Sealing properties and structure optimization of packer rubber under high pressure and high temperature

During hydraulic fracturing operations of low-permeability reservoirs,packers are the key component to ensure the success of multistage fracturing.Packers enable sections of the wellbore to be sealed off and separately fractured by hydraulic pressure,one at a time,while the remainder of the wellbore is not affected.However,reliable sealing properties of the packer rubber are required to meet the high-pressure and high-temperature(HPHT)conditions of reservoirs(such as 70 MPa and 170 ℃).In this study,the structures of the packer rubber with two different materials are optimized numerically by ABAQUS and validated by experiments.The optimization process starts from the packer rubber with a conventional structure,and then,the weakest spots are identified by ABAQUS and improved by slightly varying its structure.This process is iterative,and the final optimized structure of a single rubber barrel with expanding back-up rings is achieved.For the structure of three rubber barrels with metallic protective covers,both HNBR and AFLAS fail under HPHT conditions.For the final optimized structure,the packer rubber made of AFLAS can work better under HPHT than that made of HNBR which ruptures after setting.The results show that the optimized structure of a single rubber barrel with expanding back-up rings and the material AFLAS are a good combination for the packer rubber playing an excellent sealing performance in multistage fracturing in horizontal wells.

Analysis of the sealing performance of combined sealing structure under deep-sea high pressure environment

For the requirement of safe and stable operation,the combined sealing structure was used for reciprocating motion in the deep sea high-pressure environment,and the effects of different seawater depths and shaft movement speed on the sealing performance of the combined sealing structure were studied.The change rule of the sealing performance of the combined sealing structure of reciprocating motion under different working conditions is proved.The study shows that in the combined sealing structure of reciprocating movement,the Von Mises stress and the contact stress of the O-ring varies with the direction of the shaft movement.The Von Mises stress and contact stress of the O-ring,the Von Mises stress and the contact stress on each sealing lip of the slip ring gradually increase with the increasing of seawater depths.At the same time,the Von Mises stress of the O-ring which in the process of the shaft upward movement is greater than the shaft downward movement,making the shaft upward movement more likely to cause the O-ring relaxation and fatigue.The shaft movement speed has no significant influence on the Von Mises stress and contact stress of the O-ring.The research results provide theoretical guidance and technical support for the selection and optimization of the geometrical parameters of the combined sealing structure in the deep-sea high-pressure environment.

Nonlinear Finite Element Analysis of the Structure of Door Seals

In order to evaluate the influence of the seal structure on door dosing force, nonlinear finite dement methed is introduced to analyze compression deformation of a door seal for SANTANA （name of the car made by Shanghai Volkswagen Co. Ltd）. MSC. Marc software is used to analyze the large deformation of the seal and the compression test is done to prove the computational results. The results show that the compression loads of the door seal are larger than the standard value of Shanghai Volkswagen Co. Ltd and the seal structure needs to be optimized. There are consistent relationships between calculating results and experimental results and the simulation method is effective.

A full-section asphalt concrete waterproof sealing structure for the high-speed railway subgrade

Purpose–This study aims to investigate the service performances of a new full-section asphalt concrete waterproof sealing structure(FSACWSS)for the high-speed railway subgrade through on-site tracking,monitoring and post-construction investigation.Design/methodology/approach–Based on the working state of the waterproof sealing structure,the main functional characteristics were analyzed,and a kind of roller-compacted high elastic modulus asphalt concrete(HEMAC)was designed and evaluated by several groups of laboratory tests.It is applied to an engineering test section,and the long-term performance monitoring and subgrade dynamic performance testing system were installed to track and monitor working performances of the test section and the adjacent contrast section with fiber-reinforced concrete.Findings–Results show that both the dynamic performance of the track structure and the subgrade in the test section meet the requirements of the specification limits.The water content in the subgrade of the test section is maintained at 8–18%,which is less affected by the weather.However,the water content in the subgrade bed of the contrast section is 10–35%,which fluctuates significantly with the weather.The heat absorption effect of asphalt concrete in the test section makes the temperature of the subgrade at the shoulder larger than that in the contrastive section.The monitoring value of the subgrade vertical deformation in the test section is slightly larger than that in the contrastive section,but all of them meet the limit requirements.The asphalt concrete in the test section is in good contact with the base,and there are no diseases such as looseness or spalling.Only a number of cracks are found at the joints of the base plates.However,there are more longitudinal and lateral cracks in the contrastive section,which seriously affects the waterproof and sealing effects.Besides,the asphalt concrete is easier to repair,featuring good maintainability.Originality/value–This research can provide a basis for popularization and application of the asphalt concrete waterproof sealing structure in high-speed railways.

