ACOUSTIC ANALYSIS OF HYDRODYNAMIC AND ELASTO-HYDRODYNAMIC OIL LUBRICATED JOURNAL BEARINGS

The purpose of the present paper is to investigate the effect of elastic deformation of bearing liner on the acoustic behavior of oil lubricated journal bearings.Analysis is performed for hydrodynamic(HD) and elasto-hydrodynamic (EHD) lubrications.Dynamic behavior and acoustical properties are investigated through an analysis of pressure fluctuation calculated from the Reynolds equation governing the flow in the clearance space of the journal bearing.This is solved numerically using the finite difference method with the successive over relaxation technique.In elasto-hydrodynamic lubrication,the finite element method with in iteration scheme is adopted to solve both Reynolds equation and the three-dimensional elasticity equation representing the displacement field in the bearing shell.The results show that the sound pressure level of the bearing is markedly influenced by the flexibility of the bearing liner,the viscosity of lubricant and the load applied to journal.HD analysis shows that the journal centre’s orbit,from a disturbed position,converges to the static equilibrium position faster than EHD lubrication.The results of the present paper could aid in the design of low-noise rotor-bearing systems supported by oil lubricated journal bearings.     

OPERATOR-SPLITTING METHOD FOR ANALYSIS OF CAVITATION IN LIQUID-LUBRICATED HERRINGBONE GROOVED JOURNAL BEARING

ＮＯＭＥＮＣＬＡＴＵＲＥｃ　ｒａｄｉａｌｃｌｅａｒａｎｃｅｈ　ｆｉｌｍｔｈｉｃｋｎｅｓｓ ｈ　ｄｉｍｅｎｓｉｏｎｌｅｓｓｆｉｌｍｔｈｉｃｋｎｅｓｓ (ｈ/ｃ)Ｌ/Ｄ　ｒａｔｉｏｏｆｌｅｎｇｔｈｔｏｄｉａｍｅｔｅｒｐ　ｆｉｌｍ ｐｒｅｓｓｕｒｅｅ　ｅｃｃｅｎｔｒｉ     

NUMERICAL RESEARCH ON WATER GUIDE BEARING OF HYDRO-GENERATOR UNIT USING FINITE VOLUME METHOD

With the consideration of the geometry of tilting pad journal bearing, a new form of the Reynolds equation was derived in this article. The film thickness, the squeeze motion of the journal and the rotation motion of the pad were explicitly contained in the equation. Based on this equation, together with the equilibrium equation of pad pivot, the water guide bearing used in the Gezhouba 10 F hydro-generator unit was numerically researched. The new Reynolds equation for the lubricating film was solved using Finite Volume (FV) discretization, Successive Over-Relaxation (SOR) iteration method and C code are included. According to the numerical solution, and the stability of the film and the influences of the film thickness, the journal squeeze effect and the pad rotation effect on film force were discussed. The results indicate that the squeeze effect can not be neglected, although the rotation effect is negligible for both low-speed and high-speed bearings, so the computing time could be greatly reduced.     

温粘效应下椭圆瓦轴承动特性系数一维模型算法分析

该文建立了轴向解析、周向有限元压力分布的一维变粘度场有限宽椭圆瓦轴承动特性系数模型.忽略泊肃叶流项对速度的影响,不考虑轴向温度变化并沿径向方向积分,三维能量方程可降阶为平均温度场只沿周向分布的一维形式,与雷诺方程解耦.采用一维直接解法求解雷诺方程和轴承在平衡点的挠动和速度方程.既考虑了温粘效应对轴承动力学性能的影响,又提供了无需迭代确定油膜破裂边界和求解油膜力和动特性系数快速算法.作为应用,对进油槽位于水平两侧的椭圆瓦轴承进行了动力润滑热效应分析,与工程数据比较,计算结果稳合,证明该模型合理,适用于工程上多瓦轴承的分析计算.     

基于FLUENT的小雷诺数下方柱绕流的数值模拟

采用FLUENT对小雷诺数（Re〈52）下方柱绕流进行数值模拟,分析方柱后对称反向漩涡的图谱与漩涡尺寸的特点,分析研究表明：在小雷诺数下,方柱绕流的图谱与圆柱绕流图谱相似,并存在两个特征雷诺数,但两个特征雷诺数较圆柱绕流的小些;方柱绕流对称反向漩涡尺寸与雷诺数呈线性关系变化,并且漩涡发生得比圆柱绕流更为剧烈;方柱绕流柱体后的漩涡能够较容易达到稳定状态。研究结论进一步丰富方柱绕流问题。     

