Spline structures are essential load-transmission components in mechanical systems, and their fretting wear behaviour directly affects system performance, service life and safety. In this work, 16MnCrS5 steel in the uncarburised and carburised states was used as the self-mated friction pair. A combination of fretting tests and microstructural characterisation was applied to analyse the fretting-damage interface, evaluate energy dissipation and material damage, and clarify the fretting wear behaviour and damage mechanisms of 16MnCrS5 steel before and after carburisation. Running condition fretting maps (RCFMs) and material response fretting maps (MRFMs) were established from Ft-D curves, fretting wear volume and wear morphology. The results show that, with increasing displacement or decreasing load, the Ft-D curves of both uncarburised and carburised 16MnCrS5 steel change from closed linear responses to semi-open loops and finally to open parallelograms. The partial slip region (PSR), mixed fretting region (MFR) and gross slip region (GSR) were clearly identified. From the PSR to the GSR, both wear volume and coefficient of friction increased markedly for 16MnCrS5 steel before and after carburisation. The RCFMs and MRFMs of the two material states were similar. Compared with the uncarburised samples, the carburised samples exhibited lower wear volume, lower energy dissipation and a higher system deformation rate. These differences in fretting wear behaviour were closely associated with phase composition, thermomechanical properties and wear-debris evolution in the two materials. Moreover, operating the spline within the PSR can substantially reduce wear.

With the increased power density of internal combustion engines (ICE) and growing demands for lightweight design, the connecting rod big-end bearings are subjected to significant alternating loads. Consequently, the interference–fit interfaces become susceptible to fretting damage, which can markedly shorten engine service life and impair reliability. In the present study, the effects of the big end manufacturing process, bolt preload, and bearing bush interference fit are considered to develop a coupled lubrication–dynamic model of the connecting rod big-end bearing. This model investigates the fretting damage issue in the bearing bush of a marine diesel engine’s connecting rod big end. The results indicate that the relatively low stiffness of the big end is the primary cause of bearing bush fretting damage. Interference fit markedly affects fretting wear on the bush back, whereas the influence of bolt preload is secondary; nevertheless, a decrease in either parameter enlarges the fretting distance. Based on these findings, an optimized design scheme is proposed.

Diesel engines with large power,long stroke and high explosive pressure are the main power equipment for the fields of transporta-tion,construction machinery,national defense equipment and nuclear emergency generators.During cole/hot start of the key kinematic pair piston ring-cylinder liner of a diesel engine,the upper and lower dead center positions of the cylinder liner are in a dry friction or lean oil lubrication state,which is prone to local abnormal wear and loss of power performance.In order to suppress the abnormal wear of piston ring-cylinder liner kinematic pair,MoS2 thin films were prepared on the surface of the piston ring by magnetron sputtering technology.The friction and wear performance of the friction pair of the piston ring,with MoS2 thin film added on its surface,and cylinder liner was evaluated using the SRV-Ⅳ micro motion friction and wear tester to simulate frequent cold/hot start conditions of diesel engines.Moreover,scanning electron microscopy(SEM)was used to characterize the microstructure of the MoS2 film and the surface morphology of the friction pair before and after friction.Results showed that compared with the original CKS piston ring and cylinder liner,the friction coefficient of MoS2 film piston ring-cylinder liner under dry friction condition was greatly reduced from 1.07 to 0.11,and the wear rate of cylinder liner was reduced from 8.61 × 10-6 mm3/(N·m)to 3.71 × 10-8mm3/(N·m).Under normal temperature and lean oil condition,the friction coefficient decreased from 0.18 to 0.11,and the wear rate decreased from 1.43×10-7 mm3/(N·m)to 3.22×10-8 mm3/(N·m).Under high temperature and lean oil condition,the friction coefficient declined from 0.12 to 0.08,and the wear rate was reduced from 7.08x10-8 mm3/(N·m)to 1.12×10-8 mm3/(N·m).Besides,the transfer of MoS2 films on the surface of the piston ring during the friction process was the main reason for the improvement of the tribological performance of the friction pair.

