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.

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.

Numerical Study of Single Pad Externally Adjustable 120° Pad Bearing Using Fluid Structure Interaction

2021 ◽  
Author(s):  
Harishkumar Kamat ◽  
Chandrakant R. Kini ◽  
Satish B. Shenoy
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Fluid Film ◽  
Structural Deformation ◽  
Radial Clearance ◽  
Solution Technique ◽  
Eccentricity Ratio ◽  
Positive Direction ◽  
Film Pressure ◽  
Marine Propulsion

Abstract High-speed turbomachinery like turbine generators and marine propulsion systems uses special fluid film bearing called externally adjustable pad bearing due to their great advantages. The principal feature of this bearing is to alter the radial clearance and film thickness along the circumferential direction to improve the bearing performance parameters. In the present study, the effect of radial and tilt adjustment of 120° pad both in upward (or negative) and downward (or positive) direction on the bearing performance is predicted for various eccentricity ratios using the CFD technique. Later the influence of fluid film pressure on the bearing pad is examined using the FSI technique. Furthermore, the effect of eccentricity ratio on the bearing performance and also on pad structure is also analyzed using CFD coupled FSI analysis. The solution technique of the present numerical analysis is validated with the already published literature and the results are in good agreement. The numerical results suggest that for bearing with negative radial and negative tilt adjustment, bearing performance is superior compared to the other adjustments. However, the structural deformation is also significant for the negative radial and negative tilt adjustment. It is also observed that pad deformation increases with the increase in eccentricity ratio as there has been a rise in fluid film pressure.

scholarly journals Sand Removal Mechanism of a High-Speed Roller Bit with Helical Sealing

2019 ◽  
Vol 9 (18) ◽  
pp. 3830
Author(s):  
Yi Zhou ◽  
Bin Tan ◽  
Yuxing Huang
Keyword(s):  
Rotational Speed ◽  
High Speed ◽  
Oil And Gas ◽  
Structural Parameters ◽  
Working Life ◽  
Removal Mechanism ◽  
Drilling Tool ◽  
Rock Stratum ◽  
Factors Affecting ◽  
Simulation And Experiment

A roller bit is a drilling tool widely used in oil and gas exploitation. The roller bit is applied to cutting the rock stratum, and its working life and rotational speed are important factors affecting the drilling efficiency. Moreover, a bearing sealing affects the working life and rotational speed of a bit. This paper proposes a helical sealing structure that addresses the problems of severe sealing wear and a short working life. This structure has been used in many engineering fields but was first applied to the roller bit. This paper investigates the sand removal mechanism of helical sealing through simulation and experiment. Additionally, helical sealing parameters were optimized. The optimum structural parameters of helical sealing in a high-speed roller bit were obtained. It was shown that the helical sealing structure can be applied to a roller bit with good effects of sealing and sand removal.

Experimental study on frictional loss of high-speed bearings based on free-deceleration and energy-balance methods

2019 ◽  
Vol 71 (4) ◽  
pp. 509-514 ◽  
Author(s):  
Shengli Tian ◽  
Xiaoan Chen ◽  
Tianchi Chen ◽  
Ye He
Keyword(s):  
Energy Balance ◽  
Rotational Speed ◽  
High Speed ◽  
Mechanical Systems ◽  
Coupling Factor ◽  
Thermomechanical Coupling ◽  
Frictional Torque ◽  
Frictional Loss ◽  
Content Type ◽  
Relationship Of

Purpose The purpose of this study is to investigate accurate and effective experimental methods for measuring the frictional loss of bearings (FLB) in mechanical systems and to measure the effect of various operating parameters on the frictional loss of high-speed mechanical systems. Design/methodology/approach Two novel methods were studied in this paper to measure the FLB: the free-deceleration method and the energy-balance method. A special high-speed motorised spindle and a friction loss test rig were designed and built to measure the effects of rotational speed, lubrication, preload and operating temperature on the FLB. Findings The experimental results showed that the frictional torque of bearings increases initially but then decreases with an increase in rotational speed. Similarly, the FLB decreases initially and then increases with an increase in temperature because of the influence of the viscosity–temperature relationship of the lubricant and the thermomechanical coupling factor. The optimal lubricant flow was determined, and the effectiveness of a novel preload online adjusting device was verified through experiments. Originality/value The research results of this paper provide the basis and methods for the measurement, reduction and prediction of the FLB in mechanical systems.

