The Effects of Temperature and Inertia on Hydrostatic Thrust Bearing Performance

1971 ◽  
Vol 93 (2) ◽  
pp. 307-312 ◽  
Author(s):  
L. L. Ting ◽  
J. E. Mayer
Keyword(s):  
Load Capacity ◽  
Operating Conditions ◽  
Performance Estimation ◽  
Rotational Inertia ◽  
Adiabatic Flow ◽  
Thrust Bearings ◽  
Adiabatic Theory ◽  
Bearing Life ◽  
Load Carrying ◽  
Effects Of Temperature

The effects of the lubricant rotational inertia and the temperature on the performance of parallel stepped hydrostatic thrust bearings have been investigated. Expressions for pressure and temperature distributions and load carrying capacities are obtained under adiabatic flow conditions. Satisfactory correlation between theory and experiment has been observed especially when the bearing speed is high. In order to insure the increase of load capacity as speed increases, the ratio of step location to bearing radius must be chosen no less than a limiting value which depends on the other geometry and operating conditions of the bearing. Since the bearing performance estimation by adiabatic theory is conservative, the design criteria provided will be practical and useful if long bearing life is essential.

CFD Thermohydrodynamic Analysis of 3-D Sector-Pad Thrust Bearings With Rectangular Dimples

2013 ◽  
Author(s):  
C. I. Papadopoulos ◽  
L. Kaiktsis ◽  
M. Fillon
Keyword(s):  
Carrying Capacity ◽  
Thermal Effects ◽  
Computational Study ◽  
Load Capacity ◽  
Operating Conditions ◽  
Load Carrying Capacity ◽  
Performance Indices ◽  
Thrust Bearings ◽  
Load Carrying ◽  
Texture Design

The paper presents a detailed computational study of flow patterns and performance indices in a dimpled parallel thrust bearing. The bearing consists of eight pads; the stator surface of each pad is partially textured with rectangular dimples, aiming at maximizing the load carrying capacity. The bearing tribological performance is characterized by means of Computational Fluid Dynamics (CFD) simulations, based on the numerical solution of the Navier-Stokes and energy equations for incompressible flow. Realistic boundary conditions are implemented. The effects of operating conditions and texture design are studied for the case of isothermal flow. First, for a reference texture pattern, the effects of varying operating conditions, in particular minimum film thickness (thrust load), rotational speed and feeding oil pressure are investigated. Next, the effects of varying texture geometry characteristics, in particular texture zone circumferential/radial extent, dimple depth and texture density on the bearing performance indices (load carrying capacity, friction torque and friction coefficient) are studied, for a representative operating point. For the reference texture design, the effects of varying operating conditions are further investigated, by also taking into account thermal effects. In particular, adiabatic conditions and conjugate heat transfer at the bearing pad are considered. The results of the present study indicate that parallel thrust bearings textured by proper rectangular dimples are characterized by substantial load carrying capacity levels. Thermal effects may significantly reduce load capacity, especially in the range of high speeds and high loads. Based on the present results, favorable texture designs can be assessed.

Computational Fluid Dynamics Thermohydrodynamic Analysis of Three-Dimensional Sector-Pad Thrust Bearings With Rectangular Dimples

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
C. I. Papadopoulos ◽  
L. Kaiktsis ◽  
M. Fillon
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Carrying Capacity ◽  
Thermal Effects ◽  
Operating Conditions ◽  
Load Carrying Capacity ◽  
Performance Indices ◽  
Thrust Bearings ◽  
Load Carrying ◽  
Texture Design

The paper presents a detailed computational study of flow patterns and performance indices in a dimpled parallel thrust bearing. The bearing consists of eight pads; the stator surface of each pad is partially textured with rectangular dimples, aiming at maximizing the load carrying capacity. The bearing tribological performance is characterized by means of computational fluid dynamics (CFD) simulations, based on the numerical solution of the Navier–Stokes and energy equations for incompressible flow. Realistic boundary conditions are implemented. The effects of operating conditions and texture design are studied for the case of isothermal flow. First, for a reference texture pattern, the effects of varying operating conditions, in particular minimum film thickness (thrust load), rotational speed and feeding oil pressure are investigated. Next, the effects of varying texture geometry characteristics, in particular texture zone circumferential/radial extent, dimple depth, and texture density on the bearing performance indices (load carrying capacity, friction torque, and friction coefficient) are studied, for a representative operating point. For the reference texture design, the effects of varying operating conditions are further investigated, by also taking into account thermal effects. In particular, adiabatic conditions and conjugate heat transfer at the bearing pad are considered. The results of the present study indicate that parallel thrust bearings textured by proper rectangular dimples are characterized by substantial load carrying capacity levels. Thermal effects may significantly reduce load capacity, especially in the range of high speeds and high loads. Based on the present results, favorable texture designs can be assessed.