Multilevel Micro Structures of the Clam Make the Sealing Even Tighter

Excellent fluid sealing performance is crucial to ensuring the safety of important equipment,especially in aerospace field,such as space capsule and fuel chamber.The frequently opening and closing of the sealing devices is particularly important.Driven by this background,clams(Mactra chinensis)which can open and close their double shells with superior sealing performance,are studied in this work.Here,we show that the clam’s sealing ability is the result of its unique multilevel intermeshing microstructures,including hinge teeth and micro-blocks.These microstructures,which resemble gear teeth,engage with each other when the shell closes,forming a tight structure that prevents the infiltration of water from the outside.Furthermore,the presence of micron blocks prevents the penetration of finer liquids.The simulation results of the bionic end seal components show that the multilevel microstructure has a superior sealing effect.This research is expected to be applied to undersea vehicles that require frequent door opening and closing.

Structure of V_2O_5-P_2O_5-Sb_2O_3-Bi_2O_3 glass

The structure ofV2O5-P2O5-Sb2O3-Bi2O3glass and its state of crystallization were studied by means of infrared spectroscopy and X-ray diffraction analysis. The results indicate that, in this glass, V and P exist mainly in the form of a single-stranded linear （VO3）n and an isolated （PO4） tetrahedral with no double bond. Partial V and P are connected through O, forming an amorphous structure of layered vana- dium phosphate. Trivalent Sb3＋ and Bi3＋ open the V=O bond and appear in interlayers, so a weak three-dimensional structure is connected successfully. Along with the substitution of Sb203 for partial V205 or that of P205 for partial V205, the network structure of the glass is rein- forced, and the crystallization is reduced.

Effects of Zn/P ratio on structures and properties of zinc-iron phosphate glasses

Effects of Zn/P ratio on the structures and properties of glasses with the general composition of （80-x）ZnO-20Fe2O3-xP2O5 （x=40, 45, 50, 55, 60） （molar fraction, %） were investigated. Glass structure was measured by infrared absorption spectrum. Glass density （/9） was measured by the Archimedes method. Coefficients of thermal expansion （a） and characterization temperature were obtained by a dilatometer. Water durability of each glass was estimated from the dissolution rate （DR）in water at 90 ℃ for 24 h. With increasing Zn/P ratio, water durability of zinc-iron phosphate glasses increases dramatically without large increase in the characterization temperature. （80-x）ZnO-20Fe2O3-xP2O5 glasses with 0.3≤Zn/P≤0.5 are suit for low-to-mid temperature sealing application for substrates with a〈8.0× 10^-6℃^-1.