穿越城区隧洞分离式衬砌承载机理及性能优化研究

近年来我国兴建的穿越城区引水隧洞工程采用了一种新型分离式衬砌,但其承载机理尚不够明晰。以某水资源配置工程中穿越城区的TBM施工输水隧洞为对象,建立输水隧洞分离式衬砌整体三维有限元数值模型,分析了衬砌的变形、受力和承载比等特征。结果表明：设计内压作用下,钢衬和自密实混凝土径向紧密贴合,排水板铺设范围内两者径向变形明显大于管片,排水板铺设范围外三者径向同步变形,钢衬应力水平低且分布极不均匀,管片应力超过抗裂限值,内水压主要由围岩承担,钢衬承载比例明显低于预期;降低钢衬-自密实混凝土界面、自密实混凝土-管片界面的摩擦系数,均能使钢衬应力分布的均匀性增加,有利于钢衬承载性能的发挥,且对管片抗裂有利;提高排水板厚度与综合模量比值d/E,可以提升钢衬承载比,控制d/E在12.4～45.1 mm³/N范围内,可以满足钢衬容许应力和管片抗裂设计的要求,同时使分离式衬砌钢衬主要承担内水压的设计理念得以实现。     

THE ANALYSIS OF THE TREE－DIMENSIONAL ELASTOHYDRODYNAMIC LUBRICATIONFOR HEAVILY－LOADED FINITE JOURNAL BEARINGS IN NON－NEWTONIAN LUBRICANTS

ＴＨＥ　ＡＮＡＬＹＳＩＳ　ＯＦ　ＴＨＥ　ＴＲＥＥ－ＤＩＭＥＮＳＩＯＮＡＬ　ＥＬＡＳＴＯＨＹＤＲＯＤＹＮＡＭＩＣ　ＬＵＢＲＩＣＡＴＩＯＮＦＯＲ　ＨＥＡＶＩＬＹ－ＬＯＡＤＥＤ　ＦＩＮＩＴＥ　ＪＯＵＲＮＡＬ　ＢＥＡＲＩＮＧＳ　ＩＮ　ＮＯＮ－ＮＥＷＴＯＮＩＡ...     

微极性流体润滑剂的螺旋槽径向轴承动力特性

本文采用算子分裂／有限元法解广义雷诺方程，研究微极性流体润滑剂的螺旋槽径向轴承承载力、摩擦阻力特性。油膜空泡采用全润滑区质量守恒的Elrod算法。微极性流体的粘弹特性由耦合数和分子特征长度两个参数决定。计算结果显示：(1)高耦合数的微极性流体螺旋槽径向轴承比一般牛顿流体为润滑剂的轴承具有较高的承载力，摩擦阻力略有增加。(2)在高耦合数条件下，润滑油膜厚度和微极性流体分子特征尺度的比值越小，轴承的承载力和摩擦阻力越大。本文研究表明，选用合理参数的微极性流体为润滑剂，可以提高螺旋槽径向滑动轴承的承载力。     

偶应力流体有限长径向轴承润滑特性分析

本文从具有偶应力的不可压缩流体基本方程出发,采用润滑层的通常假设,求得了流体速度的解析表达式,并推导了偶应力流体润滑的雷诺方程,把它应用于有限长径向滑动轴承的求解。通过数值计算得到了偶应力参数对有限长径向轴承的承载力、流量系数和摩擦系数的影响。     

LARGE-EDDY AND DETACHED-EDDY SIMULATIONS OF THE SEPARATED FLOW AROUND A CIRCULAR CYLINDER

The separated turbulent flow around a circular cylinder is investigated using Large-Eddy Simulation (LES), Detached-Eddy Simulation (DES, or hybrid RANS/LES methods), and Unsteady Reynolds-Averaged Navier-Stokes (URANS). The purpose of this study is to examine some typical simulation approaches for the prediction of complex separated turbulent flow and to clarify the capability of applying these approaches to a typical case of the separated turbulent flow around a circular cylinder. Several turbulence models, i.e. dynamic Sub-grid Scale (SGS) model in LES, the DES-based Spalart-Allmaras (S-A) and k ? ω Shear-Stress-Transport (SST) models in DES, and the S-A and SST models in URANS, are used in the calculations. Some typical results, e.g., the mean pressure and drag coefficients, velocity profiles, Strouhal number, and Reynolds stresses, are obtained and compared with previous computational and experimental data. Based on our extensive calculations, we assess the capability and performance of these simulation approaches coupled with the relevant turbulence models to predict the separated turbulent flow.     