An Accurate Solution of the Gas Lubricated, Flat Sector Thrust Bearing

1977 ◽  
Vol 99 (1) ◽  
pp. 82-88 ◽  
Author(s):  
I. Etsion ◽  
D. P. Fleming
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Thickness Distribution ◽  
Maximum Load ◽  
Accurate Solution ◽  
Operating Conditions ◽  
Thrust Bearings ◽  
Practical Design ◽  
Minimum Film Thickness

A flat sector shaped pad geometry for gas lubricated thrust bearings is analyzed considering both pitch and roll angles of the pad and the true film thickness distribution. Maximum load capacity is achieved when the pad is tilted so as to create a uniform minimum film thickness along the pad trailing edge. Performance characteristics for various geometries and operating conditions of gas thrust bearings are presented in the form of design curves. A comparison is made with the rectangular slider approximation. It is found that this approximation is unsafe for practical design, since it always overestimates load capacity.

Effects of double parabolic profiles with groove textures on the hydrodynamic lubrication performance of journal bearing under steady operating conditions

2020 ◽  
Vol 21 (3) ◽  
pp. 301
Author(s):  
Chongpei Liu ◽  
Wanyou Li ◽  
Xiqun Lu ◽  
Bin Zhao
Keyword(s):  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Operating Conditions ◽  
Lubricating Oil ◽  
Asperity Contact ◽  
Adiabatic Flow ◽  
Lubrication Performance ◽  
Load Carrying ◽  
Edge Wear ◽  
Journal Misalignment

The textures on the bushing surface have important effects on the performance of journal bearing. In this study, the effects of double parabolic profiles with groove textures on the hydrodynamic lubrication performance of journal bearing under steady operating conditions are investigated theoretically. The journal misalignment, asperity contact and thermal effects are considered, while the profile modifications due to running-in are neglected. The Winkler/Column model is used to calculate the elastic deformation of bushing surface and the adiabatic flow hypothesis is adopted to obtain the effective temperature of lubricating oil. The numerical solution is established by using finite difference and overrelaxation iterative methods, and the rupture zone of oil film is determined by Reynolds boundary conditions. The numerical results reveal that the double parabolic profiles with groove textures with proper location and geometric sizes can increase load carrying capacity and reduce friction loss under steady operating conditions, which effectively overcome the drawbacks of double parabolic profiles. This novel bushing profile may help to reduce the bushing edge wear and enhance the lubrication performance of journal bearing.

Analysis of Starved Thrust Bearings Including Temperature Effects

1987 ◽  
Vol 109 (3) ◽  
pp. 395-401 ◽  
Author(s):  
A. Artiles ◽  
H. Heshmat
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Operating Conditions ◽  
Geometrical Parameters ◽  
Two Dimensional ◽  
Thrust Bearings ◽  
Direct Iteration ◽  
Finite Thrust ◽  
Raphson Iteration

A method of analysis is described treating starvation in finite thrust bearing pads. A variable-size finite difference mesh is used to represent the two-dimensional temperature and pressure fields. A combination of Newton-Raphson iteration, direct iteration, and column matrix methods are used to solve for the start-of-film and minimum film thickness as well as the coupled two-dimensional energy and Reynolds equations. A parametric study describes the performance characteristics of the tapered land thrust bearing (flowrates, extent of fluid film, temperature rises, load capacity and torque) for different minimum film thicknesses and levels of starvation. This study considered variations in the geometrical parameters such as pad aspect ratio (L/R2=1/3, 1/2, 2/3) and extent of the pad (β=27, 42, and 57 deg) with an optimum taper ratio (β1/β=0.8). It is found that the effects of starvation are fairly small near the flooded condition but accelerate rapidly below the 50 percent starvation level. The start of the film (θ1) depends mostly on the level of starvation, and is essentially independent of the geometrical parameters, operating conditions or film thickness.

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.

