Comparative Study on Dynamic Characteristics of Double-Pad Inwardly and Outwardly Pumping Water-Lubricated Spiral-Groove Thrust Bearings

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Shaowen Zhang ◽  
Shuyun Jiang ◽  
Xiaohui Lin
Keyword(s):  
Comparative Study ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Control Volume ◽  
Operating Conditions ◽  
Axial Stiffness ◽  
Linear Perturbation ◽  
Spiral Groove ◽  
Reynolds Equations ◽  
Stiffness Coefficients

Abstract The dynamic characteristics of the double-pad inwardly pumping water-lubricated spiral-groove thrust bearing (SGTB) is different from that of the outwardly pumping version, especially under a high-speed condition. However, no literature on this topic can be found up to now. In this study, a comparative study on the dynamic characteristics of the two types of SGTBs is conducted. First, a turbulent lubrication model considering centrifugal and cavitating effects for the double-pad SGTB is developed based on gas–liquid two-phase flow. The steady-state and perturbed Reynolds equations of liquid phase are derived using linear perturbation method. Subsequently, the boundary fitted coordinate system and control volume method are applied to solve the Reynolds equations. Then, the axial stiffness coefficients of high-speed water-lubricated bearings are verified by an experimental study. Finally, the influence of operating conditions and configuration parameters on the dynamic behaviors for the two types of SGTBs is investigated. The results show that the double-pad outwardly pumping bearing is superior to the inwardly pumping version in all the dynamic coefficients when the radius ratio exceeds 0.65. When the tilt angle exceeds 1.2 × 10−4 as well as when the eccentricity ratio exceeds 0.7, the dynamic damping, angular and cross-coupled stiffness coefficients of the outwardly pumping bearing may be larger than those of the inwardly pumping one.

scholarly journals Dynamic Characteristics of High-speed Water-lubricated Spiral Groove Thrust Bearing based on Turbulent Cavitating Flow Lubrication Model

2020 ◽  
Author(s):  
Xiaohui Lin ◽  
shun Wang ◽  
shuyun Jiang ◽  
shaowen Zhang
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Cavitating Flow ◽  
Spiral Groove ◽  
Two Phase ◽  
Damping Coefficients ◽  
Stiffness Coefficients ◽  
Cavitation Effect ◽  
Experimental Apparatus ◽  
Rotary Speed

Abstract In this paper, a turbulent cavitating flow lubrication model based on two-phase fluid and population balance equation of bubbles was established to analyze dynamic characteristics of high speed water-lubricated spiral groove thrust bearings(SGTB). Stiffness and the damping coefficients of the SGTB were calculated using the perturbation pressure equations. An experimental apparatus was developed to verify the theoretical model. Simulating and experimental results show that the small-sized bubbles tend to generate in the turbulent cavitating flow when at a high rotary speed, and the bubbles mainly locate at the edges of the spiral groove. The simulating results also show that the direct stiffness coefficients are increased due to cavitation effect, and cross stiffness coefficients and damping coefficients are hardly affected by the cavitation effect. Turbulent effect on the dynamic characteristics of SGTB is much stronger than the cavitating effect.

Adiabatic Approximate Solution for Static and Dynamic Characteristics of Turbulent Partial Journal Bearings With Surface Roughness

1994 ◽  
Vol 116 (4) ◽  
pp. 672-680 ◽  
Author(s):  
H. Hashimoto ◽  
M. Mongkolwongrojn
Keyword(s):  
Surface Roughness ◽  
Approximate Solution ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Journal Bearings ◽  
Numerical Results ◽  
Operating Conditions ◽  
Finite Width ◽  
Homogeneous Surface ◽  
Static And Dynamic Characteristics

Hydrodynamic bearings are generally used for a long term, so the bearing surfaces may be roughened for many reasons such as wear, impulsive damage, foreign particles, cavitation erosion, rust, and so on. Under the turbulent operating conditions of high speed bearings, the surface roughness may result in considerable increase in both film pressure and temperature. This paper describes an adiabatic approximate solution for the static and dynamic characteristics of 180 deg partial journal bearings with homogeneous surface roughness. Applying the modified lubrication equation and energy equation, considering the combined effects of turbulence and surface roughness, to the finite width 180 deg partial journal bearings, the static and dynamic characteristics such as pressure and temperature distributions, Sommerfeld number, attitude angle, spring and damping coefficients and whirl onset velocity are obtained numerically. In the numerical analysis of the temperature distribution, adiabatic boundary conditions are assumed and then the heat transfer effect to the journal and bearing-bush surfaces is omitted. The numerical results are indicated in graphic form for various relative roughness under the mean Reynolds number of Re = 5000 and 10,000. Moreover, some numerical results of static characteristics are compared with the experimental results.