三维圆柱绕流数值模拟湍流方法的选择

研究湍流模拟方法对三维圆柱绕流数值模拟精度的影响,分别采用雷诺平均法（RANS）中的κ-ω模型、SST模型以及大涡模拟法（LES）对亚临界区内雷诺数Re=3 900时的三维圆柱绕流进行数值计算,分析了圆柱体表面的受力、圆柱后流场时均速度特性与瞬时涡量分布情况。结果表明,当流体流过圆柱表面时,圆柱表面出现的与流速方向相反的负压力差区域使流体从圆柱表面分离,引起了不稳定的周期性交替脱落的湍流涡泄,从而在圆柱表面产生周期性波动的升力,同时在圆柱后近流场区域形成回流区。研究还发现,LES法对圆柱体的受力以及流场时均速度特性的模拟效果要优于κ-ω模型与SST模型;相较于前人利用浸入边界法得到的模拟结果,LES法的模拟精度也有了较大提升;同样,通过对瞬时流场涡量等值线图的分析,并与已有的模拟结果进行对比,发现LES法不但可以从整体上表现出漩涡的周期性脱落,而且对流场中不同位置的、复杂的小尺度湍流涡泄也描述得非常细致,得到的自由分离剪切层长度与湍流涡泄的卷曲度更符合湍流涡泄的特征。所以,在亚临界区,LES法对湍流的模拟效果相对较好。     

基于CFD的水泵水轮机推力轴承润滑性能流固耦合研究

水泵水轮机中推力轴承性能的变化直接影响其承载能力与机组运行稳定性,针对某水泵水轮机推力轴承,本文采用计算流体力学方法,对推力瓦的润滑特性、受力及变形情况进行了流固耦合分析,研究了最小油膜厚度及瓦面倾角对油膜承载力、推力瓦块等效应力及变形的影响。计算结果表明:推力瓦最大等效应力发生在出口处油膜厚度最小的位置,最大应力达到12 MPa,最大变形达到4.16μm;油膜承载力、瓦块等效应力及变形随油膜厚度的增加不断减小,随瓦面倾角的增加先增大后减小。     

NUMERICAL SOLUTION OF THE THREE-DIMENSIONAL ELASTOHYDRODYNAMIC LUBRICATION FOR HEAVILY-LOADED FINITE JOURNAL BEARINGS

A coupling of the finite element and the boundary element methods is applied to theanalysis of the three-dimensional elastohydrodynamic lubrication for heavily-loaded finite jour-nal bearings.An iterative scheme,which is used to overcome the difficulty of the convergence athigh eccentricity ratios,is provided in this paper.The scheme,which is called the weighted av-erage method here,is successfully carried out in the iterative procedures of a set of non-linear e-quations that is constituted by a two-dimensional Reynolds'equation,a viscosity-pressure equa-tion and three dimensional elasticity equations.The analysis yields the performance parametersand the minimum film thickness of finite journal bearings,which satisfy the elastohydrodynamicrequirements of realistic three-dimensional bearing geometries,under heavy loading.     

VIBRATION OF A SINGLE PROTEIN BUBBLE IN BINGHAM LIQUID

The vibration of a single protein bubble may take place under the action of high pressure difference. In this process, the bubble wall may experience a finite deformation. The equation describing the dynamics of the protein bubble with viscoelastic film in Bingham liquid is derived. A numerical solution to this equation is carried out to study the effect of liquid pressure, the characteristic parameters of Bingham liquid and the viscosity of the protein film on the finite deformation of the bubble. The results show that the vibration of the protein bubble wall is caused by the action of pressure difference, the elastic stress in finite deformation and the dissipation of viscosity of the protein film and Bingham liquid. The vibration is nonlinear. Decreasing the pressure difference between gas and Bingham liquid on both sides of the protein bubble will lead to a change of vibration performance. The frequency and amplitude are reduced, tegether with the speed of vibration damping. In addition, the deformation rate of the bubble is smaller when the amplitude of vibration is reduced, which means shorter time to reach a balance state. On the other side, the increase of the magnitude of viscosity of the protein film or the plastic viscosity of Bingham liquid can restrain the vibration of the protein bubble wall in the course of finite deformation, as a result, the load bearing capacity of bubble is enhanced.     

软弱岩体蠕变模型辨识与参数反演

压缩蠕变试验是了解岩体蠕变力学特性的重要手段。通过对大岗山水电站坝区软弱岩体现场压缩蠕变试验资料的分析,揭示坝区软弱岩体具有瞬时弹性变形、减速蠕变和弹性后效特性。通过对各种流变组合模型的辨识,确定采用广义开尔文模型来反映坝区软弱岩体的压缩蠕变特性。根据辨识的蠕变模型推导出了刚性承压板边缘岩体表面的压缩蠕变变形计算公式,据此采用优化反演法获得了坝区软弱岩体的瞬时弹性模量、黏弹性模量和黏滞系数等蠕变参数,从而为坝区边坡加固设计和稳定性分析提供了重要的岩体流变参数资料。     

