scholarly journals A Test Apparatus and Facility to Identify the Rotordynamic Coefficients of High-Speed Hydrostatic Bearings

1994 ◽  
Vol 116 (2) ◽  
pp. 337-343 ◽  
Author(s):  
Dara Childs ◽  
Keith Hale
Keyword(s):  
High Speed ◽  
Static Load ◽  
Reynolds Numbers ◽  
Added Mass ◽  
Journal Bearings ◽  
Test Fluid ◽  
Test Apparatus ◽  
Operating Characteristics ◽  
Rotordynamic Coefficients ◽  
A Current

A facility and apparatus are described which determine stiffness, damping, and added-mass rotordynamic coefficients plus steady-state operating characteristics of high speed hydrostatic journal bearings. The apparatus has a current top speed of 29800 rpm with a bearing diameter of 7.62 cm (3 in.). Purified warm water, 55°C (130°F), is used as a test fluid to achieve elevated Reynolds numbers during operation. The test-fluid pump yields a bearing maximum inlet pressure of 6.9 Mpa (1000 psi). Static load on the bearing is independently controlled and measured. Orthogonally mounted external shakers are used to excite the test stator in the direction of, and perpendicular to, the static load. The apparatus can independently calculate all rotordynamic coefficients at a given operating condition.

Experimental Test Results for Four High-Speed, High-Pressure, Orifice-Compensated Hybrid Bearings

1994 ◽  
Vol 116 (1) ◽  
pp. 147-153 ◽  
Author(s):  
N. M. Franchek ◽  
D. W. Childs
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Pressure Ratio ◽  
Reynolds Numbers ◽  
Orifice Diameter ◽  
Test Results ◽  
Rotordynamic Coefficients ◽  
Geometric Configurations ◽  
Overall Performance ◽  
Mass Terms

In this study, four hybrid bearings having different geometric configurations were experimentally tested for their static and dynamic characteristics, including flowrate, load capacity, rotordynamic coefficients, and whirl frequency ratio. The four bearings included a square-recess, smooth-land, radial-orifice bearing (baseline), a circular-recess bearing, a triangular-recess bearing, and an angled-orifice bearing. Each bearing had the same orifice diameter rather than the same pressure ratio. Unique to these test results is the measurement of the added mass terms, which became significant in the present tests because of high operating Reynolds numbers. Comparisons of the results were made between bearings to determine which bearing had the best performance. Based on the parameters of interest, the angled-orifice bearing has the most favorable overall performance.

Paper 2: Hydrodynamic Stability of the Flow between Eccentric Rotating Cylinders with Axial Flow: Visual Observations

1969 ◽  
Vol 184 (12) ◽  
pp. 10-17 ◽  
Author(s):  
J. E. R. Coney ◽  
F. R. Mobbs
Keyword(s):  
Hydrodynamic Stability ◽  
High Speed ◽  
Marked Effect ◽  
Axial Flow ◽  
Journal Bearings ◽  
Test Fluid ◽  
Taylor Vortices ◽  
Annulus Flow ◽  
Flow Through ◽  
Paint Pigment

The influence of side leakage on the onset of Taylor vortices in high-speed journal bearings is studied by observing the effects of varying the eccentricity of, and the axial flow through, an annulus. The apparatus permits of both sharp and smooth entries to the annulus. Flow visualization is achieved by means of aluminium paint pigment suspended in the test fluid. It is shown that both the eccentricity and the axial flow have a marked effect on the critical Taylor number. Evidence is presented for the co-existence of two systems of vortices within the annulus.