基于PTFE矩形密封圈的高压容器密封结构设计

PTFE矩形密封圈具有耐化学性能好、截面稳定性高等优点,可以有效解决腐蚀性介质的密封问题。但在实际使用中,PTFE矩形密封圈及其适配沟槽的尺寸设计缺乏参考依据。针对上述问题,根据高压容器端面密封结构的形状与受力特征,在Ansys Workbench中建立PTFE矩形密封圈的二维轴对称模型,采用双线性等向强化模型表征PTFE的力学性能,对基于PTFE矩形密封圈的高压容器端面密封结构进行分析和设计,讨论压缩率、PTFE矩形密封圈几何参数和沟槽结构参数对高压容器端面密封性能的影响。结果表明,压缩率、矩形圈的高度和宽度以及矩形圈与沟槽侧壁的间隙对密封性能的影响较大,而内径对密封性能的影响较小,因而设计时应优先考虑沟槽深度、矩形圈的截面尺寸以及与沟槽的装配位置等参数。确定PTFE矩形密封圈及适配沟槽的尺寸后,采用有限元仿真手段验证了设计的密封结构在常温30 MPa高压下的密封性能,证实了设计的合理性。

超高压压裂管汇由壬接头预紧特性分析

针对超高压压裂管汇由壬接头安装预紧力不当导致结构破坏或密封泄漏的问题,以某公司研制的175 MPa超高压由壬接头为研究对象,利用ABAQUS建立由壬接触模型,采用有限单元法对该接头进行应力分析与强度评定以及密封性能判定。结果表明:预紧力大小对母由壬应力几乎没有影响,对公由壬、翼型螺母和三瓣挡圈应力有显著影响,且都呈现正相关性,影响程度从高到低依次为公由壬、翼型螺母、三瓣挡圈和母由壬;额定工况下预紧力超过250 kN时,公由壬轴肩圆角处应力超过其材料许用应力,结构静强度不满足要求可能会发生结构破坏;预紧力小于150 kN时,不足以抵抗内压作用,公由壬和母由壬球头锥面密封结构分离;在能够确保球头锥面密封性和结构安全性的150~250 kN预紧力范围内,氢化丁腈橡胶(HNBR)密封圈表面接触应力始终大于实时流体工作压力,密封圈密封性能良好。推荐安装预紧力范围为150~250 kN,在该范围内密封圈结构的静强度以及密封性均能满足要求。

铋酸盐封接玻璃的研究及其连接应用现状

无铅低温封接玻璃由于具有绿色安全、成本低、封接温度低等优势,被广泛应用于航空航天、电真空、集成电路等领域。在磷酸盐、钒酸盐、硼酸盐和铋酸盐等多种封接玻璃体系中,因铋与铅具有相似的性质特点,使得铋酸盐玻璃成为最有可能替代铅酸盐玻璃的绿色玻璃钎料。综述了铋酸盐玻璃的成分和性能调控、网络结构的研究现状,介绍了目前使用铋酸盐封接玻璃进行金属、陶瓷同质/异质材料连接的研究进展,最后对未来的发展趋势进行了展望。

俄罗斯液体潜射弹道导弹长期贮存材料工艺技术

对液体潜射弹道导弹长期加注贮存技术的发展进程、最新进展及研究现状进行概述。重点介绍俄罗斯液体潜射弹道导弹的结构设计、材料选取和制造工艺以及出厂加注封装和密封性检测方法,最后指出实现长期加注贮存的技术路径。

结构参数对液压旋转接头密封性能的影响

为探究结构参数对液压旋转接头间隙密封性能的影响规律,分别以泄漏量和压力损失作为液压旋转接头的性能指标,研究密封有效长度、密封直径、密封间隙值3种主要结构参数对旋转接头性能的影响。采用正交试验与Fluent流体仿真相结合的方法,分析液压旋转接头间隙密封在不同结构参数下的泄漏量和压力损失情况。结果表明:3种结构参数对泄漏的影响程度由大到小依次为密封间隙值、密封有效长度、密封直径,对压力损失的影响程度由大到小依次为密封有效长度、密封直径、密封间隙值;密封间隙值大小对泄漏量影响非常显著,泄漏量随着间隙的增大呈指数增长关系,而间隙密封有效长度、环形密封直径对泄漏量无显著影响;密封有效长度对压力损失有极其显著影响,而密封直径和密封间隙值对压力损失没有显著影响;从整体上看密封间隙值、间隙密封直径、密封有效长度都大致与压力损失呈一次函数关系,且前两者与压力损失呈正相关关系,后者则与压力损失呈负相关关系。

