错齿式迷宫密封流场及泄漏量的数值分析

以某型大功率机车传动齿轮箱轴端迷宫密封为研究对象,采用GAMBIT软件建立错齿式迷宫通道的二维结构化网格模型,应用FLUENT软件模拟迷宫密封腔内流场分布及泄漏特性,分析转速、压比、空腔尺寸对迷宫密封性能的影响.研究结果表明:泄漏量随着进出口压比的增加而增加;转速对泄漏量影响很小;空腔尺寸对密封性能的影响较大.     

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。     

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。     

考虑齿变形的迷宫密封泄漏特性流固耦合数值研究

为研究非金属热塑性材料的迷宫密封齿变形对密封性能的影响,建立考虑齿变形的迷宫密封泄漏特性瞬态流固耦合数值求解模型,在验证数值求解模型准确性的基础上,分析不同进出口压比下,酚酞聚芳醚酮(PEKC)、聚醚醚酮(PEEK)、聚醚砜酮(PPESKca30)3种材料的迷宫密封力学特性及泄漏特性.研究结果表明:考虑齿变形的密封流场...     

密封齿对侧开槽对迷宫密封泄漏特性的影响

为了降低迷宫密封的泄漏量,提出一种在直通型迷宫密封的密封齿前端和后端设立凹槽的密封结构,基于CFD方法,建立迷宫密封数值仿真模型。通过与已有试验数据的对比,验证模型的正确性。探讨不同湍流模型的适用范围,并对比光滑表面、前置凹槽、后置凹槽3种结构在泄漏量、轴向压降及流场速度分布的差异性。结果表明:SST湍流模型更加适用于迷宫密封这种窄间隙的近壁面流动;前置凹槽结构降低泄漏量的效果较差,只有在高压力差下才能降低泄漏量;后置凹槽结构能改变迷宫密封腔内漩涡方向及状态,进而降低迷宫密封透气效应,加剧密封的能量耗散的同时降低泄漏量。因此,后置凹槽的迷宫密封结构具有较好的工程应用前景。     

厚齿直通式迷宫密封静态工作特性的实验研究

本文所述的实验工作是围绕着直通式迷宫密封的应用技术基础问题而展开的,建立了迷宫密封的静态实验研究,首次全面地研完了厚齿条件(T/δ≥4)下的各种结构参数对密封效率的影响,指出了齿尖相对厚度T/δ,空腔数N,间隙与宝腔的宽度之比δ/W,以及空腔的深宽比H/W等参数的影响规律。     

迷宫密封齿角对动力特性系数的影响

由两控制体方法建立密封齿角变化时气流激振基本方程式,用摄动法得到密封齿角变化时的动力特性系数。结果表明：必须考虑密封齿角对转子动力特性系数的影响,角度越大,影响越大,尤其是负预旋时更加明显。本研究对于进一步理论研究以及实际密封结构设计有重要的指导意义。     

多变量双侧齿迷宫密封泄漏量模拟分析研究

针对目前主要以单侧齿、单一变量变化研究迷宫密封泄漏量所存在的不足,本文以多变量函数理论为基础,以双侧齿迷宫空腔结构多参数变化对迷宫密封性能影响为研究对象,对双齿侧、双变量变化的迷宫密封泄漏量进行研究。通过对迷宫密封流场中三角形齿和矩形齿的深宽比、密封间隙、齿数等参数变化的模拟研究表明,本文所提出的方法与原计算方法相比,计算精度高3%⁵%。     

齿型夹角对迷宫密封性能影响的数值研究

FLUENT软件对相关文献的实验模型进行数值计算,证明了所用计算方法的可靠性。模拟计算了6种不同等腰梯形齿的迷宫流场,并分析其密封机制,探讨了梯形齿夹角的变化对泄漏特性的影响。研究结果表明:当其它结构尺寸一定,随着梯形齿夹角的增大,迷宫密封的泄漏量减小,存在着最佳角度使得泄漏量最小;同一齿型角,在不同压比下,对泄漏系数的影响程度是不同的;不同齿型角,在不同压比下,对泄漏系数的影响程度也是不同的,随压比的增加,影响程度增加,如:齿型角为47°相比齿型角为20°结构,在压比为1.5和3.0时,泄漏系数就分别减小0.804%和1.63%。     

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.     

