迷宫密封的湍流增阻

迷宫密封是依靠节流间隙中的节流过程和迷宫空腔内的动能耗散过程来实现密封的,这两个流体流动过程从本质上规定了迷宫密封的密封性能。通过密封内部流动本质的研究,可以利用湍流流动的一些规律和特点,发挥密封内部湍流的增阻作用,提高密封性能。通过对一种锯齿形迷宫密封的数值和试验研究,揭示了湍流惯性偏转和射流收缩在湍流增阻中的作用。利用这些湍流增阻的原理,可以突破节流间隙的微小尺寸限制,实现较大间隙下的良好密封,这不仅会给迷宫密封的制造、安装及运行等带来很大的方便,而且可以为发展新的迷宫密封理论奠定理论基础。     

基于FLUENT的迷宫密封机理研究

针对影响迷宫密封泄漏特性的三个因素:间隙宽度、齿型夹角以及空腔深宽比,计算了不同结构的内部流场,探讨了各因素对泄漏特性的影响,分析了密封机理。结果表明:迷宫密封的泄漏量随间隙的增大而增大,并得到满足泄漏量条件的最大间隙宽度cmax≈0.57mm;在一定深宽比下,存在最佳齿型角度,随着压比的增加,最佳齿型角度的影响加大;空腔深度和空腔宽度之间存在最佳匹配关系,且空腔深宽比不随间隙宽度的变化而变化。     

迷宫密封机理的研究现状及其展望

分别从泄漏量的计算方法、密封性能的影响因素以及迷宫密封内部流场机理的研究等方面介绍了迷宫密封机理的研究现状,并分析了目前研究中存在的不足,简要地探讨了迷宫密封机理研究的发展方向.     

迷宫密封的间隙研究

从转子静挠度、经向跳动、轴承偏心值及转子热变形等四个方面讨论了理论间隙的影响因素。重点研究了迷宫密封半径间隙的计算问题。指出了在密封设计上的注意事项。     

径向错齿式迷宫密封设计浅析

从总体布局、节流间隙宽度的确定、节流齿数的选取及腔形状的确定等四个方面，介绍了结构设计原则。阐述了泄漏速率的计算方法。最后做了几点说明。     

类迷宫螺旋密封与迷宫密封的性能对比研究

往复式压缩机迷宫密封加工过程中,为简化加工工艺,将传统迷宫密封加工成类迷宫螺旋密封。为比较类迷宫螺旋密封与迷宫密封的密封性能差异,分析类迷宫螺旋密封的密封机制,将类迷宫螺旋密封的能量耗散分成类迷宫密封能量耗散和槽向能量损失,采用CFD方法对类迷宫螺旋密封的密封性能进行数值模拟。结果表明,类迷宫螺旋密封的密封性能虽不及传统迷宫密封,但密封效果相差在5%以内,综合考虑加工工艺、经济效益等因素,采用类迷宫螺旋密封代替迷宫密封是完全可行的。     

径向迷宫密封泄漏速率计算方法的分析

对现有径向迷宫密封漏速率计算方法的理论论导出原理，公式特点，使用方法及其适用特性进行了综合论述，可供有关设计人员参考。     

径向错齿式迷宫密封空腔形状的试验研究

对直角形节流齿的径向错齿式迷宫密封空腔形状进行了试验研究,得出空腔深度与宽度之间最佳比例关系值(T/S)_(opt)约为1.1～1.3,此结果与轴向直通式迷宫密封已有成果有明显的不同;并对节流间隙、压力状态、空腔宽度及流动方向等对(T/S)_(opt)值的影响进行了探讨。     

涡旋压缩机的径向迷宫密封研究*

针对涡旋压缩机径向密封难以实现的难题,提出一种径向迷宫密封。用几何学和热力学方法证明基圆渐开线型涡旋压缩机径向光滑间隙密封中的泄漏气速达到声速,分析径向光滑间隙密封中泄漏气体的热力变化过程,根据临界截面上气体的气动热力特性,推导出考虑边界层摩擦损失的径向光滑间隙密封泄漏量的算法,根据能量方程和连续性方程,推导出判定径向迷宫密封中泄漏气速是否达到声速的判别式和径向迷宫密封泄漏量的算法。计算和实测两种密封在一系列相邻压缩腔压差对应下的泄漏量。理论计算和试验对比表明,给出的两种密封泄漏量的算法正确;径向光滑间隙密封和径向迷宫密封的泄漏量均随着相邻压缩腔压差的增大而增大;径向迷宫密封的直通效应随着相邻压缩腔压差的增大而更加明显;径向迷宫密封泄漏量实测值约为径向光滑间隙密封泄漏量实测值的79%,说明径向迷宫密封的密封性能优于径向光滑间隙密封的密封性能。     

径向错齿式迷宫密封泄漏速率的计算

对径向错齿式迷宫密封泄漏速率的计算公式进行了分析和论证；用大量实验数据逐步回归分析获得了在一定结构条件下的迷宫系数计算公式。经实验验证，该计算方法的相对误差小于４％。     

径向迷宫密封泄漏特性的数值预报

基于迷宫密封内部流场的数值模拟,提出了一种径向迷宫密封泄漏特性的数值预报模型,并对一种径向锯齿型迷宫密封的泄漏特性进行了实例预报,预报结果与实验结果吻合较好.     

活塞式制冷压缩机活塞与汽缸间隙迷宫密封的理论研究

对活塞式制冷压缩机工作过程进行了数值模拟,建立了活塞与汽缸迷宫密封的数学模型,分析了泄漏量随活塞与汽缸间隙及迷宫槽间距变化的关系.     