Theoretical and Experimental Comparisons for Rotordynamic Coefficients of a High-Speed, High-Pressure, Orifice-Compensated Hybrid Bearing

1995 ◽  
Vol 117 (2) ◽  
pp. 285-290 ◽  
Author(s):  
Nancy M. Franchek ◽  
Dara W. Childs ◽  
Luis San Andres
Keyword(s):  
High Pressure ◽  
High Speed ◽  
Discharge Coefficient ◽  
Test Fluid ◽  
Test Results ◽  
Rotordynamic Coefficients ◽  
Hybrid Bearing ◽  
San Andres ◽  
Experimental Comparisons ◽  
Good Agreement

Comparisons are presented between measurements and predictions for a 76.2 mm diameter, high-speed (24,600 rpm), high-pressure (7.0 MPa), hybrid bearings using warm (54°C) water as a test fluid. “Hybrid” refers to combined hydrostatic and hydrodynamic action. Test results are presented for an orifice-fed, square-recess configuration with five recesses. Data are provided for rotordynamic coefficients including direct and cross-coupled stiffness, direct damping, direct added-mass coefficients, and the whirl-frequency ratio. Experimental results are compared to predictions from an analysis by San Andres (1990a), which accounts for both temporal and convective acceleration terms in the fluid film. San Andres’ development uses an orifice discharge coefficient to model the pressure drop from supply pressure to recess pressure. With experimentally determined discharge-coefficient values as input, good agreement is obtained between theory and experiment. However, predictions are sensitive to changes in the orifice discharge coefficients.

Calculation of High Speed Multilobe Journal Bearings

2005 ◽  
Author(s):  
S. Strzelecki ◽  
J. Piechna
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Theoretical Calculations ◽  
Relative Length ◽  
Journal Bearings ◽  
Operating Characteristics ◽  
Clearance Ratio ◽  
Oil Film ◽  
Adiabatic Flow ◽  
Gear Trains

The bearing systems of turbocompressors, compressors and turbine gear trains consist the multilobe journal bearings. In these bearings, high speed of journal causes, that the oil film of bearing is not laminar but turbulent one. Turbulent oil film affects the bearing operating characteristics. Calculations in this case can not be carried-out on the condition of laminar oil film but on the assumption of turbulent one. The paper introduces theoretical calculations of the high speed multilobe journal bearing affected by turbulent oil film. For the 4-lobe journal bearing the different values of lobe clearance ratio and relative length of the bearing were assumed. The Reynolds, energy and viscosity equations were solved numerically on the assumption of incompressible lubricant and the turbulent adiabatic flow of oil in the bearing gap.

Improvement of Operating Characteristics of High-Speed Hydrodynamic Journal Bearings by Optimum Design: Part I— Formulation of Methodology and Its Application to Elliptical Bearing Design

2000 ◽  
Vol 123 (2) ◽  
pp. 305-312 ◽  
Author(s):  
H. Hashimoto ◽  
K. Matsumoto
Keyword(s):  
Optimum Design ◽  
High Speed ◽  
Optimization Technique ◽  
Orientation Angle ◽  
Journal Bearings ◽  
Graphical Form ◽  
Operating Characteristics ◽  
Design Variables ◽  
Wide Range ◽  
Bearing Design

This paper describes the optimum design methodology for improving operating characteristics of hydrodynamic journal bearings and its application to elliptical journal bearing design used in high-speed rotating machinery. The hybrid optimization technique combining the direct search method and the successive quadratic programming is applied effectively to find the optimum solutions. In the optimum design of elliptical journal bearings, the design variables such as vertical and horizontal radial clearances, bearing length-to-diameter ratio and bearing orientation angle are determined to minimize the objective function defined by the weighted sum of maximum averaged oil film temperature rise, leakage flow rate, and the inversion of whirl onset speed of the journal under many constraints. The results obtained are shown in graphical form for a wide range of journal rotational speed. Comparing the optimized operating characteristics with the characteristics calculated from the random selected design variables, the effectiveness of optimum design is clarified.

scholarly journals Improvement of Tilting-Pad Journal Bearing Operating Characteristics by Application of Eddy Grooves

Lubricants ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 18
Author(s):  
Eckhard Schüler ◽  
Olaf Berner
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Load Capacity ◽  
Fluid Film ◽  
Operating Characteristics ◽  
Fluid Film Bearings ◽  
Tilting Pad ◽  
Bearing Load ◽  
Bearing Loads ◽  
Tilting Pad Journal Bearing