基于热流固耦合的液膜密封动态追随性分析

为研究热流固耦合下液膜密封动态追随特性,基于小扰动法及热动力润滑理论,考虑非补偿环轴向振动、角向偏摆,建立补偿环三自由度运动方程,对比并分析纯流场和热流固耦合模型下力学元件参数、操作工况参数、结构参数对动态追随性的影响。结果表明:在热流固耦合模型下求解的液膜密封扰动量略小于纯流场模型下求解的扰动量;增加激励振幅,弹簧刚度和O型圈阻尼均会导致扰动增大,动态追随性变差;减小转速、增加介质压力会导致动态特性系数增加,有利于提高动态追随性;减少槽数会提高动态追随性,且在槽数给定时,槽深17μm,槽坝比0.8,螺旋角22°的结构参数设定会得到更好的动态追随性。

流量控制阀K形金属密封圈结构参数优化

流量控制阀K形金属密封圈结构参数较多,且不同结构参数对密封性能影响程度存在较大差异。以密封面接触压力、密封面有效接触长度及最大Mises应力为约束条件,采用正交试验设计研究影响K形金属密封圈密封性能结构参数之间的主次关系,确定了唇部长度、悬臂内张角与悬臂厚度3个因素作为响应曲面法的设计变量;通过正交试验和回归分析得到接触压力、最大等效应力及有效接触长度与设计参数关系的二次回归方程,并基于响应面法对密封结构进行优化分析。优化后K形金属密封圈的接触压力增加了8.09%,有效接触长度增加了14.73%,最大等效应力减少了13.44%,表明优化后K形金属密封圈密封面接触压力分布更加均匀,有效提高了金属密封圈的密封性能。

川东地区高陡构造带寒武系洗象池群天然气成藏条件

利用岩心、测井与地震资料,采用地震解释、平衡剖面以及包裹体检测等技术,恢复了川东地区高陡构造带的构造演化史,并对平桥、建南、梓里场构造的天然气来源、运聚与保存条件进行了分析。研究结果表明:(1)川东地区平桥断背斜圈闭东翼的单条逆断层使得下盘的龙马溪组烃源岩与上盘的洗象池群储层发生了侧向对接,天然气可穿过断裂带向上盘储层运移,具备较好的输导条件,且圈闭盖层未受到断裂作用破坏,保存条件良好,有利于天然气的聚集成藏。(2)建南断背斜圈闭翼部的多条平行的逆断层虽然实现了部分源-储对接,但是多条断层组合降低了其侧向输导能力,天然气未能大规模聚集。(3)梓里场断背斜圈闭的源-储配置与输导条件优良,但盖层的封盖能力较差,大多被断层破坏,钻探显示储层为水层。(4)川东地区高陡构造带寒武系洗象池群天然气聚集成藏的主控因素包括:断层或断层组合控制下的源-储配置、侧向输导条件以及盖层的封盖能力。

基于MBD的航空橡塑密封结构案例库构建

为有效积累和重用航空橡塑密封结构案例中蕴含的知识,提出基于模型的定义(Model Based Definition,MBD)的航空橡塑密封结构案例库构建方法。首先,基于航空橡塑密封结构行业设计标准和MBD的三维建模与标注方法,建立基于MBD的航空橡塑密封结构案例内容框架和表示,通过SolidWorks MBD模块实现航空橡塑密封结构案例的MBD表示;然后,提取航空橡塑密封结构MBD案例表示中的几何特征和语义特征,设计“几何+语义”的案例检索算法;最后,开发的基于MBD的航空橡塑密封结构案例库原型系统及其应用表明,基于MBD的航空橡塑密封结构案例表示与检索实现了知识的积累和重用。