Experimental and Numerical Assessment of an Advanced Labyrinth Seal

A previously validated finite difference computer model for seal leakage was used in developing an advanced seal with reduced leakage. A new design feature is an annular groove judiciously located in the stator housing. A detailed assessment of this preliminary groove configuration was conducted, both experimentally and computationally. It was found that the presence of the particular groove considered here contributes an approximately 20 percent decrease in leakage, while introducing no shaft speed effects. To enhance physical insight, detailed computed distributions of streamlines are included. Further, the interesting measured effect of the relative axial position of the rotor/stator sealing surfaces on leakage rate and stator wall axial pressure distribution is examined.     

螺旋密封气吞及密封失效机理分析

本从泵的角度对螺旋密封“气吞”及“密封失效”现象作出了合理,全面的解释,并提出一种新型组合螺旋密封,分析结果表明,转速较高时,迷宫螺旋密封优于组合螺旋密封,优于单一结构螺旋密封,具有一定的工程使用价值。     

盘缘篦齿封严特性的数值模拟

为了解航空发动机空气系统中盘缘篦齿的流动及封严情况,采用数值模拟方法对二维盘缘篦齿封严特性进行了系统的研究。使用商业软件FLUENT 6.3对不同的盘缘篦齿齿数N、轴向间隙s和径向间隙d分别进行了计算,得出了在各种情况下泄漏系数随转速的变化关系,主要结论为:转速对篦齿封严的影响不明显;两个齿的封严效果比单个齿的好;相同的径向间隙d下,轴向间隙s越大,封严效果越好;相同的轴向间隙s下,径向间隙d越小,封严效果越好。     

Effect of Rub-Groove Wall Angle on the Leakage of Abradable Stepped Labyrinth Seals

Rub grooves are generally formed in gas-turbine labyrinth seals of the abradable type during various transients. The rub-groove shape, often the slope angle of the groove downstream wall, varies and largely depends on the rotordynamics and the thermal expansion rates of the rotor and the stator. The effect of rub-groove shape on stepped labyrinth seal leakage was studied by varying the slope angle of the groove downstream wall, using various tooth axial positions and various prerub radial clearances. The investigation was done for compressible flow, with air as the working fluid. A finite volume method was used to solve the two-dimensional axisymmetric, Reynolds-averaged Navier-Stokes equation system. The high-Reynolds-number k-? turbulence model was used along with wall functions. It was found that the wall angle of rub groove has a significant effect on the leakage as well as on the flow pattern. For the cases considered here, when the seal operates with the tooth positioned axially within the rub-groove axial width, the leakage decreases with an increase of the rub-groove downstream wall slope angle. However, for operation when the tooth lies axially just downstream of the groove, the leakage is slightly increased with an increase of the rub-groove wall angle. For cases with a certain tooth axial position and prerub radial clearance, a small change of groove sloping wall angle results in a large change in flow pattern.     

CFD Study on Stepped and Drum Balance Labyrinth Seal

The stability of rotors in turbomachines is affected by the labyrinth seal where driving forces are generated. Recent research results have shown that the preswirl has a significant influence on the rotordynamic characteristics of the straight labyrinth seal including both tooth-on-stator and tooth-on-rotor configurations. However, modern turbomachines require higher and higher pressure drop for the seal so that the eye seal is usually designed as stepped labyrinth, whereas the balance drum usually employs a tooth-interlocking labyrinth and a larger number of teeth. Both designs could generate greater forces on the rotor than the straight labyrinth seal. Therefore, it is necessary to further study the influence of preswirl on stepped and tooth-interlocking labyrinth seals. This article employed 3D calculational fluid dynamics (CFD) to solve the flow in those seals. Then the rotordynamic coefficients of the two seals at different preswirl rates were calculated based on the CFD results. The results were compared with test data and bulk flow results. A rotor stability analysis was conducted considering the balance drum seal with the coefficients predicted by the numerical method.     

Performance of a Complaint Foil Seal in a Small Gas Turbine Engine Simulator Employing a Hybrid Foil/Ball Bearing Support System

Operation of a non-contact compliant gas foil seal (CFS) in a high temperature hybrid dynamic simulator representative of a small gas turbine engine spool is discussed. At the hot section of the simulator two oil-free components, a CFS and a compliant foil bearing (CFB) were mounted and at the cold (compressor) section of the simulator, an oil-mist lubricated ball bearing was installed. The preliminary numerical study on the fluid flow and thermal analysis of a CFS was discussed in the previous work by the authors. The experimental results for successful operation of the foil bearing and foil seal at temperatures up to 560 °C and speeds up to 55,000 rpm are presented. The surface of the CFS and CFB journals for high temperature tests were coated with PS304 solid lubricant film, developed by NASA The CFS performance at different operating speeds and temperatures and differential pressures was investigated. In a similar test, a leakage flow comparison was made among a labyrinth seal, a brush seal and a CFS. The experimental results indicate superior performance of the CFS over the two other types of seals. Unlike brush seal, CFS showed no evidence of rub or induced wear on the journal or seal surface.     

软填料密封机理分析

软填料密封结构简单,历史悠久而应用广泛,但对被密封流体通过软填料密封的泄漏机理和软填料密封的密封机理并没有完全认识清楚。本文初步分析了流体通过软填料密封的泄漏机理和使软填料密封具有良好密封性能的基本要求,并澄清了有关软填料密封机理的一些模糊认识。     

电流变体在密封中的应用研究

本文根据电流变体在一定电压状态下所具有的固化特性，将电流变体开发诮地密封装置中以解决工程实际中流体系统的密封问题。试验表明电流变体在密封中应用具有一定的潜力。本文的研究为电流变体的工程应用开拓了一个新的领域。