In high speed, high load fluid-film bearings, the laminar-turbulent flow transition can lead to a considerable reduction of the maximum bearing temperatures, due to a homogenization of the fluid-film temperature in radial direction. Since this phenomenon only occurs significantly in large bearings or at very high sliding speeds, means to achieve the effect at lower speeds have been investigated in the past. This paper shows an experimental investigation of this effect and how it can be used for smaller bearings by optimized eddy grooves, machined into the bearing surface. The investigations were carried out on a Miba journal bearing test rig with Ø120 mm shaft diameter at speeds between 50 m/s–110 m/s and at specific bearing loads up to 4.0 MPa. To investigate the potential of this technology, additional temperature probes were installed at the crucial position directly in the sliding surface of an up-to-date tilting pad journal bearing. The results show that the achieved surface temperature reduction with the optimized eddy grooves is significant and represents a considerable enhancement of bearing load capacity. This increase in performance opens new options for the design of bearings and related turbomachinery applications.

Development and Validation of a Three-Dimensional Multiphase Flow CFD Analysis for Journal Bearings in Steam and Heavy Duty Gas Turbines

2012 ◽  
Author(s):  
Stephan Uhkoetter ◽  
Stefan aus der Wiesche ◽  
Michael Kursch ◽  
Christian Beck
Keyword(s):  
Experimental Data ◽  
Multiphase Flow ◽  
Gas Turbines ◽  
High Speed ◽  
Three Dimensional ◽  
Air Entrainment ◽  
Journal Bearings ◽  
Heavy Duty ◽  
Present Contribution ◽  
Two Phase

The traditional method for hydrodynamic journal bearing analysis usually applies the lubrication theory based on the Reynolds equation and suitable empirical modifications to cover turbulence, heat transfer, and cavitation. In cases of complex bearing geometries for steam and heavy-duty gas turbines this approach has its obvious restrictions in regard to detail flow recirculation, mixing, mass balance, and filling level phenomena. These limitations could be circumvented by applying a computational fluid dynamics (CFD) approach resting closer to the fundamental physical laws. The present contribution reports about the state of the art of such a fully three-dimensional multiphase-flow CFD approach including cavitation and air entrainment for high-speed turbo-machinery journal bearings. It has been developed and validated using experimental data. Due to the high ambient shear rates in bearings, the multiphase-flow model for journal bearings requires substantial modifications in comparison to common two-phase flow simulations. Based on experimental data, it is found, that particular cavitation phenomena are essential for the understanding of steam and heavy-duty type gas turbine journal bearings.

Comparative Evaluation of MoS2 and WS2 as Powder Lubricants in High Speed, Multi-Pad Journal Bearings

1999 ◽  
Vol 121 (3) ◽  
pp. 625-630 ◽  
Author(s):  
C. Fred Higgs ◽  
Crystal A. Heshmat ◽  
Hooshang Heshmat
Keyword(s):  
Comparative Evaluation ◽  
High Speed ◽  
Solid Lubricants ◽  
Extreme Environment ◽  
Journal Bearings ◽  
Lubricating Film ◽  
Constant Friction ◽  
Traction Coefficient ◽  
Limiting Value ◽  
Selection Of

As part of a program to develop solid/powder-lubricated journal bearings, a comparative evaluation has been performed to aid in determining whether MoS2 and WS2 powder are suitable lubricants for high-speed, extreme-environment multi-pad journal bearings. Plots of traction coefficients, friction, frictional power loss, and bearing pad temperature are presented as a means for comparing various powder lubricants. This paper primarily focuses on experiments carried out on a three-pad journal bearing and a disk-on-disk tribometer. Results showed that MoS2 traction curves resemble that of SAE 10 synthetic oil. Unlike liquid lubricants, powder films have a limiting shear strength property. Once the powder reaches this limiting value, the maximum traction coefficient is limited and the powder essentially shears along sliding walls. Experimental traction data shows evidence of this property in various powders. The thermal performance of the bearing was evaluated at speeds up to 30,000 rpm and loads up to 236 N. Although WS2 displayed constant friction coefficient and low temperature with increasing dimensionless load, MoS2 exhibited frictional behavior resembling that of a hydrodynamic lubricating film. In this paper, an attempt has been made to provide a criterion for the selection of solid lubricants for use in those tribosystems that may be operated in a high speed/load regime (i.e., high strain rates) as an alternative yard stick to conventional comparative approaches.

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