scholarly journals Discussion: “Experimental Versus Theoretical Characteristics of a High-Speed Hybrid (Combination Hydrostatic and Hydrodynamic) Bearing” (Kurtin, K. Alan, Childs, D., San Andres, Luis, and Hale, K., 1993, ASME J. Tribol., 115, pp. 160–168)

1993 ◽  
Vol 115 (1) ◽  
pp. 168-168
Author(s):  
J. K. Scharrer
Keyword(s):  
High Speed ◽  
Hydrodynamic Bearing ◽  
Hybrid Combination ◽  
San Andres ◽  
Experimental Versus

Experimental Versus Theoretical Characteristics of a High-Speed Hybrid (Combination Hydrostatic and Hydrodynamic) Bearing

1993 ◽  
Vol 115 (1) ◽  
pp. 160-168 ◽  
Author(s):  
K. Alan Kurtin ◽  
D. Childs ◽  
Luis San Andres ◽  
K. Hale
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Test Facility ◽  
Navier Stokes ◽  
Radial Clearance ◽  
Hydrodynamic Bearing ◽  
Speed Test ◽  
Discharge Coefficients ◽  
Hybrid Combination ◽  
Numerical Predictions

The high-speed test facility designed and installed at Texas A&M to study water lubricated journal bearings has been successfully used to test statically an orifice compensated five-recess-hybrid (combination hydrostatic and hydrodynamic) bearing for two radial clearance configurations. Measurements of relative-bearing position, torque, recess pressure, flow rate, and temperature were made at speeds from 10,000 to 25,000 rpm and supply pressures of 6.89 MPa (1,000 psi), 5.52 MPa (800 psi), and 4.14 MPa (600 psi). For speeds of 10,000 and 17,500 rpm, the bearing load capacity was also investigated. A pitching instability of the bearing limited the number of test cases. A 2-dimensional, bulk-flow, Navier-Stokes numerical analysis program was used for all theoretical performance predictions. Orifice discharge coefficients used in the program were calculated from measured flow and pressure data. Reynolds numbers for flow within the bearing lands due to shaft rotation and recess pressurization ranged from 6700 to 16,500. Predictions sensitivity to ±10 percent changes in the input parameters was investigated. Results showed that performance prediction sensitivities are high for changes in discharge coefficients and negligible for changes in relative roughness. The numerical predictions of relative bearing position, recess pressure, flowrate, and torque are very accurate, provided the selected orifice discharge coefficients are correct.

Rotordynamic Evaluation of a Roughened-Land Hybrid Bearing

1999 ◽  
Vol 121 (1) ◽  
pp. 133-138 ◽  
Author(s):  
Patrice Fayolle ◽  
Dara W. Childs
Keyword(s):  
High Speed ◽  
Factor Model ◽  
Attractive Alternative ◽  
Good Prediction ◽  
Ball Bearings ◽  
Stiffness Coefficients ◽  
Leakage Flow Rate ◽  
Hybrid Bearing ◽  
San Andres ◽  
Rotor Dynamic

Hybrid bearings represent an attractive alternative to ball bearings for use in highspeed cryogenic turbopumps. However, the internally-developed cross-coupled forces can generate instabilities responsible for a speed limitation of the machine. To reduce these forces and raise the onset speed of instability, the use of deliberately-roughened stators, already successfully tested for liquid “damper” seals, is investigated. Rotor-dynamic results are presented for a five-pocket orifice-compensated hole-pattern-land hybrid bearing tested with water at high speed and high pressure. Experimental data show a good prediction of leakage flow rate and direct damping but a significant improvement in stability compared to a conventional smooth-land hybrid bearing, resulting in an elevation of the onset speed of instability. Comparisons between measurements and predictions from a code developed by San Andres (1994) shows good predictions for flowrate and direct damping but an over prediction for the direct and cross-coupled stiffness coefficients by about 30 and 50 percent, respectively. The use of the Moody friction-factor model is thought to be mainly responsible for the poorer predictions of stiffness coefficients.