Finite Element Modal Analysis for Face-Milling Cutter

2013 ◽  
Vol 589-590 ◽  
pp. 19-22
Author(s):  
Lu Ning Liu ◽  
Zhen Yu Shi ◽  
Zhan Qiang Liu
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Face Milling ◽  
Operating Conditions ◽  
Mode Shapes ◽  
Milling Cutter ◽  
Characteristics Analysis ◽  
The Face

In this paper, a face-milling tool system is dealt with the Finite Element Modal Analysis (FEMA) using advanced contact technology functionalities. Dynamic characteristics analysis is performed and the stiffness contribution is included in the modal pre-stressed analysis. Natural frequencies and mode shapes of vibration are calculated. The FEMA is followed by experiments performed for different operating conditions of the face-milling system. The dynamic characteristics obtained in this paper can be used to optimize the face-milling cutter in high speed machining.

Effect of structural design parameters on nonlinear dynamic characteristics of the gear transmission

2021 ◽  
pp. 095440702110294
Author(s):  
Tiancheng Ouyang ◽  
Rui Yang ◽  
Yudong Shen ◽  
Jingxian Chen ◽  
Nan Chen
Keyword(s):  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
High Speed ◽  
Gear Tooth ◽  
Spur Gear ◽  
Operating Conditions ◽  
Design Parameters ◽  
Meshing Stiffness ◽  
Nonlinear Dynamic Characteristics ◽  
Potential Energy Method

The calculation of time-varying meshing stiffness caused by the alternate contacting of the gear tooth is an essential prerequisite to obtain real and effective nonlinear dynamic characteristics of the transmission system, so that the significance of which cannot be overemphasized. Accordingly, this work proposes an improved method to get meshing stiffness with taking fillet-foundation and gear rim deflection into consideration. Compared to the traditional potential energy method, the proposed method has more superior accuracy and performance, and its effectiveness has been further verified by the finite element analytical model. After that, an ideal eight degree of freedoms (DOFs) dynamic model of one stage mass-spring-damper involute spur gear, including lateral and torsional motions, is established to study the dynamic characteristics. Due to the complexity of the gear system operating conditions, we also investigate the influence of various parameters including hub bore radius, transmitting load, and rotation speed on dynamic features, especially in heavy-load and high-speed conditions. From the results, it can be concluded that these parameters will play a prominent role in the spur gear pair dynamic behaviors, providing a certain guidance for gear design.

scholarly journals ANALYSIS OF THE IMPACT OF SPECIAL CONSTRUCTIONS OF GAP SEALS ON THE DYNAMICS OF CENTRIFUGAL MACHINES

ScienceRise ◽  
2020 ◽  
pp. 3-13
Author(s):  
Serhii Shevchenko
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Dynamic Properties ◽  
Dynamic Performance ◽  
Operating Conditions ◽  
Centrifugal Pumps ◽  
Labyrinth Seals ◽  
Research Results ◽  
The Impact ◽  
Technological Product

The object of research: the influence of the design features of special gap seals on the dynamic characteristics of centrifugal machines. Investigated problem: harmonization of the consumption and dynamic characteristics of the seals of the rotors of high-speed machines by applying special design methods. Main scientific results: The mechanism and operating conditions of seals with floating rings are described. It is determined that the most effective from the point of view of dynamic characteristics is the variant of the semi-movable ring. Expressions for determining the conditions of angular and radial immobility of a floating ring are obtained. The design options for deformable gap seals, including deformable floating rings, deformable interwheel seals and seals with an axially movable deformable sleeve, have been investigated. The scope of their application for unique machines with high requirements for tightness and vibration reliability has been determined. Variants of the design of labyrinth seals have been investigated. The analysis shows that the dynamic properties of labyrinth seals significantly depend on the relative position of the ridges. Overlapping ridged seals have the worst dynamic performance of the labyrinth seal designs. The honeycomb seal has more favorable dynamic properties, and the well seal has the best combination of consumption and dynamic characteristics. The dynamic characteristics are especially important for the seals of high-speed rotors of centrifugal machines. The area of practical use of the research results: Enterprises that manufacture centrifugal machines: pumps and compressors. Innovative technological product: a methodology for the selection, design and calculation of special designs of gap seals with optimization of dynamic and flow characteristics. Scope of application of the innovative technological product: The obtained research results will be useful in the design and manufacture of centrifugal pumps and compressors for any parameters.