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.

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.

Limits for High-Speed Operation of Gas Foil Bearings

2006 ◽  
Vol 128 (3) ◽  
pp. 670-673 ◽  
Author(s):  
Tae Ho Kim ◽  
Luis San Andrés
Keyword(s):  
High Speed ◽  
Ultimate Load ◽  
Load Capacity ◽  
Structural Deformation ◽  
Accurate Estimation ◽  
Algebraic Equations ◽  
Ultimate Load Capacity ◽  
Foil Bearings ◽  
Reliable Performance ◽  
Initial Assembly

Commercial oil-free microturbomachinery implements gas foil bearings (GFBs) for reliable performance with improved efficiency. However, GFB modeling is still largely empirical, lacking experimental validation. An analysis of simple GFBs operating at large shaft speeds (infinite speed number) follows. The bearing ultimate load and stiffness coefficients are derived from simple algebraic equations for the gas film pressures at the equilibrium journal position and due to small amplitude journal motions, respectively. GFBs without a clearance or with assembly interference are easily modeled. The underlying elastic structure (bump foil strip) determines the ultimate load capacity of a GFB as well as its stiffnesses, along with the limiting journal displacement and structural deformation. Thus, an accurate estimation of the actual minimum film thickness is found prior to performing calculations with a complex computational model, even for the case of large loads that result in a journal eccentricity well exceeding the nominal clearance, if applicable. An initial assembly preload (interference between shaft and foil) increases the GFB static stiffness at both null and infinite rotor speeds. At infinite speed, cross-coupled stiffnesses are nil, and thus, GFBs are impervious to hydrodynamic whirl instability.

Gas Foil Bearings: Limits for High-Speed Operation

2005 ◽  
Author(s):  
Luis San Andre´s ◽  
Tae Ho Kim
Keyword(s):  
High Speed ◽  
Ultimate Load ◽  
Load Capacity ◽  
Structural Deformation ◽  
Accurate Estimation ◽  
Algebraic Equations ◽  
Ultimate Load Capacity ◽  
Foil Bearings ◽  
Reliable Performance ◽  
Initial Assembly

Commercial oil-free micro turbomachinery relies on gas foil bearings (GFBs) for reliable performance with improved efficiency. However, GFB modeling is still largely empirical, lacking experimental validation. An analysis of simple GFBs operating at large shaft speeds (infinite speed number) follows. The bearing ultimate load and stiffness coefficients are derived from simple algebraic equations for the gas film pressures at the equilibrium journal position and due to small amplitude journal motions, respectively. GFBs without a clearance or with assembly interference are easily modeled. The underlying elastic structure (bump foil strip) determines the ultimate load capacity of a GFB as well as its stiffnesses, along with the limiting journal displacement and structural deformation. Thus, an accurate estimation of the actual minimum film thickness is found prior to performing calculations with a complex computational model, even for the case of large loads that result in a journal eccentricity well exceeding the nominal clearance, if applicable. An initial assembly preload (interference between shaft and foil) increases the GFB static stiffness at both null and infinite rotor speeds. At infinite speed, cross-coupled stiffnesses are nil; and thus, GFBs are impervious to hydrodynamic whirl instability.

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.

The Steady-State Characteristics of a Hydrostatic Thrust Bearing With a Floating Disk

1989 ◽  
Vol 111 (2) ◽  
pp. 352-357
Author(s):  
M. Harada ◽  
J. Tsukazaki
Keyword(s):  
Steady State ◽  
Rotational Speed ◽  
Power Loss ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Frictional Torque ◽  
Thrust Bearings ◽  
Stable Position ◽  
Surface Configuration

To reduce the frictional power loss of hydrostatic thrust bearings, the hydrostatic thrust bearing with a floating disk shaped in a simplified configuration is proposed. And the load capacity and the frictional torque are experimentally investigated in laminar and superlaminar regimes. Following results can be obtained: (1) The disk floats at a certain stable position for given shaft rotational speed and rotates at nearly half rotational speed of the shaft. (2) The frictional torque of this type of the bearing is less than half of a conventional hydrostatic thrust bearing with the same surface configuration as the floating disk.

Sign in / Sign up

Export Citation Format

Share Document