清管器聚氨酯皮碗接触性能分析与结构优选

为提高清管器的工作效率和工作性能,对清管器聚氨酯皮碗的类型及结构参数进行优选,通过分析清管器运行过程中碟形皮碗相较于直板皮碗的优势,优选碟形皮碗作为清管器的皮碗类型;对碟形皮碗进行力学分析并采用有限元软件Abaqus分析得出,过盈量和皮碗唇部厚度与接触长度呈正相关,皮碗唇部长度与接触长度呈负相关;接触应力随着过盈量和唇...     

1016mm清管器密封皮碗过盈量对其刚度特性的影响

直板型清管器是目前应用最为广泛、技术最成熟的清管器。密封皮碗作为直板清管器上的重要组件,起到建立清管器前后压差、推出管道杂物等作用。密封皮碗的过盈量直接影响密封皮碗的刚度特性。为了解1 016 mm管道清管器密封皮碗的刚度特性,以管径1 016 mm、壁厚21 mm的X70管道为研究对象,建立用于清管器密封皮碗二维轴对称有限元模型;计算分析密封皮碗在1 016 mm管径下过盈量改变的密封皮碗与管壁的接触压力、接触应力、弯曲应力、轴向弯曲距离、弯曲角度和弯曲直径的变化趋势;拟合出了以密封皮碗过盈量、厚度为参数的清管器密封皮碗等效刚度的曲线。     

变径清管器在变径长输管道的改进与应用

针对变径管道研发的清管器提高了管线的输送效率。清管作业中卡堵现象主要由皮碗过度磨损失去支撑性能造成,提出在清管器皮碗前后增加不同规格垫片的构想,利用垫片对皮碗形变的约束性,降低皮碗磨损产生不可逆形变的几率,且在前端起到支撑作用。在克独三管运行的结果表明:增加皮碗前后垫片在一定程度上降低了变径管道清管作业卡堵的风险。     

基于有限元分析方法的聚氨酯磨损规律研究

采用环块磨损试验机进行滴油润滑条件下聚氨酯材料的摩擦磨损试验,研究聚氨酯材料在不同压力、转速、磨损时间下的磨损情况。采用表面形貌测量仪测量磨损试样的磨痕深度,通过有限元分析软件Ansys计算不同试验压力下对磨面的接触压力,根据Rhee的磨损经验公式,通过对试验数据非线性回归拟合获得聚氨酯材料的磨损经验公式,拟合结果与实测结果吻合良好。     

基于真实压缩变形规律的柱状接触模型研究

摩擦学表面形貌研究在摩擦磨损中占有重要的比例,在轻载荷的时候尤为重要,通过对摩擦表面形貌的改造来改变材料的摩擦磨损性能,为寻找优化表面织构提供前期理论计算。在压力实验的基础上通过修正计算获得了材料的真实性能曲线,使用表面形貌测量仪测量摩擦磨损前后的试样和人造表面织构试样的表面形貌,在此基础上构造了真实接触表面,并由此构造了柱状接触模型,通过计算机编写表面接触模型计算软件,以实现不同形貌接触表面的摩擦学计算机仿真计算。仿真结果显示特定的人造表面织构可以提高承载能力进而提高表面的摩擦学性能,基于真实压缩变形规律基础上的柱状接触模型和数字化图像处理,可以很方便地对表面的静态承载能力做出量化评价。     

烷烃中少量芳烃的模拟移动床吸附及模拟

在实验研究烷烃中少量芳烃的模拟移动床吸附动态过程及其条件的基础上 ,用模拟移动床吸附模型进行了模型化拟合计算 ,传质采用线性推动力模型 ,得出轴向扩散系数和总传质系数。结果表明 :模拟移动床吸附动态模型的计算值与实验值相符 ;用吸附动态模型计算得出的轴向扩散系数与由关联式计算出的值相一致 ,且与流速成正比 ;总传质系数随着进料流量的增加而增大 ;区域 和区域 中 ,总传质系数随着温度和质量分数的升高而逐渐增大。区域 和区域 中 ,总传质系数随着温度的升高和质量分数的降低而逐渐减小。在低流量下 ,区域 和区域 中的总传质系数远比区域 和区域 中的总传质系数小。以上实验与计算结果为在直链烷基苯的生产过程中 ,降低循环烷烃中芳构化物的含量 ,实现延长脱氢催化剂的寿命提供了技术基础。     

管道清管器运行速度控制技术研究进展

随着对管道安全问题和降本增效理念的逐步重视,管道清管操作已成为全世界油气管道运行中必不可少的作业规程,清管器的运行速度是需要重点控制的参数之一,当其处于合理区间内时（原油管道1~5m/s,天然气管道2~7m/s）,清管效果最佳。本文基于对管道清管数学模型的研究,首先论述了不同的被动控制方法,认为该方法较为灵活,应用广泛,对不同入口条件下清管器速度的准确计算是能否控制清管器速度处于合理区间的关键;然后对不同的主动控制方法进行了研究,研究表明：射流清管器速度控制的核心是旁通率的优选,其依赖于压降系数、皮碗与管壁间摩擦力的准确计算,建立简便可靠的摩擦力工程计算模型将有助于射流清管技术应用的进一步推广;最终本文对清管器智能调速技术进行综述和展望,指出发展稳定可靠的国产智能调速技术是未来重点研究方向。     

