Comparison Between Plain and Herringbone-Grooved Aerodynamic Journal Bearings

2007 ◽  
Author(s):  
Guido M. J. Delhaes ◽  
Anton van Beek ◽  
Ron A. J. van Ostayen ◽  
Rob H. Munnig-Schmidt
Keyword(s):  
Rotational Speed ◽  
High Speed ◽  
Load Capacity ◽  
Journal Bearings ◽  
Plain Bearing ◽  
Attitude Angle

Aerodynamic journal bearings are commonly used to support high-speed rotors. In applications where the shaft rotates concentric, like turbines and high-speed spindles, grooved aerodynamic bearings are used because they can run concentric. Plain aerodynamic journal bearings are unstable in the concentric position and are therefore not used for these applications. The instability is caused by the 90° attitude angle of the plain bearing at low rotational speeds. However by increasing the rotational speed the attitude angle of the plain bearing approaches the attitude angle of the grooved bearing. Moreover up to a certain speed the load capacity of the plain bearing is higher than the load capacity found for grooved bearings. In certain circumstances plain bearings might be preferable, since the plain bearing is much easier to manufacture. In this work a comparison is outlined for the plain and herringbone grooved bearings.

Design of Multi-Recess Hydrostatic Journal Bearings for Minimum Total Power Loss

1974 ◽  
Vol 96 (1) ◽  
pp. 226-232 ◽  
Author(s):  
C. Cusano ◽  
T. F. Conry
Keyword(s):  
Rotational Speed ◽  
Power Loss ◽  
Load Capacity ◽  
Maximum Load ◽  
Journal Bearings ◽  
Design Criterion ◽  
Total Power ◽  
Eccentricity Ratio ◽  
Constant Ratio ◽  
Design Charts

The design problem is formulated for multi-recess hydrostatic journal bearings with a design criterion of minimum total power loss. The design is subject to the constraints of constant ratio of the recess area to the total bearing area and maximum load capacity for a given recess geometry. The L/D ratio, eccentricity ratio, ratio of recess area to total bearing area, and shaft rotational speed are considered as parameters. The analysis is based on the bearing model of Raimondi and Boyd [1]. This model is generally valid for low-to-moderate speeds and a ratio of recess area-to-total bearing area of approximately 0.5 or greater. Design charts are presented for bearings having a ratio of recess area-to-total bearing area of 0.6 and employing capillary and orifice restrictors, these being the most common types of compensating elements. A design example is given to illustrate the use of the design charts.

scholarly journals Mathematical Model and Analysis of the Water-Lubricated Hydrostatic Journal Bearings considering the Translational and Tilting Motions

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Hui-Hui Feng ◽  
Chun-Dong Xu ◽  
Jie Wan
Keyword(s):  
High Speed ◽  
Reynolds Equation ◽  
Load Capacity ◽  
Journal Bearings ◽  
Linear Perturbation ◽  
Eccentricity Ratio ◽  
Dynamic Coefficients ◽  
Pressure Fields ◽  
Dynamic Performances ◽  
Rotary Speed

The water-lubricated bearings have been paid attention for their advantages to reduce the power loss and temperature rise and increase load capacity at high speed. To fully study the complete dynamic coefficients of two water-lubricated, hydrostatic journal bearings used to support a rigid rotor, a four-degree-of-freedom model considering the translational and tilting motion is presented. The effects of tilting ratio, rotary speed, and eccentricity ratio on the static and dynamic performances of the bearings are investigated. The bulk turbulent Reynolds equation is adopted. The finite difference method and a linear perturbation method are used to calculate the zeroth- and first-order pressure fields to obtain the static and dynamic coefficients. The results suggest that when the tilting ratio is smaller than 0.4 or the eccentricity ratio is smaller than 0.1, the static and dynamic characteristics are relatively insensitive to the tilting and eccentricity ratios; however, for larger tilting or eccentricity ratios, the tilting and eccentric effects should be fully considered. Meanwhile, the rotary speed significantly affects the performance of the hydrostatic, water-lubricated bearings.