Material Considerations for High Temperature Tilting Pad Gas Bearings

1968 ◽  
Vol 90 (4) ◽  
pp. 818-828 ◽  
Author(s):  
S. F. Murray ◽  
M. B. Peterson
Keyword(s):  
High Temperature ◽  
Contact Area ◽  
High Speed ◽  
Contact Problems ◽  
Sliding Contact ◽  
Gas Bearings ◽  
Hydrodynamic Bearing ◽  
Tilting Pad ◽  
Short Time

This paper is concerned with the sliding contact problems encountered in tilting pad gas bearings operating at temperatures up to 1400 deg F. Both the pivots and the bearing surfaces are considered. Short time experimental evaluations of pivot damage are summarized. The results of start-stop and high-speed rub tests on a single tilting pad hydrodynamic bearing are also described. Based on the results obtained to date, damage-resistant coatings are available for use on the bearing surfaces at high temperature. There are also suitable pivot materials, but the pivot must be properly designed to minimize slip in the contact area.

Hydrodynamic bearing with non-uniform spiral grooves for high-speed HDD spindle

2009 ◽  
Author(s):  
Yo Arakawa ◽  
Shinichi Ikeda ◽  
Tomoko Hirayama ◽  
Takashi Matsuoka ◽  
Noriaki Hishida
Keyword(s):  
High Speed ◽  
Hydrodynamic Bearing ◽  
Spiral Grooves

Analysis on Dynamic Performance of Hydrodynamic Tilting-Pad Gas Bearings Using Partial Derivative Method

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Yang Lihua ◽  
Qi Shemiao ◽  
Yu Lie
Keyword(s):  
Analytical Method ◽  
Gas Turbines ◽  
High Speed ◽  
Dynamic Performance ◽  
Gas Bearings ◽  
Dynamic Coefficients ◽  
Tilting Pad ◽  
Dynamic Performances ◽  
Perturbation Frequency ◽  
San Andres

Tilting-pad gas bearings are widely used in high-speed rotating machines due to their inherent stability characteristics. This paper advances the analytical method for prediction of the dynamic performances of tilting-pad gas bearings. The main advantage of the analytical method is that the complete set of dynamic coefficients of tilting-pad gas bearings can be obtained. The predictions show that the perturbation frequency has the strong effects on the dynamic coefficients of gas bearings. In general, at lower perturbation frequency, the equivalent direct stiffness coefficients increase with frequency, whereas equivalent direct damping coefficients dramatically reduce. For higher perturbation frequency, the dynamic coefficients are nearly independent of the frequency. Moreover, the equivalent dynamic coefficients of four-pad tilting-pad gas bearing obtained by the method in this paper are in good agreement with those obtained by Zhu and San Andres [(2007), “Rotordynamic Performance of Flexure Pivot Hydrostatic Gas Bearings for Oil-Free Turbomachinery,” ASME J. Eng. Gas Turbines Power, 129(4), pp. 1020–1027] in the published paper. The results validate the feasibility of the method presented in this paper in calculating the dynamic coefficients of gas-lubricated tilting-pad bearings.

Performance of Air-Lubricated Hydrodynamic Bearing Spindles for Laser Scanners

1991 ◽  
Vol 113 (3) ◽  
pp. 609-614 ◽  
Author(s):  
K. Tanaka ◽  
H. Muraki
Keyword(s):  
High Speed ◽  
High Performance ◽  
Experimental Results ◽  
Hydrodynamic Bearing ◽  
Vibration Resistance ◽  
High Speeds ◽  
Laser Printers ◽  
Laser Scanners

This paper reports on the performance of air-lubricated bearing spindles for high-speed laser scanners using newly developed bearings. Experimental results confirmed that these spindles have adequate performance including floating stability, endurance, vibration-resistance at high-speeds, and start-stop endurance for laser scanners. These spindles are already mass-produced and used in laser printers and digital color copiers, so their high performance and endurance are proven.