基于有限单元法密封结构影响因素建模分析

密封圈结构对高压试验装置的密封性、承压性具有直接影响。依据高压试验装置的结构特点,对O型密封结构进行结构参数分析,基于Mooney-Rivlin模型对特性进行分析;利用MARC有限元分析的方法对O型圈进行密封分析,分析不同密封间隙和槽深的尺寸下,接触压应力和Von Mises应力的大小,基于分析结果,优选密封间隙和槽深参数。结果可知:密封间隙为(0.04~0.14)mm间,压缩率为(10~20)%间,能够满足设计承载条件下的密封要求;通过对影响因素分析发现,密封间隙与Von Mises应力正相关,与接触应力负相关;压缩率提升,Von Mises应力先增后降,最大接触应力先降后增;80MPa压力下,较小密封间隙、压缩率对密封结构承载是有利的;通过分析设计密封圈影响趋势,发现参数的最优解为间隙0.043mm,槽深5.357mm,压缩率为10%。分析方法和研究结果可为超高压压力容器O型密封结构设计提供参考依据。

衍生T形槽干气密封稳态性能研究

目的 设计具备双向旋转特点的动压型干气密封端面结构,并展现良好的开启性能,以T形槽为优化对象,衍生出一种新型槽型结构。方法 借助有限元软件,计算并对比经典T形槽与衍生槽型在流场特性和稳态性能方面的差异,探讨不同参数对2种槽型干气密封稳态性能的影响规律,揭示衍生槽型的密封机理。结果 衍生槽型的开启力高于经典T形槽,泄漏率也会增加。随着工况参数的升高,2种槽型的稳态性能参数近似线性增加,且差异逐渐增大,最小差异达到6.6%。随着槽深的增加,泄漏率方面的差距在逐渐减小,为扩大衍生槽型的控漏效果,槽深应>5μm。开设有引流槽型结构的衍生槽型稳态性能顺序为发散型>直口型>收敛型,但在文中的工况下,数值差别较小,最大仅为1.2%。结论 相比于经典T形槽,衍生槽型具有更强的动压效应,开启性能明显提升。另外,通过开设不同形式的引流槽可以改变气膜的流动特性和干气密封性能。

基于Workbench的瑞利台阶干气密封流固耦合分析

为了研究瑞利台阶在干气密封中的性能表现,建立了瑞利台阶干气密封计算模型,采用Workbench流-固耦合分析模块对动、静环在整体气膜作用下的受力与变形进行模拟计算,探究了不同工况参数和密封环材料对动、静环的变形及应力影响规律。结果表明:在槽根处的气膜压力最大,形成的动压效应最强,气膜力也较大,故动、静环的最大应力和形变均位于槽根处。在入口压力和旋转速度增大时,气膜力也会随之增大,从而使动、静环的应力值和形变量增大。动环材料相对于静环材料有更高的弹性模量,所以动环的应力变化相对于静环要更大,而较大应力变化有利于抵消流体力耦合引起的变形应力,进而达到减小密封环变形的目的。

液压排气阀特种卡帽注射模具设计与CAE分析

介绍了一种液压排气阀特种卡帽,内部采用异型卡位设计,外侧采用长尾柄结构,既有利于按压排气、也可以快速旋转,采用聚甲醛(poly for maldehyde, POM)材料,能保持较高的热稳定性和抗老化性能。在制造过程中,设计了一种全新的一模两腔的热流道哈弗块侧抽芯模具结构,经CAE分析产品的细节特征,在哈弗块上设置了隔水板冷却水路,内部型芯也设置了隔水板水路,提高了模具冷却效率,运用CAE软件模拟了产品的填充与冷却过程。经试模验证,该模具结构紧凑,塑件质量稳定、精度高,开合模动作合理可靠,制品顺利脱模,可有效节约成本,缩短了产品成型周期,提高了产品的生产率,产品能完全达到客户要求,为同类型产品提供了良好的解决方案。