Static Performance Analysis of Foil Thrust Bearing Based on Thin Plate Theory

2014 ◽  
Vol 621 ◽  
pp. 437-442
Author(s):  
Jian Jun Zhu ◽  
Jian Jun Du ◽  
Bing Li ◽  
Chang Lin Li ◽  
Dun Liu
Keyword(s):  
Thin Plate ◽  
Rotational Speed ◽  
High Speed ◽  
Plate Theory ◽  
Load Capacity ◽  
Structural Parameters ◽  
Structural Deformation ◽  
Foil Thickness ◽  
Frictional Torque ◽  
Eccentricity Ratio

The thrust foil bearing, as one of the key parts in high-speed rotating machineries, is used to sustain the axial force, and its load performance has a crucial relationship with the structural parameters and working condition. In this paper the top foil is modeled as a thin plate supported by the bumps underneath. The finite element method (FEM) is used to calculate the structural deformation coupled with the pressure distribution obtained through the solution of Reynolds equation by the finite difference method (FDM). The effects of structural and operating parameters, such as rotational speed, eccentricity ratio, top foil thickness and bump foil thickness on the load capacity and frictional torque are discussed in detail. The results show that the increase of rotational speed, eccentricity ratio and bump foil thickness is beneficial to increase the load capacity and frictional torque. The effect of variation of top foil thickness on load capacity is not obvious, which implies that the top foil plays a role in building the lubricant surface rather than providing supporting stiffness.

Rotordynamic and Bearing Upgrade of a High-Speed Turbocharger

2002 ◽  
Vol 125 (1) ◽  
pp. 95-101 ◽  
Author(s):  
B. C. Pettinato ◽  
P. DeChoudhury
Keyword(s):  
High Speed ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Journal Bearings ◽  
Experimental Results ◽  
Thrust Bearings ◽  
Vibration Data ◽  
Oil Leakage ◽  
Bearing Life ◽  
Thrust Load

The paper discusses the redesign of a high-speed turbocharger for improved bearing life and mechanical operation. The bearings were changed from a pair of combination journal/thrust bearings to a pair of redesigned journal bearings with double acting thrust bearing at the center of the unit. Internal oil passages, drain cavities, and seals were also revised. These modifications resulted in reduced oil leakage across end seals, reduced coke buildup at the turbine, increased thrust load capacity, and improved rotordynamics. Both the analytical and experimental results, which consisted of bearing performance and vibration data of original and modified systems are presented.

Modal and Nodal EHD Analysis for Gas Journal Bearings

2004 ◽  
Author(s):  
S. Boedo ◽  
J. F. Booker
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Slip Flow ◽  
Computational Cost ◽  
Elastohydrodynamic Lubrication ◽  
Journal Bearings ◽  
Boundary Effects ◽  
Mode Shapes ◽  
State Variable ◽  
Judicious Choice

This paper presents a novel finite element elastohydrodynamic lubrication analysis appropriate for gas journal bearings under dynamic conditions. The method employs gas pressure as a state variable, and structural sleeve deformation is represented by a linear combination of pre-selected mode shapes obtained from a related eigenvalue problem. The method takes into account temporal variation of journal position and velocity, and second-order slip flow boundary effects are included at no additional computational cost. The formulation is subsequently applied to a particular example (flexible large-aspect ratio, high-speed, MEMS-scale journal microbearing), where it is shown that a judicious choice of structural sleeve elasticity can significantly improve bearing performance (as measured by pressure distribution and load capacity) when compared with results obtained using rigid bearing surfaces.

Computational design and analysis of aerostatic journal bearings with application to ultra-high speed spindles

2016 ◽  
Vol 231 (7) ◽  
pp. 1205-1220 ◽  
Author(s):  
Siyu Gao ◽  
Kai Cheng ◽  
Shijin Chen ◽  
Hui Ding ◽  
Hongya Fu
Keyword(s):  
High Speed ◽  
Volume Flow Rate ◽  
Load Capacity ◽  
Computational Design ◽  
Design Guidelines ◽  
Journal Bearings ◽  
Weighted Residual Method ◽  
Precision Engineering ◽  
Pressure Distributions ◽  
Ultra High Speed

Aerostatic bearings are the critical parts of ultra-high speed spindles applied to precision milling, grinding, and other precision engineering applications. In this paper, the computational design and analysis of aerostatic journal bearings at ultra-high speed spindles are investigated particularly in light of the nonlinear compressible Reynolds equation and the associated computational analysis and algorithms using the finite element method-based Galerkin weighted residual method. The steady-state static and dynamic behaviors of aerostatic journal bearings are systematically studied, including pressure distributions, load capacity, stiffness, attitude angle, and volume flow rate under conditions of various operating speeds and eccentricity ratios. The coupling of the aerostatic and aerodynamic effects within ultra-high speed aerostatic journal bearings is further explored. The obtained results are formulated as design guidelines for aerostatic journal bearings applied to air-bearing spindles operating in high precision and ultra-high rotational speeds.