Geometry Optimization of Textured Three-Dimensional Micro- Thrust Bearings

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
C. I. Papadopoulos ◽  
E. E. Efstathiou ◽  
P. G. Nikolakopoulos ◽  
L. Kaiktsis
Keyword(s):  
Carrying Capacity ◽  
Stokes Equations ◽  
Load Capacity ◽  
Three Dimensional ◽  
Load Carrying Capacity ◽  
Thrust Bearings ◽  
Micro Channels ◽  
Wide Range ◽  
Load Carrying ◽  
Bearing Load

This paper presents an optimization study of the geometry of three-dimensional micro-thrust bearings in a wide range of convergence ratios. The optimization goal is the maximization of the bearing load carrying capacity. The bearings are modeled as micro-channels, consisting of a smooth moving wall (rotor), and a stationary wall (stator) with partial periodic rectangular texturing. The flow field is calculated from the numerical solution of the Navier-Stokes equations for incompressible isothermal flow; processing of the results yields the bearing load capacity and friction coefficient. The geometry of the textured channel is defined parametrically for several width-to-length ratios. Optimal texturing geometries are obtained by utilizing an optimization tool based on genetic algorithms, which is coupled to the CFD code. Here, the design variables define the bearing geometry and convergence ratio. To minimize the computational cost, a multi-objective approach is proposed, consisting in the simultaneous maximization of the load carrying capacity and minimization of the bearing convergence ratio. The optimal solutions, identified based on the concept of Pareto dominance, are equivalent to those of single-objective optimization problems for different convergence ratio values. The present results demonstrate that the characteristics of the optimal texturing patterns depend strongly on both the convergence ratio and the width-to-length ratio. Further, the optimal load carrying capacity increases at increasing convergence ratio, up to an optimal value, identified by the optimization procedure. Finally, proper surface texturing provides substantial load carrying capacity even for parallel or slightly diverging bearings. Based on the present results, we propose simple formulas for the design of textured micro-thrust bearings.

scholarly journals EFFECT OF SURFACE ROUGHNESS ON STEADY PERFORMANCE OF HYDROSTATIC THRUST BEARINGS: RABINOWITSCH FLUID MODEL

2019 ◽  
Author(s):  
Udaya Pratap Singh
Keyword(s):  
Surface Roughness ◽  
Carrying Capacity ◽  
Load Capacity ◽  
Numerical Results ◽  
Integral Approach ◽  
Load Carrying Capacity ◽  
Film Pressure ◽  
Thrust Bearings ◽  
Longitudinal Roughness ◽  
Load Carrying

Purpose of the present theoretical investigation is to analyze the effects of surface roughness on the steady-state performance of stepped circular hydrostatic thrust bearings lubricated with non-Newtonian Rabinowitsch type fluids. Results for film pressure and load-carrying capacity have been plotted and analyzed on the basis of numerical results. To take the effects of surface roughness into account, Christensen theory of rough surface has been adopted. The expression for pressure gradient has been derived by means of the energy integral approach. This approach avoids the derivation of Reynolds’ equation. The numerical results for film pressure and load capacity have been obtained using Mathematica. It was observed that in comparison with smooth surfaces, dimensionless film pressure and load capacity is lower for longitudinal roughness and higher for circular roughness patterns with and the variations are significant. Load carrying capacity decreases with the increase of longitudinal roughness and, increases with the increase of circular roughness. Further, the effects of surface roughness and non-Newtonian lubricants are significant for larger values of inertia parameter. Because of the closeness of results to the experimental values, this study will be helpful in the design of circular hydrostatic thrust bearings.

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.

Effect of Operating Conditions on the Elastohydrodynamic Performance of Foil Thrust Bearings for Supercritical CO2 Cycles

2016 ◽  
Vol 139 (4) ◽  
Author(s):  
Kan Qin ◽  
Ingo H. Jahn ◽  
Peter A. Jacobs
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Supercritical Co2 ◽  
Load Capacity ◽  
Fluid Phase ◽  
Operating Conditions ◽  
Inertia Force ◽  
Fluid Structure ◽  
Thrust Bearings ◽  
Foil Bearings

In this paper, a quasi-three-dimensional fluid–structure model using computational fluid dynamics for the fluid phase is presented to study the elastohydrodynamic performance of foil thrust bearings for supercritical CO2 cycles. For the simulation of the gas flows within the thin gap, the computational fluid dynamics solver Eilmer is extended, and a new solver is developed to simulate the bump and top foil within foil thrust bearings. These two solvers are linked using a coupling algorithm that maps pressure and deflection at the fluid structure interface. Results are presented for ambient CO2 conditions varying between 0.1 and 4.0 MPa and 300 and 400 K. It is found that the centrifugal inertia force can play a significant impact on the performance of foil thrust bearings with the highly dense CO2 and that the centrifugal inertia forces create unusual radial velocity profiles. In the ramp region of the foil thrust bearings, they generate an additional inflow close to the rotor inner edge, resulting in a higher peak pressure. Contrary to the flat region, the inertia force creates a rapid mass loss through the bearing outer edge, which reduces pressure in this region. This different flow fields alter bearing performance compared to conventional air foil bearings. In addition, the effect of turbulence in load capacity and torque is investigated. This study provides new insight into the flow physics within foil bearings operating with dense gases and for the selection of optimal operating condition to suit CO2 foil bearings.

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