Static and dynamic characteristics and stability analysis of high-speed water-lubricated hydrodynamic journal bearings

2021 ◽  
pp. 135065012110270
Author(s):  
Bo Xu ◽  
Hun Guo ◽  
Xiaofeng Wu ◽  
Yafeng He ◽  
Xiangzhi Wang ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Load Capacity ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Inertia Effect ◽  
Static And Dynamic Characteristics ◽  
Damping Coefficients ◽  
Stiffness And Damping

The purpose of this paper is to analyze the influence of turbulent, inertia, and misaligned effects on the static and dynamic characteristics and stability of high-speed water-lubricated hydrodynamic journal bearings. Based on the Navier–Stokes equation, the mixing-length theory, and the essential assumption that the velocity profile is not strongly affected by inertia force, the fluid lubrication model with turbulent, inertia, and misaligned effects is established, and then the stability analysis of bearings is carried out based on the equation of motion with four degrees of freedom. The model is solved by the finite difference method and the numerical results are compared under different operating conditions. The results show that the turbulent effect greatly increases the load capacity, power consumption, stiffness and damping coefficients, and stability of bearings, and the inertia effect significantly increases the volume flow rate of bearings, and the misaligned effect increases the load capacity, stiffness and damping coefficients, and stability of bearings. In high rotary speed and moderate eccentricity ratios, the influence of the inertia effect on the load capacity, stiffness coefficients, and stability cannot be neglected.

scholarly journals Theoretical Solutions for Dynamic Characteristics of Liquid Annular Seals with Herringbone Grooves on the Stator Based on Bulk-Flow Theory

2018 ◽  
Vol 2018 ◽  
pp. 1-13
Author(s):  
Lulu Zhai ◽  
Zhonghuang Chi ◽  
Jia Guo ◽  
Zhenjie Zhang ◽  
Zuchao Zhu
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Flow Theory ◽  
Operating Conditions ◽  
Bulk Flow ◽  
Analysis Method ◽  
The Stability ◽  
Herringbone Grooves ◽  
Better Than ◽  
Annular Seals

Liquid annular seals are primarily used to control the leakage in high-speed turbomachinery, especially in nuclear and petrochemical pumps. In this paper, a theoretical analysis method for dynamic characteristics of liquid seals with herringbone grooves on the stator is proposed based on bulk-flow theory. Steady-state velocities and leakage rates within the upstream and downstream spiral parts and the middle plain part taking account of the pumping effects are figured out first with the inertia term of the fluid within the whole seal. Then, the dynamic characteristics of the whole seal are solved based on Childs’ finite-length solutions and verified by comparing with experimental hydraulic forces. Moreover, characteristic coefficients and instability parameters of the herringbone-grooved teeth-on-stator (TOS) seals and teeth-on-rotor (TOR) seals of the same size under different pressure differences are predicted and compared in detail. The influences of the lengths of constituent parts on the dynamic characteristics and instability parameters of the model seals are theoretically investigated. The results show that the stability of the TOS seal is much better than that of the TOR seal under most operating conditions. And the lengths of the middle plain part significantly affect the dynamic characteristics and the stability parameter.

Analysis of static and dynamic characteristics of spiral-grooved gas journal bearings in high speed

2019 ◽  
Vol 233 (19-20) ◽  
pp. 6774-6792 ◽  
Author(s):  
Laiyun Song ◽  
Kai Cheng ◽  
Hui Ding ◽  
Shijin Chen ◽  
Qiang Gao
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Load Capacity ◽  
Structural Parameters ◽  
Dynamic Stiffness ◽  
Journal Bearings ◽  
Linear Perturbation ◽  
Static And Dynamic Characteristics ◽  
Gas Bearings ◽  
Spiral Grooves

The spiral grooves structures could promote load capacity and improve stability of the gas journal bearings working in high-speed condition. In this study, the unsteady Reynolds equation is solved by linear perturbation method and finite difference method in which the mesh of the groove region is specially treated. The static and dynamic characteristics of spiral grooves journal gas bearings are investigated in different working conditions and the pumping effect caused by spiral-groove structure is revealed and analyzed. Further, the influences of groove structural parameters on the dynamic stiffness and damping coefficients are studied and discussed, which provides guidelines for the design of the journal gas bearings with spiral grooves.

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