Rotordynamic and Bearing Upgrade of a High-Speed Turbocharger

2001 ◽  
Author(s):  
Brian C. Pettinato ◽  
Pranabesh DeChoudhury
Keyword(s):  
High Speed ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Flow Distribution ◽  
Journal Bearings ◽  
Original Design ◽  
Thrust Bearings ◽  
Vibration Data ◽  
Bearing Life ◽  
Oil Flow

The paper discusses the redesign of a high-speed turbocharger for improved bearing life and mechanical operation. The modifications resulted in reduced oil leakage across the end seal, reduced coke buildup at the turbine, increased thrust load capacity, and improved rotordynamics. In particular, rotordynamic stability was improved by eliminating subsynchronous vibration at the operating speed. The redesign consisted of changing the bearings from a pair of combination journal/thrust bearings to a pair of journal bearings and a double acting thrust bearing at the center of the unit. The active thrust bearing was moved away from the hot turbine end of the machine. The thrust bearing geometry was modified for increased minimum film thickness, reduced metal temperature, and increased load capacity. Inlet and drain passages were revised for better oil flow distribution. Unit rotordynamics were improved by upgrading the journal bearings from three-axial-groove to three-lobe design. The upgraded unit kept the same footprint as the original design with only piping modifications required. Extensive analysis and testing were conducted. Testing of the original and revised turbochargers showed improvements in the redesign with reduced bearing metal temperatures and improved rotordynamic stability. Theoretical results along with test data consisting of bearing performance and vibration data of the original and modified system are presented in this paper.

The Application of Double Conical Journal Bearings in High Speed Centrifugal Pumps — Parts 1 and 2

1975 ◽  
Vol 189 (1) ◽  
pp. 221-230 ◽  
Author(s):  
C. Ettles ◽  
O. Svoboda
Keyword(s):  
Axial Load ◽  
High Speed ◽  
Load Capacity ◽  
Correct Choice ◽  
Journal Bearings ◽  
Radial Load ◽  
Centrifugal Pumps ◽  
Half Angle ◽  
Bearing Materials ◽  
Flow Compensation

Conical bearings can in principle support a combination of radial and axial load. Their application to centrifugal pumps is considered, which allows the thrust bearing of the conventional arrangement to be dispensed with. It is shown that with low pressure oil lubrication, the axial load of this type of bearing is limited to the ratio (axial load/radial load)=Tan A, where A is the half angle of the cone. Methods of avoiding this limitation are considered. The feasibility of water lubricated inclined journal bearings for centrifugal pumps is analysed. A ‘Vee’ configuration double conical journal bearing is considered with a central high pressure feed from the pump outlet. Although the enhancement of viscosity due to turbulence is not as great as anticipated, the bearing is shown to have an adequate axial and radial load capacity. It is shown that flow compensation or restriction to each side of the bearing is necessary to maintain the escaped flow at an acceptable level. The limits of bearing operation are set by acceptable film thickness rather than excessive temperature rise. For this reason, the correct choice of bearing materials to run under thin film or no film conditions in the presence of dirt is probably more important than correct hydrodynamic design.

Rarefaction Effect on the Characteristics of Micro Gas Journal Bearings

2009 ◽  
Author(s):  
Haijun Zhang ◽  
Qin Yang
Keyword(s):  
Knudsen Number ◽  
Reynolds Equation ◽  
Load Capacity ◽  
Slip Boundary Condition ◽  
Journal Bearings ◽  
Radial Clearance ◽  
Clearance Ratio ◽  
Attitude Angle ◽  
Modified Reynolds Equation ◽  
Bearing Number

Journal bearings, which are used to support radial loads in a rotating machine, have somewhat unusual requirements in MEMS deriving from the extremely shallow structures. Thus, the micro gas journal bearings are characterized by a very small length-diameter ratio, defined as the ratio of the bearing length to its diameter and a paradoxically large bearing clearance ratio, defined as the ratio of the average radial clearance to the bearing radius. Given the definition of the reference Knudsen number for micro gas journal bearings, the range of the reference Knudsen number is illustrated according to the viscosity values of air under different temperatures. With the reference Knudsen number being included, the modified Reynolds equation for micro gas journal bearings based on Burgdorfer’s first order slip boundary condition is put forward. The finite difference method (FDM) is employed to solve the modified Reynolds equation to obtain the pressure distribution, load capacities and attitude angles for micro gas journal bearings under different reference Knudsen numbers, bearing numbers and eccentricity ratios. Numerical analysis shows that the pressure profiles and non-dimensional load capacities decrease obviously with gas rarefaction strengthened, and the attitude angle changes conversely. Moreover, when the bearing number is smaller, the effect of gas rarefaction on the non-dimensional load capacity and attitude angle is less.

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.

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