orthogonal decomposition(POD)method were used to study the variations in the cavitation shedding frequency and analyze the cavitation flow structure in a 3 mm square nozzle.In addition,large eddy simulation(LES)was performed to explore the causes of cavitation shedding,and the relationship between cavitation and vortices.With the increase of the inlet and outlet pressure differences,and fuel temperatures,the degree of cavitation intensified and the frequency of cavitation cloud shedding gradually decreased.LES demonstrated the relationship between the vortices,and the development,shedding,and collapse of the cavitation clouds.Further,the re-entrant jet mechanism was found to be the main reason for the shedding of cavitation clouds.Through comparative experiments,the fluctuation of the vapor volume fraction in the nozzle hole accurately predicted the regions with stable cavitation,re-entrant jet,cavitation cloud shedding,and collapse.The frequency of cavitation shedding can then be calculated.This study employed an instantaneous POD method based on instantaneous cavitation images,which can distinguish the evolution process and characteristics of cavitation in the nozzle hole of diesel engines.

关键词： diesel engine proper orthogonal decomposition cavitation shedding cavitation collapse large eddy simulation

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Pre-chamber turbulent jet ignition of methane/air mixtures with multiple orifices in a large bore constant volume chamber: effect of air-fuel equivalence ratio and pre-mixed pressure

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Frontiers in Energy 2019年第3期13卷 483-493页

作者： Xiang LI Wenzheng ZHANG Zhong HUANG Dehao JU Li HUANG Mingzhi FENG Xingcai LU Zhen HUANG Key Laboratory of Power Machinery and engineering Ministry of EducationShanghai Jiao Tong UniversityShanghai 200240China Shanghai Marine Diesel Engine Research Institute Shanghai 201108China

Liquefied natural gas (LNG), mainly composed of methane, is in progress to substitute diesel fuel in heavyduty marine engine for practical, economic, and environmental considerations. However, natural gas is relatively difficult to be ignited in a large bore combustion chamber. A combustion enhancement technique called prechamber turbulent jet ignition (TJI) can permit combustion and flame propagation in a largebore volume. To investigate the effect of air-fuel equivalence ratio and pre-mixed pressure on pre-chamber TJI of methane/air mixtures with multiple orifices in a large bore volume, experimental tests and computational simulations were implemented to study the discharge of hot turbulent jets from six orifices of the pre-chamber. Different initial pressures and air-fuel equivalence ratios were considered to analyze the characteristics of TJI. The asymmetry of the turbulent jet actuated from six different orifices were found due to the asymmetric orientation of the spark plug, resulting in the inhomogeneous distribution of combustion in the constant volume chamber, which should be considered seriously in the marine engine design. Besides,as the premixed pressure increases, it has more effect on the flame propagation and plays a more important role, as it further increases.

关键词： marine engine natural gas methane turbulent jet ignition (TJI) pre-chamber

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Hydrodynamic characteristics and noise reduction mechanism of a wave leading hydrofoil placed in the wake of a cylinder

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Journal of Hydrodynamics 2023年第6期35卷 1089-1100页

作者： Bing Zhu Yue Li Wen-jun Xu Wei Zhang School of Energy and Power engineering University of Shanghai for Science and TechnologyShanghai200093China National Key Laboratory of marine engine Science and Technology Shanghai201108China marine Design and research institute of China Shanghai200011China

We have investigated the hydrodynamic and acoustic performance of a hydrofoil with a wave leading edge that is being ingested in a cylindrical wake,to explore the interaction and noise reduction mechanism with the use of near flow field and far field noise decoupled prediction methods of large eddy simulation(LES)and Ffowcs Williams-Hawkings(FW-H).Our results indicate that the wave leading edge has minimal effect on the hydrodynamic performance,however,it has demonstrated the ability to significantly improve the acoustic performance.Through the comparison of sound pressure level(SPL)and acoustic directivity,we have observed that the wave leading edge can significantly reduce the broadband noise in the far field.This is due to its ability to break the large-scale structure of the incoming flow,which weakens the direct impact and therefore reduces the tone noise.Additionally,the interaction between the broken vortex and the boundary layer around the hydrofoil surface is weakened,leading to a reduction in surface pressure pulsation and broadband noise intensity.The wave structure primarily affects the flow structure near the leading edge,resulting in a reduction in flow disturbance and sound source intensity,and an improvement in the acoustic feedback loop between the foil and the fore-cylinder.

关键词： Wave leading hydrofoil cylinder wake ingesting turbulence noise reduction large eddy simulation(LES)

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Facile preparation of core-shell Si@Li4Ti5O12 nanocomposite as large-capacity lithium-ion battery anode

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Journal of Energy Chemistry 2020年第1期29卷 89-98,I0004页

作者： Mengjing Liu Hanyang Gao Guoxin Hu Kunxu Zhu Hao Huang School of Mechanical and Power engineering Shanghai Jiao Tong UniversityShanghai 200240China School of Mechanical engineering Hangzhou Dianzi UniversityHangzhou 310018ZhejiangChina Shanghai Marine Diesel Engine Research Institute Shanghai 200090China

As a promising alternative anode material,silicon(Si)presents a larger capacity than the commercial anode to achieve large capacity lithium-ion batteries.However,the application of pure Si as anode is hampered by limitations such as volume expansion,low conductivity and unstable solid electrolyte interphase.To break through these limitations,the core-shell Si@Li4Ti5O12nanocomposite,which was prepared via in-situ self-assembly reaction and decompressive boiling fast concentration method,was proposed in this work.This anode combines the advantages of nano-sized Si particle and pure Li4Ti5O12(LTO)coating layer,improving the performance of the lithium-ion batteries.The Si@Li4Ti5O12 anode displays a high initial discharge/charge specific capacity of 1756/1383 m Ahg^-1 at 500 mAg^-1(representing high initial coulombic efficiency of 78.8%),a large rate capability(specific capacity of 620 mAhg^-1 at4000 mAg^-1),an outstanding cycling stability(reversible specific capacity of 883 mAhg^-1 after 150 cycles)and a low volume expansion rate(only 3.3% after 150 cycles).Moreover,the synthesis process shows the merits of efficiency,simplicity,and economy,providing a reliable method to fabricate large capacity Si@Li4Ti5O12nanocomposite anode materials for practical lithium-ion batteries.

关键词： Si@Li4Ti5O12 composites Core-shell nanoparticles In-situ self-assembly Decompressive boiling concentration Lithium-ion battery anode

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A New Accelerator for Convolution Neural Network

A New Accelerator for Convolution Neural Network

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第40届中国控制会议

作者： Fan Wu Jie Song Haoran Zhuang China Shipbuilding Industry Corporation Shanghai Marine Diesel Engine Research Institute

Deep learning and neural network technologies have surpassed traditional algorithms in many applications and have been increasingly used.Neural network algorithms require a lot of computing operations and have high requirements for hardware.Hardware accelerators are getting more and more attention.To design a high-performance convolutional neural network accelerator,this paper proposes a new accelerator circuit design method.The accelerator is programmable and supports layer-by-layer optimization for the CNN network,which realizes the better acceleration scheme for the computing and storage requirements of a specific network.The accelerator provides the ability to quantize different types of data to half-precision,which can reduce memory access.The accelerator can reach a peak performance of 211GOP/s under a 40nm SMIC CMOS process at 200 MHz operating frequency.A VGG16 network is implemented on our accelerator,and the delay of the convolution operation is 442.7 milliseconds.

关键词： Programmable convolutional neural network accelerator deep learning FPGA

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