An Experimental Study of Nonlinear Oil-Film Forces in a Tilting-Pad Journal Bearing

2015 ◽  
Author(s):  
Phuoc Vinh Dang ◽  
Steven Chatterton ◽  
Paolo Pennacchi ◽  
Andrea Vania ◽  
Filippo Cangioli
Keyword(s):  
High Speed ◽  
Nonlinear Models ◽  
Reaction Force ◽  
Taylor Series Expansion ◽  
Test Model ◽  
Oil Film ◽  
Hydrodynamic Bearing ◽  
Dynamic Coefficients ◽  
Stiffness And Damping ◽  
Tilting Pad Journal Bearing

Journal bearings have been widely used in high-speed rotating machinery. The dynamic coefficients of oil-film force affect the machine unbalance response and machine stability. The oil-film force of hydrodynamic bearing is often characterized by a set of linear stiffness and damping coefficients. However the linear oil-film coefficients with respect to an equilibrium position of the journal are inaccurate when the bearing system vibrates with large amplitudes due to a dynamic load. The study on nonlinear oil-film forces is still rare and most papers are confined to theoretical analyses. The purpose of this paper is to derive some new non-linear force models (28-co., 24-co. and 36-co. models) to identify these dynamic coefficients based on experimental data. The fundamental test model is obtained from a Taylor series expansion of bearing reaction force. Tests were performed with a nominal diameter of 100mm and a length–to–diameter ratio of 0.7 using a suitable test rig in which it is possible to apply the static load in any direction. The results show that these three models are feasible to identify the oil-film forces in which the second-order oil-film coefficients received from the 24-co. model are more stable compared to those of other two nonlinear models.

Hydrostatic-Hydrodynamic Bearing Design of High-Speed Camshaft Grinding

2012 ◽  
Vol 590 ◽  
pp. 385-390 ◽  
Author(s):  
Yu Huang ◽  
Shang Zhang ◽  
Yi Lin Liu ◽  
Bi Peng ◽  
Guo Jun Zhang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Speed ◽  
Analysis Software ◽  
Element Analysis ◽  
Linear Speed ◽  
Hydrodynamic Bearing ◽  
Bearing Stiffness ◽  
Bearing Design ◽  
The Relationship

Conditions for changing acceleration and force spindle when the high-speed high-precision camshaft grinding with the action of follow grinding and the constant linear speed grinding，a step-pocket cavity hydrostatic -hydrodynamic bearings is designed to meet this precision camshaft grinding, and the relationship between eccentricity and bearing stiffness, load are analyzed by the method of finite-element analysis with fluid finite element analysis software.

Mathematical formulation of the film thickness in a multi-pad externally adjustable hydrodynamic bearing using the transformation technique

2021 ◽  
Vol 21 (3) ◽  
pp. 525-534
Author(s):  
A. Ganesha ◽  
Pai Raghuvir ◽  
S.M. Abdul Khader
Keyword(s):  
Film Thickness ◽  
High Speed ◽  
Mathematical Formulation ◽  
Approximation Error ◽  
Conventional Technique ◽  
Fine Tuning ◽  
Transformation Technique ◽  
Hydrodynamic Bearing ◽  
Thickness Profile ◽  
Projection Approximation

Instability problem of a hydrodynamic plain journal bearing at higher speeds is conventionally resolved by using the non-circular bearings. High speed precision rotating shafts demands accurate positioning of the journal centres. A multi-pad adjustable bearing is a non-circular bearing, provides a fine-tuning option of the journal centre by continuously changing the bearing profile. In the present study, the bearing has a configuration of four bearing pads that are adjustable both in the radial and tilt directions. The fluid film thickness profile is conventionally obtained using the trigonometric relations, which has computational limitations, especially in multi-pad adjustable bearings. In this investigation, the film thickness profile of a multi-pad adjustable bearing is mathematically formulated using the transformation technique. The results obtained are compared with those available in the literature for a similar bearing. The observation shows that transformation technique eliminates the projection approximation error present in the conventional technique.

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