There are two methods for calculating fluid in porous materials, namely the pressure drop method (PDM) and the source term method (STM), which are widely utilized in their respective fields. Although in principle, the two methods can be applied interchangeably in each other's fields under certain conditions, this situation is extremely rare. This paper conducts a comparative study from various aspects to illustrate the advantages and disadvantages of each method. From a comparison of mathematical equations, PDM does not have the momentum equation, resulting in lower computational costs and better computational performance. From the simulation results of single porous media, STM has more sources of error, and the error in PDM mainly originates from the fitting method. Except for low Reynolds numbers, PDM is generally superior to STM. Both methods yield consistent results when the flow field is uniform. From the perspective of the coupling between porous media and pure fluid, STM captures flow details better. At low Reynolds numbers, STM's computation results are closer to experimental results. While at high Reynolds numbers, PDM aligns better with experimental results. Theoretically, PDM has higher computational efficiency, but it is difficult to achieve efficient coupling with the momentum equation. The computational efficiency of both methods is usually almost the same. In summary, both methods have their advantages and can be employed interchangeably under some conditions to achieve higher computational efficiency, accuracy, and convenience.

When leakage occurs in the titanium tubes of a nuclear power plant condenser, the ability to quickly and accurately locate the position of the leaking tubes holds significant importance for the safe and stable operation of the condenser. SF6 and He are commonly used tracer gases for pinpointing the location of leaking titanium tubes in large condensers. In order to investigate the diffusion behavior of these two different tracer gases in the condenser of a nuclear power unit, a three-dimensional computational fluid dynamics (CFD) model of the condenser was established based on the porous media. Concentration distribution characteristics and diffusion rate differences of SF6 and He inside the condenser are analyzed through transient analyses. The results indicate that the amount of tracer gas leakage significantly influences the time it takes for the tracer gas to diffuse to the suction port, and the location of tracer gas leakage has a significant impact on the concentration distribution pattern at the suction port. He exhibits a faster diffusion rate compared to SF6. When a leak occurs at location 1 of the B4 module with a leak rate of 0.007 kg/s, the mass concentration of He peaks at the suction port of the A3 module after ∼2.2 s, whereas the mass concentration of SF6 reaches its maximum at the suction port of the A3 module after around 9.5 s.

核电厂CRF循环水泵选用球面圆锥滚子轴承作为推力轴承,是重要的轴向承载部件,其外圈多次发生材料剥落损伤问题.对损伤的推力轴承开展化学成分、材料硬度、剥落微观形貌、显微组织、应力分布等分析,得出以下结论:推力轴承外滚道在过大载荷作用下会加速产生异常白色组织("蝴蝶斑"),从而发生材料疲劳剥落.该分析结果为核电厂CRF循环水泵的推力轴承选型和维修优化提供了理论支撑.

核电厂一回路主泵静压轴封现场运行期间,多次出现超出厂家运行技术要求的工况,由于缺乏主泵静压轴封运行参数影响机理研究,严重制约着轴封极限运行工况下的可靠性分析和评价.依托CPR1000核电机组100型核主泵双锥角静压轴封,提出一种流固耦合分析数值模型,系统阐述了极低压差、极限温度、内外锥角等关键因素对密封泄漏特性的影响机理.通过对极限工况运行可靠性进行研究,提出极限运行工况建议值,即压差不低于0.6 MPa,极限注入温度不高于100℃.可以为现场核主泵静压轴封极限工况下运行可靠性评价提供量化参考和指导.

核电厂核级泵定期试验出力性能偏差过大时,只能通过经验评价核级泵的可用性,存在运行风险.以某核电厂SEC泵为例,建立系统的一维仿真模型,根据系统设计参数和下游用户需求确定SEC系统的运行的极限边界,并采用性能曲线平移作图法,明确泵性能曲线的控制偏差.为系统相关的安全评估、设备管理、工程改造等工作提供重要依据.