Effect of Axially Grooved Oil Seals on the Leakage Flow and Stability of a Centrifugal Compressor

The results of an analytical investigation are given for the effect of axially grooved floating oil ring seals on the leakage flow and stability of a centrifugal gas compressor. The finite element method was used to solve the non-linear and coupled hydrodynamic and thermal equations for pressure and temperature distributions in the oil seal ring with and without the axial grooves. The peturbation technique was used to obtain the static and dynamic characteristics of the oil seal. The results for selected cases of axial grooving are presented in graphical form for operation at various eccentricities. The non-dimensional leakage flow results correlate well with previously published results calculated by narrow groove theory. The stability of a multi-stage gas compressor is evaluated for different configurations of the oil seal grooving geometry. The compressor rotor shaft finite element model includes a multi-level analysis for the oil seal rings that permits the evaluation of the floating seal influence on the total system stability. Results are given for both low and high-pressure sealing conditions, which simulate test stand and field operating conditions. The results show that the added grooves enhance the stable operation of the rotor system for low-pressure fixed seal conditions arid reduce the system stability at lower eccentricities for low-pressure floating seal conditions. In high pressure conditions the added grooves enhance the stability of the system for both fixed and floating seal conditions.     

迷宫密封中可压流体流场的数值模拟

应用Fluent软件计算迷宫密封间隙宽度和空腔深度以及直通式迷宫密封和错列式迷宫密封对迷宫密封流场和泄漏量的影响。计算结果与分析表明,间隙宽度对泄漏量的影响体现在通过改变空腔进出口面积来改变泄漏量。所以泄漏量随间隙宽度呈线性变化。在实际运用中,在保证安全的情况下尽量减小间隙宽度;在一定条件下,空腔深度越大,紊流程度下降,泄漏量越大;错列式迷宫密封的泄漏量要明显小于直通式迷宫密封。     

迷宫密封动力特性影响因素分析

迷宫密封的存在会引起汽流激振,密封的结构和工况参数对转子动力特性均存在影响。本文综合分析转子转速、入口预旋比、密封间隙、压差等因素对转子动力特性系数的影响,为迷宫密封汽流激振的防治和设计中各参数的最优确定提供参考依据。     

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.     

环形密封整体流动模型流场解的改进

提出了零阶摄动解的一个改进算法。用通过解析延拓加上周期性条件的三次样条方法取代复快速Ｆｏｕｒｉｅｒ变换方法求周向梯度,用递推关系式算法取代解线性代数方程组。改进算法提高了计算效率,保证了计算准确度。此外,在收敛到零阶出口压力边界条件时,构造了较易收敛的减缩修正方法。     

Experimental Study on the Sealing Mechanism of Bidirectional PTFE Lip Seals

Seals made of polytetrafluorethylene (PTFE) are resistant to heat and chemicals and can run dry, but they do not pump back fluid. PTFE lip seals with a spiral groove do pump back fluid but only in one rotational direction. PTFE lip seals for both rotational directions (bidirectional) are not available on the market. At the Institute of Machine Components (IMA) of the University of Stuttgart, PTFE lip seals with bidirectional sealing aids were developed and analyzed. During the research, the leak-tightness in static and dynamic conditions was continuously improved. The latest design is leak-tight in both rotational directions. The sealing mechanism for this design is explained. The resulting seals can be used in conditions where elastomeric lips seals will fail.     

透平压缩机迷宫密封泄漏量的数值仿真研究

给出了适用于透平压缩机迷宫密封泄漏量的修正模型,并用修正模型对变结构参数下的泄漏量进行规律研究.通过采用工程常用迷宫密封泄漏量理论公式,计算了不同压比下透平压缩机典型平滑型和曲折型迷宫密封流量系数,对比了试验结果,修正了流量系数值;在此基础上,进一步研究了不同间隙和齿数下泄漏量的规律,以研究参数变化对泄漏量的影响.研究结果表明:对于平滑型密封结构,修正模型的修正系数可选择在0.8~1.2;对于曲折型密封结构,修正模型的修正系数可选择在0.7~0.8.本文提供了一种较为准确、工程性的透平压缩机迷宫密封泄漏量模型的修正系数.     

燃机曲折型迷宫密封的泄漏特性研究

以F级燃气轮机中曲折型迷宫密封为研究对象,对其内部流场和泄漏特性进行数值模拟,研究密封间隙、压比对迷宫密封泄漏特性的影响。结果表明：在相同密封间隙下,泄漏量随着压比的提高而增加;相同压比下,泄漏量随着密封间隙的减小而减少。基于数值计算结果,对现有迷宫密封泄漏量计算公式进行修正,建立曲折型迷宫密封的泄漏量计算公式。该公式计算结果与CFD数值模拟结果吻合很好,和同类公式相比,能够更为精确地计算该类型密封结构的泄漏量。