水性胶乳固化剂对水泥基弹性灌浆料性能的影响

为了改善水泥基弹性灌浆材料在深水环境条件下的使用性能,研究了丙烯酸酯乳液和水性胶乳固化剂对水泥基弹性灌浆材料性能的影响,并对水泥基胶凝材料的配比进行优化。试验结果表明,在丙烯酸酯胶乳中加入水性胶乳固化剂并掺入灌浆料后,一部分丙烯酸酯与水性固化剂中的酰胺基在水泥水化形成的碱性条件下发生迈克尔加成反应和酰胺化反应生成聚丙烯酰胺系列化合物,提高了灌浆料水下不分散性,固结体水气强度比在90%以上;同时,水性胶乳固化剂促进了另一部分丙烯酸酯共聚胶乳固化成膜,弹性灌浆料与混凝土裂缝界面水下粘结抗折强度大于2.0 MPa,抗渗承载压强大于1.2 MPa。灌浆料中掺加适量橡胶细粉并优化配伍可有效降低固结体弹性模量,提高抗冲击韧性和弹性变形能力,灌浆料固结体体积稳定,无干缩开裂隐患。     

基于能量比系数的圆柱栅绕流LES方法研究

圆柱阵列流场不但是工程上常见的流动换热结构,而且绕流问题与湍流涡发展研究密切相关。该文采用数值模拟算法研究了不同雷诺数下的单列圆柱栅绕流的不可压缩流动。比较了非定常RANS方程计算得到的湍动能和耗散率,引入湍流能量比系数对初始计算网格进行重新划分和局部加密,进而建立适宜于大涡模拟网格尺度,其结果与PIV和RANS结果进行对比。结果表明,在湍流流场区域能量比系数达到30%-40%的情况下,就可得到工程实际需要的精确计算结果,这大大减少LES算法所需要的计算网格总数和时间。     

葛洲坝电厂水轮发电机组技术改造简述

葛注坝水电厂水轮发电机组存在着推力瓦烧损，大轴密封发卡，控制环抗磨块脱落，剪断锁易剪断等问题。针对其产生的原因采取了一些改进措施和进行了改造，收到了很好的效果。调速器更换为SJ－721A型电调DTJ－150／4－E1机械柜和WBST－A微机步进电机式调速器等，其主要技术性能达到国际先进水平。170MW机组的环形接力器由于刚度小变形大活塞漏油严重，改造中用4个摇摆接力器替代，确保了机组的稳定运行。水轮机叶片外缘加裙边后不仅振动减小，间隙空蚀减轻，在某些工况效率还有所提高。推力轴瓦更换为弹性金属塑料瓦，其承载能力大，摩擦系数小，安装工艺简单，改造是成功的，但仍存在着烧瓦的隐患。水轮机喷涂抗磨保护层收到一些效果，但中环和叶片强空蚀区的磨蚀尚无有效的解决办法。     

钢套筒混凝土压力管道(SSCP)外载超载试验研究

为了研究钢套筒混凝土压力管道(SSCP)的抗外压承载性能、管道内外层钢筒的变形特点以及管芯混凝土裂缝的开展规律,通过1/10尺寸普通SSCP模型外压破坏试验的方法,分析模型关键部位荷载—应变曲线、管顶荷载—位移曲线、外载管道破坏形式,得到外载试验中SSCP的一般破坏规律,即:初始裂缝分别出现于管顶和管底处;最终裂缝形态为侧向斜裂缝和自内向外的垂直裂缝;内钢筒屈曲破坏形成凹形。然后,基于等效刚度理论提出SSCP管道外压承载性能的弹性阶段承载力计算方法。计算结果表明:管道的弹性极限承载力为1 138 k N/m;管道的比例极限试验值在1 025~1 200 k N/m之间,与理论计算结果吻合较好,二者相对误差小于10%,证明了计算公式的准确性,满足工程需要;管道的塑性极限承载力试验值为2 176 k N/m。     

The effect of viscosity on the cavitation characteristics of high speed sleeve bearing

The effect of viscosity on the cavitation characteristics of a high speed sleeve bearing is investigated theoretically and experimentally. The cavitation characteristics, the cavitation shape and the cavitation location of a spiral oil wedge hydrodynamic bearing are investigated experimentally by using the transparent bearing and the high-speed camera. The generalized Reynolds equation is established with considerations of the cavitation mechanism based on the modified Elrod method in theory, and the cavitations of different viscosity sleeve bearings are analyzed and compared. It is shown that the cavitations are strip-shaped for both the high viscosity lubricant and the low viscosity lubricant, and in the rupture region of the oil film at a high speed, the oil vapour or bubbles are produced. With the decrease of the supply pressure and the increase of the rotating speed, the rupture area of the oil film increases distinctly. The cavitation area decreases distinctly and the quality of lubrication is better for the low viscosity lubricant than for the high viscosity lubricant. The experiment results in general are consistent with the theoretical results.