This paper uses the finite element calculation software ABAQUS to research the stability characteristics of the drum-type screen drive under normal operating conditions. Through the simulation calculation of the dynamics of the reducer system, earthquake load and motor gravity, the results show that the drum-type screen drive secondary reduction worm gear drive components are subjected to the maximum stress, and the maximum stress occurs at the intersection of the worm and gear; the maximum deformation under the earthquake load occurs at the two low-speed motor sides, and the maximum displacement is 0.929mm.

某核电厂MTU956应急柴油发电机组在满功率试验中燃油精滤器大量漏油,并伴随燃气喷射.检查发现A5、A6、B9缸喷油器异常渗漏,导致柴油机紧急停机检修,造成大修关键路径延误.通过对喷油器建模进行密封性能校核以及对喷油器主要部件的材料学检测,结合对事发核电厂检修工艺的审视,诊断确认喷油器渗漏的根本原因为检修工艺转化不完善,对核电厂应急柴油机运维具有重要借鉴意义.

核主泵2号密封在事故工况下,需要承受一回路高压,由于缺乏2号密封在承受高压条件下的密封机理研究,严重制约2号密封承受高压时的可靠性分析和评价.依托CPR1000核电机组100型核主泵2号密封,提出一种流固耦合分析数值模型并通过台架试验验证,系统阐述了核主泵2号密封承受高压时由摩擦面密封向流体静压型密封的转变机理,并研究了动环锥角、泄漏量随压差增加的变化规律.通过数值研究,发现2号密封锥角和泄漏量在5 MPa压差左右出现拐点,动环锥角最大约为0.05°,随着压差进一步增加,动环锥角基本保持不变,泄漏量则随压差呈现近似线性上升.

通过数值计算与分析,发现引进型300MW汽轮发电机组的凝汽器存在上、下管束模块之间有左右贯通的水平蒸汽通道以及每个管束模块内无独立的空冷区两大技术缺陷,进而指出只有采用整体置换为先进管束才能显著改善凝汽器的热力性能.通过讨论管束水模拟试验和凝汽器全尺寸试验的局限性,指出数值模拟计算是研究现代大型电厂凝汽器热力性能的唯一有效方法.

核电厂堆芯指套管为核电厂反应堆中子通量测量探头提供导向和通道.指套管磨损泄漏将破坏核电厂反应堆一回路压力边界,严重影响核电厂安全稳定运行.分析核电厂反应堆指套管磨损过快的主要原因.针对磨损过快原因,分析和探讨各种指套管磨损治理技术的应用效果,为核电厂反应堆指套管磨损过快的问题解决提供参考借鉴.

某核电站多台重要厂用水泵轴封泄漏量频繁出现异常增大现象,泵解体后均发现最下方的一道盘根磨损严重,已经溃烂,其上方三道盘根磨损较轻,状态较好.本文采用有限元软件对盘根进行建模,拟合应力曲线,分析受力情况,发现苎纤水基材料盘根最下方的一道盘根整体所受到的摩擦力最大,而聚四氟乙烯材料盘根最上方的一道盘根所受摩擦力最大.

Recently, the technology of employing phase change materials (PCMs) for solar energy storage has grown more magnetic due to the focus of various latent heat storage investigations to solve the energy crisis. In this work, a novel and ecofriendly shape-stable phase change material based on a biological matrix was prepared through vacuum impregnation, which used porous carbon as a support substrate from Cyperus alternifolius (CA), polyethylene glycol (PEG) as the phase change medium, and silver nanoparticles attached to the matrix as the reinforcement factor. The superior porous structure of CA allows it to have a high loading rate of PEG. The multifunctionality of silver nanoparticles can increase the thermal conductivity of the bio-based shape-stable phase change material (BSPCM) up to 0.676 W/(m K), while also boosting its photo-thermal conversion efficiency to 82.7%. Furthermore, the Ag@BSPCM has an excellent melting enthalpy of 137.3 J/g, as well as outstanding thermal stability and reliability. Additionally, the great photo-to-thermal conversion efficiency of Ag@BSPCM (82.7%) and the significant anti-leakage capability bodes well for its future application. This demonstrates the prepared Ag@BSPCM proves its feasibility for thermal energy storage management and photo-thermal conversion.