陶瓷防护树脂基复合材料的磨损性能及机理研究

为了提高树脂基复合材料的耐磨损性能,采用Al2O3陶瓷贴片制备了陶瓷防护复合材料,通过往复式摩擦磨损试验机对陶瓷片材和复合材料进行了磨损性能试验,得到了防护复合材料在不同加载参数下的磨损形貌,进一步采用三维白光干涉表面形貌仪测试了磨损试样的表面形貌、磨痕深度与宽度,并据此建立了磨损性能数据分析与评价模型,分析了防护复合材料的耐磨损机理。结果表明:复合材料采用陶瓷贴片进行防护可大大提高其耐磨损性能,经陶瓷防护后,复合材料的可承受加载载荷从40 N提高至100 N;随着载荷的进一步增加,陶瓷防护复合材料的磨痕深度大大增加,而钢球的磨损程度迅速下降,其磨损机制发生了变化。分析了造成复合材料磨损性能发生变化的原因。     

压力容器活套法兰连接中金属O形密封环接触特性研究

金属O形密封环广泛应用于航天、核电等领域,其力学性能对密封结构有重要影响。为研究活套法兰结构中金属O形密封环接触特性影响规律,利用ABAQUS有限元软件建立了法兰模型,分析了O形密封环受力特征,以及内压、密封环安装位置及螺栓间距对O形密封环接触特性的影响规律。结果表明：介质压力增加,O形密封环最大接触应力先增加后减小,接触宽度减小;改变O形密封环安装位置后,密封环接触应力分布出现较大的波动,侧面与密封槽挤压产生接触应力;增大螺栓间距后,密封环上表面内侧接触区域和外侧接触区域最大接触应力差值减小,下表面内侧接触区域和外侧接触区域最大接触应力差值增大。本文结果可为法兰密封中密封环设计提供参考。     

基于FLUENT的金属丝网流阻仿真分析

金属丝网是压载水过滤器的关键部件,通过试验获得了三种型号金属丝网的流阻损失值,并绘制相应的流速-压差曲线图,拟合得出了滤网的性能参数,进行数值模拟仿真计算。通过试验结果与仿真模拟结果的对比分析,验证曲线拟合方法的正确性,证实了仿真模拟方法的可靠性,为滤网的设计与选型提供指导。     

Synthesis and characterization of CNTs/POM nanocomposite acetabular hip cup

Polyoxymethylene (POM) considered as the most appropriate alternative for ultra-high molecular weight polyethylene (UHMWPE) in the hip joint replacement application due to their biocompatibility, high mechanical properties, and cheapness. The wear is the main cause of the failure in the hip joint and the wear resistance of UHMWPE is still better than the wear resistance of POM. This research aims to improve the wear behavior of POM by blending it with 0.02?wt% of functionalized carbon nanotubes (CNTs) and using paraffin oil dispersion technique to obtain a uniform dispersion. The injection molding and machining process were used to produce the new (CNTs/POM) nanocomposite acetabular hip cup which has a high wear performance. The wear rate of the CNTs/POM cups was evaluated using a total leg joint’s simulator at 1,000?N for 3 million cycles under serum-based lubricated conditions. Moreover, the wear mechanism of cups was examined by scanning electron microscopy as well as the dispersion of CNTs inside the cup matrix. The results show that the wear resistance of POM cup has been improved by adding functionalized CNTs ～402% and ～221%, when compared with a virgin POM and UHMWPE, respectively, because of increasing the melting temperature and crystallinity degree.     

疏水表面液滴合并弹跳过程的数值模拟

液滴合并弹跳对强化热泵空调系统中的凝结传热及防结霜、除霜等方面均有良好的应用前景。在综合考虑固-液、气-固和气-液表面自由能,重力势能,液滴内部黏性耗散功及表面黏附功的基础上建立了液滴合并及弹跳的分阶段能量模型,并进行了超疏水表面不同半径液滴合并弹跳时的模型模拟与实验验证,得到较好的吻合。基于该模型研究了液滴数量、半径均匀性及不同表面状态对液滴合并弹跳过程的影响规律。结果表明,液滴数量增加时,合并阶段临界接触角由120°减小至105°,半径尺寸均匀性增加时,弹跳阶段临界接触角从140°减小至130°。当表面接触角大于140°时,固液接触系数影响微乎其微。可见,液滴数量的增多及液滴尺寸均匀性的提升有利于合并弹跳过程的发生,固液接触系数对合并弹跳过程的影响程度随表面接触角的增大而减小。     

Dry reciprocating sliding wear behaviour of alumina-silicon carbide nanocomposite fabricated by ceramic injection molding

The wear resistance of Al₂O₃ composite with 6 vol.% of SiC nanoparticles fabricated by thermoplastic forming technology and natural sintering was studied under reciprocating dry sliding conditions and compared with the results obtained in unreinforced alumina with similar grain size obtained by hot pressing. The nanocomposite wear resistance at contact loads of 20 N corresponding to initial Hertzian contact pressures of 1.8 GPa, was found to be superior to that of the alumina by a factor of 6.     

