Design of Efficient Turbulent Thrust Bearings III. Self-Pressurized Design

1981 ◽  
Vol 103 (3) ◽  
pp. 459-466
Author(s):  
D. F. Wilcock
Keyword(s):  
Temperature Rise ◽  
Power Loss ◽  
Power Efficiency ◽  
High Speed ◽  
Hybrid Design ◽  
Thrust Bearings ◽  
Higher Power ◽  
Hydrostatic Load ◽  
Oil Flow ◽  
Higher Temperature

Turbulence makes high speed conventionally designed bearings operate with higher power loss, higher temperature rise, and lower oil flow than would be predicted from conventional laminar analysis. The objective of this paper is to present a new concept for increasing the load/power efficiency of large thrust bearings by a hybrid design employing hydrostatic load support combined with hydrodynamic pads. Self-pressurization using a shaft-center feed to radial ducts in the runner provides reliability fully equal to conventional bearing-fed designs.

Design of Efficient Turbulent Thrust Bearings

1977 ◽  
Vol 99 (1) ◽  
pp. 113-121
Author(s):  
D. F. Wilcock
Keyword(s):  
High Temperature ◽  
Film Thickness ◽  
Temperature Rise ◽  
Power Loss ◽  
High Speed ◽  
Thrust Bearings ◽  
Higher Power ◽  
Minimum Film Thickness ◽  
Oil Flow ◽  
High Temperature Rise

Turbulence makes high speed conventionally designed bearings operate with higher power loss, high temperature rise, and lower oil flow than predicted. The objective of this paper is to show that the phenomenon of turbulence can be turned to the designer’s and operator’s advantage; and that turbulent thrust bearings can be designed to operate with lower power loss than conventional design would predict, while maintaining the same minimum film thickness and safe temperature rise.

Thermal Analysis and Test for a High Speed PM Machine for Fan Application

2011 ◽  
Vol 383-390 ◽  
pp. 4727-4734 ◽  
Author(s):  
Ji Qiang Wang ◽  
Feng Xiang Wang
Keyword(s):  
Thermal Analysis ◽  
Temperature Rise ◽  
Power Loss ◽  
High Speed ◽  
Heat Dissipation ◽  
Machine Design ◽  
Test Results ◽  
Power Losses ◽  
Running Speed ◽  
High Speed Machine

For a give air flux, the higher speed the fanner is running, the smaller the fanner’s size is. It is also well known that for a given power, the higher the machine’s running speed, the smaller the machine’s size has. If the fanner is geared to a high speed machine directly, the fan set’s volume will be sharply decreased. However, the heat dissipation of the high speed machine becomes a serious problem also due to the small size and high power loss density. Therefore, how to estimate accurately the power losses and temperature rise is a key issue for the high speed machine design. In this paper, the power losses and temperature of high speed PM machine for a fanner application are thoroughly investigated. And the test results of a prototype fan set partly shown the validity of the calculation method.

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.

On the Effect of Supplied Flow Rate to the Performance of a Tilting-Pad Journal Bearing: Static Load and Dynamic Force Measurements

2020 ◽  
Author(s):  
Luis San Andrés ◽  
Hardik Jani ◽  
Hussain Kaizar ◽  
Manish Thorat
Keyword(s):  
Flow Rate ◽  
Temperature Rise ◽  
Power Loss ◽  
Static Load ◽  
Dynamic Force ◽  
Shaft Speed ◽  
Tilting Pad ◽  
Oil Flow ◽  
Exit Temperature ◽  
Subsurface Temperatures