某集团多个核电厂在小流量工况下启动冷却水泵(RRI泵),下游EAS系统换热器RRI侧安全阀会频繁出现起跳现象,导致RRI系统失效造成核安全风险.通过对比排查锁定安全阀起跳的根本原因,探结合国内外核电厂RRI系统设计差异、RRI887/888VN安全阀设计参数、EAS换热器RRI系统管道设计参数进行仿真分析计算,制定合理可行的纠正措施,最终攻克该技术难题,保障系统稳定运行.

This work aimed to investigate the effects of some Bi additions (x = 0, 1, 3, and 5 wt%) added to Sn–2Cu solder alloy on its thermal properties, mechanical performance, and resistance to corrosion, which was investigated by using the Differential scanning calorimetry, Scanning electron microscope, Vickers Hardness Tester, Universal testing machine, Electrochemical workstation, and X-ray diffraction. The experimental results showed that doping 5 wt% Bi could reduce the melting point from 239.7 to 226.6 °C and the undercooling from 24.0 to 9.0 °C, which could improve the thermal properties. Moreover, the Bi addition could refine the microstructure and decrease the Cu6Sn5 IMC phases’ size. With the addition of 5 wt% Bi, the microhardness and tensile strength reached the highest value of 20.13 HV and 57.64 MPa, respectively, due to the solid solution strengthening and precipitation strengthening. The electrochemical corrosion behaviors were performed to use the potentiodynamic polarization and electrochemical impedance spectroscopy. The obtained results revealed that a dense passivation film was formed on the surface of Sn–2Cu–1Bi alloy to prevent the alloy from being further corroded, which had the lowest value of corrosion current density (0.034 μA·cm−2) and biggest value of total resistance (200.4 kΩ·cm2). Therefore, the Sn–2Cu–1Bi alloy had best corrosion resistance.

Composite phase change materials have been extensively researched and applied in the field of thermal energy storage management and photo-thermal conversion. In this research, the loofah-based porous carbon (BPC) was modified with nano-Ag particles through chemical reduction method, and then a novel polyethylene glycol (PEG)/modified bio-based loofah porous carbon (BPC-Ag) shape-stable composite phase change material (SSPCM) was prepared. The experimental results indicated that the addition of nano-Ag particles not only considerably improved the thermal conductivity of the PEG/BPC-Ag composite PCMs (from 0.349 W m(-1) K-1 to 0.632 W m(-1) K-1) compared to the PEG/BPC composite PCMs, but also significantly improved its photo-thermal conversion efficiency (from 76.8 % to 92.3 %). In addition, the PEG/BPC-Ag has excellent thermal stability and reusability, which exhibited favorable phase change performance even after 100 thermal cycles. The results showed that the PEG/BPC-Ag has broad application prospects in the fields of photo-thermal conversion and thermal energy storage management.

针对某核电厂汽轮机进汽调节阀运行中突然关闭问题,文中对事件故障诊断分析采用了 X-RAY、超声波、CT断层扫描等无损检测方法,结合电路分析与实际测试方法,通过交叉对比试验,逐步锁定了电液比例阀设备故障的具体位置.先导阀LVDT中的远算放大器TL741I反向输入端存在分层缺陷,导致引脚存在接触不良,时钟信号输出波动,LVDT输出位置反馈异常.

通过使用AVL Excite PU软件和Abaqus软件的联合仿真,在大型V18柴油发电机上进行连杆大头轴瓦微动磨损分析,通过计算微动磨损指示参数(FIP)研究不同装配条件下轴瓦是否会产生微动磨损现象.结果表明:按照当前的装配条件,有可能会产生微动磨损,对于该大型发电机来讲小量级的轴瓦过盈量差别对于微动磨损的影响很小,并且如果螺栓预紧力施加小于设计所要求的力,产生微动磨损的可能性将增大.除此以外,本文对于连杆瓦座余高、连杆瓦座尺寸的上下偏差进行了不同的案例研究.