磨损对套管抗挤强度影响的有限元分析

通过建立磨损后套管三维模型导入ANSYS有限元软件的方法,分析了不同磨损程度对弯曲套管和直套管抗挤强度的影响。结果表明,随着磨损深度的增加,弯曲套管的剩余抗挤强度逐渐降低,且磨损深度与弯曲套管剩余抗挤强度基本呈线性关系;弯曲也会降低套管的抗挤强度。     

玻璃纤维填充改性PTFE复合材料的摩擦磨损性能

为改善聚四氟乙烯(PTFE)高磨耗的缺点,通过冷压烧结成型工艺制备了玻璃纤维(GF)填充改性PTFE复合材料,探究了不同GF添加比例的PTFE/GF复合材料在不同转速下的摩擦磨损情况。采用三维视频显微镜观察了样品的表面磨痕深度,并借助扫描电子显微镜观察摩擦表面形貌同时分析磨损机理。结果表明,填充GF后的PTFE复合材料其摩擦系数虽有一定程度的升高,但其体积磨损率却大幅降低。当GF质量分数为20%时,复合材料的体积磨损率降到最低,并在转速为80 r/min时较纯PTFE降低了93.56%。观察分析微观形貌发现,随着GF含量的增大,复合材料的磨损机理逐渐由纯PTFE的犁耕磨损和粘着磨损向磨粒磨损转变,当GF含量为25%时,出现轻微的疲劳磨损。     

掺粉煤灰混凝土的碳化及抗冻性能试验研究

研究了不同水胶比、不同粉煤灰掺量混凝土的碳化及抗冻性能。试验结果表明,随着水胶比和粉煤灰掺量的增加,混凝土碳化深度增加,混凝土碳化深度按方程D=K·tb回归,相关系数大于0.95;碳化深度与粉煤灰掺量及水胶比二元线性回归较好,混凝土抗压强度越高,抗碳化性能越好。水胶比是影响混凝土抗冻性能的主要因素,粉煤灰对混凝土抗冻性能具有不良影响。     

Densification during the formation of WC-based coating prepared by electric contact strengthening

In this study, the densification during the formation of WC-based coating prepared by electric contact strengthening (ECS) was investigated. Under increasing ECS process unit time, the surface and cross-sectional morphology, element distribution, hardness and phase composition of WC-based coating were detected. And the wear tests were conducted to test the coating performance. The results showed that, with the prolongation of ECS time, the coatings became denser while the porosity ratio decreased from 10.14% to 1.05%; The hardness of the coatings increased and the worn loss decreased continuously. It was found that, by the heating-pressing action of ECS, the WC-based powder geometry could maintain the original sphere shape, while the pores were filled gradually. The A4 coating showed the lowest wear rate. The densification mechanism was deduced that the intensified capillarity at the interface between the hard phase and binder phase due to the heating-pressing action, which showed forced infiltration and creeping behavior of the binding phase.     

Influence of Porosity on Friction and Wear of Tetragonal Zirconia Polycrystal

Sliding wear properties of ultra-fine-grained (180 nm) yttria-doped tetragonal zirconia (Y-TZP) ceramics were examined with porosities from 1.5% to 7%. On a pin-on-plate tribometer under dry-N₂ conditions, e.g., wear rates of the material increase by a factor of 5 by increasing porosity with a factor of 5 (from 1.5 to 7.0 vol%). In all cases no (irreversible) phase transformation to monoclinic zirconia took place during wear tests. The results for the relatively dense nanostructured materials showed significant evidence of plastic deformation and less microcrack formation. The morphology of the wear tracks in these ceramics indicate that the degree and amount of microcracks on the contact surface increased with porosity. A change in wear mechanism is observed.     

Direct Evaluation of the Bubble Point of Multicomponent Ideal Mixtures

Abstract

A direct method for the evaluation of the bubble point of multicomponent ideal mixtures is presented. The bubble point is less than the average boiling point by a temperature increment Δt. An equation was derived which gives the value of Δt in terms of the average boiling point t _aω and the total pressure π₍₁₎ calculated for a bubble point equal to t _aω For mixtures containing up to four components, a simple formula was found to give quite satisfactory answers. When the number of components increases up to 10, a correction factor was included leading to values of Δt with maximum error less than 2%.