Abstract Rotating machinery relies on engineered tilting-pad journal bearings (TPJB) to provide static load support with minimal drag power losses, safe pad temperatures, and ensuring a rotordynamic stable rotor operation. End users focus on reducing the supplied oil flow rate into a bearing to both lower operational costs and to increase drive power efficiency. This paper presents measurements of the steady-state and dynamic forced performance of a TPJB whilst focusing on the influence of supplied oil flow rate, below and above a nominal condition (50% and 150%). The test bearing has five pads, slenderness ratio L/D = 0.4, spherical pivots with pad offset = 50% and a preload ∼ 0.40, with a clearance to radius ratio (Cr/R) ≈ 0.001 at room temperature. The bearing is installed under a load-between-pads (LBP) orientation and has a flooded housing with end seals. The test conditions include operation at various shaft surface speeds (32 m/s-85 m/s) and specific static loads from 0.17 MPa to 2.1 MPa. A turbine oil lubricates the bearing with a speed-dependent flow rate delivered at a constant supply temperature. Measurements obtained at a steady thermal equilibrium include the journal static eccentricity and attitude angle, the oil exit temperature rise, and the pads’ subsurface temperatures at various locations, circumferential and axial. The rig includes measurement of the drive torque and shaft speed to produce the bearing drag power loss. Dynamic force coefficients include stiffness, damping, and virtual-mass coefficients. As expected, the drag power and the lubricant temperature rise depend mainly on shaft speed rather than on applied load. A reduction in oil flow rate to 50% of its nominal magnitude causes a modest increase in journal eccentricity, a 15% reduction in drag power loss, a moderate raise (6°C) in pads’ subsurface temperatures, a slight increase (up to 6%) in the direct stiffnesses, and a decrease (up to 7%) in direct damping coefficients. Conversely, a 1.5 times increase in oil flow rate causes a slight increase (up to 9 %) in drag power loss, a moderate reduction of pads’ temperatures (up to 3°C), a maximum 5% reduction in direct stiffnesses, and a maximum 10% increase in direct damping. The paper also presents comparisons of the test results against predictions from a thermo-elasto-hydrodynamic lubrication model. In conclusion, a 50% reduced oil flow rate only causes a slight degradation in the test bearing static and dynamic force performance and does not make the bearing operation unsafe for tests with surface speed up to 74 m/s. As an important corollary, the measured bearing drag power differs from the conventional estimate derived from the product of the supplied flow rate, the lubricant specific heat and the oil exit temperature rise.

Effects of High-Operating Speeds on Tilting Pad Thrust Bearing Performance

1976 ◽  
Vol 98 (1) ◽  
pp. 73-79 ◽  
Author(s):  
J. W. Capitao ◽  
R. S. Gregory ◽  
R. P. Whitford
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Power Loss ◽  
High Speed ◽  
Thrust Bearing ◽  
Full Scale ◽  
Thrust Bearings ◽  
Tilting Pad ◽  
Speed Performance ◽  
Bearing Loads

A comparison of the high-speed performance characteristics of tilting-pad, self-equalizing type thrust bearings through two independent full-scale programs is reported. This paper presents experimental data on centrally pivoted, 6-pad, 267-mm (10 1/2-in.) and 304-mm (12-in.) O.D. bearings operating at shaft speeds up to 14000 rpm and bearing loads ranging up to 2.76 MPa (400 psi). Data presented demonstrate the effects of speed and loading on bearing power loss and metal temperatures. Included is a discussion of optimum oil supply flow rate based upon considerations of bearing pad temperatures and power loss values.

An Experimental Study of High-Speed Rotors Supported by Air-Lubricated Foil Bearings—Part 1: Rotation in Pressurized and Self-Acting Foil Bearings

1969 ◽  
Vol 91 (3) ◽  
pp. 477-493 ◽  
Author(s):  
L. Licht
Keyword(s):  
Experimental Study ◽  
Temperature Rise ◽  
High Speed ◽  
Air Gap ◽  
The Self ◽  
Wear Characteristics ◽  
Thrust Bearings ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Mode Of Operation

A high-speed rotor, supported by an air-lubricated foil bearing, is rotated in both the vertical and horizontal attitudes at speeds in excess of 60,000 rpm. The rotor is stable and free from “half-frequency” or “fractional-frequency” whirl instability encountered in conventional gas bearings. External pressurization is applied to separate the foil surfaces from the journal during the initial and final stages of rotation, with adequate self-acting support and foil separation established at relatively low transition speeds. In the pressurized mode of operation, the system is characterized by a series of ultra-harmonic resonances, of sharply defined frequencies, related by fractions to speeds of synchronous resonance. In the self-acting mode of operation, the response of the system to residual imbalance is influenced by both the foil bearing and by the pressurized thrust bearings. The magnitude of the air gap (clearance) is determined at various rotational speeds and compared with theoretically predicted results. The temperature rise of the foil with speed is measured at various locations in order to assess its contribution to clearance growth. The journal and foil surfaces are examined and it is found that the foil bearing is endowed with excellent wipe-wear characteristics.

Design of Novel Gas Foil Thrust Bearings and Test Validation in a High-Speed Test Rig

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Nguyen LaTray ◽  
Daejong Kim
Keyword(s):  
Power Loss ◽  
High Speed ◽  
Load Capacity ◽  
Experimental Studies ◽  
Design Feature ◽  
Outer Diameter ◽  
Test Rig ◽  
Thrust Bearings ◽  
Speed Test ◽  
Light Load

Abstract Small gas foil bearings (FBs) with shaft diameter below 25 mm can find many applications in air compressors for fuel cells, electrical turbo chargers, small unmanned air vehicles, turbo alternators, etc. These small machines are characterized by very light load to the radial FBs, and thus rotordynamics stability is more challenging than load capacity. However, a main challenge of gas foil thrust bearings (GFTBs) is how to increase the load capacity, and the challenge remains the same regardless of the size. In previous publications on experimental studies on GFTBs, the measured load capacity is well below the prediction due to challenges in testing as well as manufacturing of GFTBs. Difficulty in achieving the design load capacity often leads to increasing the bearing size in actual applications with penalty of higher power loss. This paper presents design feature of a novel GFTB with outer diameter of 38 mm and static performance up to 155 krpm under external load of 75 N using a high-speed test rig. The 38 mm GFTB presented in this paper is a three-layered structure for easy design and manufacturing, and the unique design feature allows easy scale down and scale up to different sizes. Reynolds equations for compressible gas and the two-dimensional thin plate model were adopted for fluid–structure interaction simulation to predict load capacity and power loss of the GFTB. The predicted power loss and load capacity agree well with the measurements.

High-Speed Performance of Tapered Roller Thrust Bearings With Various Lubricating Systems

1970 ◽  
Vol 92 (1) ◽  
pp. 97-101
Author(s):  
V. V. Naik ◽  
E. L. Keim ◽  
H. R. Neifert
Keyword(s):  
High Speed ◽  
Operating Temperature ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Flow Rates ◽  
Thrust Bearings ◽  
Oil Flow ◽  
Speed Performance ◽  
Tapered Roller ◽  
Lubricant Viscosity

Using high oil-flow rates, 6-in-bore tapered roller thrust bearings were operated in a speed range of 3600 fpm to 10800 fpm with loads up to 70,000 lb. Bearing operating temperature is considered to be the principal criterion of operation. The effect of lubricating systems, speed, load, oil-flow rates, lubricant viscosity, and oil-inlet temperature on the operating temperature is demonstrated. The test-rig results are generalized by means of dimensional analysis enabling the designer to predict operating temperature for various operating conditions of speed, load, oil-flow rates, and oil-inlet viscosity.

Effect of Bearing Structure on Oil-air Flow and Temperature of High Speed Ball Bearing by Combining Nonlinear Dynamic and CFD Model

2021 ◽  
Author(s):  
Song Deng ◽  
Guiqiang Zhao ◽  
Dongsheng Qian ◽  
Hua Lin
Keyword(s):  
Temperature Rise ◽  
Power Loss ◽  
High Speed ◽  
Volume Fraction ◽  
Air Flow ◽  
Ball Bearings ◽  
Cfd Model ◽  
Oil Film ◽  
High Speeds ◽  
Bearing Structure

Abstract To achieve effective cooling for high speed ball bearings, an investigation on the effect of bearing structure on oil-air flow and temperature inside bearing chamber is necessary. However, accurately defining boundary conditions of CFD model for high speed ball bearings has not been addressed completely. Adopting an improved dynamic model of bearings to calculate movements of balls and power loss to set the movement boundary and heat source of CFD model at high-low speeds and light-heavy loads. Then, rotational speed of cage and temperature of outer ring at various loads are tested to validate this proposed method. At high speeds, enlarging sealing degree of outlet not only reduces the temperature rise of bearings and improves the uniformity of temperature distribution, but also promotes the formation of oil-film on balls’ surfaces without increasing power loss. Yet it can reduce the temperature rise but can’t markedly improve the formation of oil-film at low and ultra-high speeds. Moreover, half birfield cage facing nozzle plays an important role in improving oil volume fraction inside the bearing cavity to reduce the temperature rise of bearings, and the next is birfield cage, they are again corrugated cage and half birfield cage back towards nozzle. These research results provide theoretical guidance for the improvement of bearing structure.

Sign in / Sign up

Export Citation Format

Share Document