Behavior of an Oscillating Oil Squeeze Film

1986 ◽  
Vol 108 (4) ◽  
pp. 639-644 ◽  
Author(s):  
D. W. Parkins ◽  
J. H. Woollam
Keyword(s):  
Film Thickness ◽  
Lower Surface ◽  
Squeeze Film ◽  
Oil Film ◽  
Pressure Transducers ◽  
Experimental Apparatus ◽  
Computer Controlled ◽  
Oscillatory Cycle ◽  
Steady Force ◽  
Oil Film Pressure

This paper records observations of the behavior of an oil film subject to an oscillatory squeeze motion of its containing surfaces. In the experimental apparatus, the square upper surface oscillated at a frequency within the range 5–45 Hz and contained two pressure transducers. A fixed transparent lower surface facilitated viewing of cavitation patterns and their position relative to the pressure transducers. A computer controlled technique enabled these patterns to be photographed at any selected point in the oscillatory cycle, and synchronized with the corresponding instantaneous oil film pressure and thickness. The effect is given of vibratory amplitude, frequency and initial oil film thickness upon the steady force generated by the oscillatory squeeze motion. A previously identified cavitation regime has been shown to be more complex than hitherto supposed. Four sub-regimes have been tentatively identified. Their characteristics are described, together with photographs of typical sequences of cavitation patterns in each subregime, at identified times in the pressure and film thickness cycle. The effects of surrounding oil depth upon the vibratory amplitude at which cavitation first appears, is described. Descriptions are given of the sub-regime appearing at onset, and any changes thereto appearing with further increases in vibratory amplitude.

Cavitation in an Oscillatory Oil Squeeze Film

1984 ◽  
Vol 106 (3) ◽  
pp. 360-365 ◽  
Author(s):  
D. W. Parkins ◽  
R. May-Miller
Keyword(s):  
Cavitation Bubble ◽  
Lower Surface ◽  
Squeeze Film ◽  
Film Pressure ◽  
Oil Film ◽  
Experimental Apparatus ◽  
Time Histories ◽  
Time Cycle ◽  
Oscillatory Cycle ◽  
Oil Film Pressure

This paper records observed features of cavitation arising in an oscillatory oil squeeze film. In the experimental apparatus, two nondeformable surfaces contained the oil film. The square upper surface oscillated, normally to the oil film, at any frequency between 5 and 50 Hz. A transparent lower surface together with a viewing and synchronising system enabled cavitation bubble patterns in the oil film to be observed and photographed at any point in the oscillatory cycle. Three different behavioral regimes (designated 1, 2, and 3) have been observed, each characterized by the method of forming cavitation bubbles together with particular features in the oil film pressure, thickness and bubble extent-time cycle. Descriptions are given of the salient features of each regime, and the transition from one to another. The paper contains photographs of cavitation bubble patterns at important points in the typical oscillatory cycles together with their location in the oil film pressure and thickness time histories.

Characteristics of an Oil Squeeze Film

1982 ◽  
Vol 104 (4) ◽  
pp. 497-502 ◽  
Author(s):  
D. W. Parkins ◽  
W. T. Stanley
Keyword(s):  
Steady State ◽  
Film Thickness ◽  
Squeeze Film ◽  
Normal Velocity ◽  
Oil Film ◽  
Pressure Fields ◽  
Time Histories ◽  
The Mean ◽  
Oscillatory Cycle ◽  
Phase Differences

This paper presents both theoretically and experimentally determined characteristics of an oil squeeze film. In the experimental arrangement, an oil film was contained within two plane surfaces having only normal oscillatory relative motion. The effects of initial oil film thickness, peak to peak amplitude, and frequency of oscillation were measured. A finite difference treatment gave theoretical oil pressure fields and forces for any specified normal velocity. Comparisons were made between the pressure measured at one position and its theoretical counterpart over an oscillatory cycle. Subzero oil film pressures were measured. A steady state (in addition to the dynamic) oil film force was identified, whose magnitude and direction depend on the mean oil film thickness, oscillatory amplitude, and frequency. A region of unstable behavior was found. Theory agreed reasonably with practice, but over estimated some oil film pressures and gave time histories which exhibited phase differences with the measured counterpart. These differences were not explained by including the measured pad misalignment in the theoretical model. Further extensions to the theory are suggested.

Influence of Surface Waviness on the Thermal Elastohydrodynamic Lubrication of an Eccentric-Tappet Pair

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
J. Wang ◽  
C. H. Venner ◽  
A. A. Lubrecht
Keyword(s):  
Film Thickness ◽  
Elastohydrodynamic Lubrication ◽  
Surface Waviness ◽  
Film Pressure ◽  
Oil Film ◽  
Working Cycle ◽  
Temperature Oscillations ◽  
Minimum Film Thickness ◽  
Traction Coefficient ◽  
Oil Film Pressure

The effect of single-sided and double-sided harmonic surface waviness on the film thickness, pressure, and temperature oscillations in an elastohydrodynamically lubricated eccentric-tappet pair has been investigated in relation to the eccentricity and the waviness wavelength. The results show that, during one working cycle, the waviness causes significant fluctuations of the oil film, pressure, and temperature, as well as a reduction in minimum film thickness. Smaller wavelength causes more dramatic variations in oil film. The fluctuations of the pressure, film thickness, temperature, and traction coefficient caused by double-sided waviness are nearly the same compared with the single-sided waviness, but the variations are less intense.

Interferometry-based measurements of oil-film thickness

2001 ◽  
Vol 215 (3) ◽  
pp. 243-259 ◽  
Author(s):  
O Marklund ◽  
L Gustafsson
Keyword(s):  
Film Thickness ◽  
Measurement Errors ◽  
Phase Measurement ◽  
Elastohydrodynamic Lubrication ◽  
Oil Film ◽  
Interferometric Phase ◽  
Experimental Apparatus ◽  
Colour Parameters ◽  
Computer Based ◽  
The Absolute

Measurement of the thickness of thin lubricant films separating rotating surfaces in elastohydrodynamic experiments presents some challenging problems. The nature of the experimental apparatus inhibits the use of most commonly applied interferometric phase measurement methods. Also the absolute thickness of the separating film must be determined, as opposed to relative distances that would be sufficient in most other measurement scenarios where interferometry methods are used. In this paper, computer-based analysis of interferograms recorded using an elastohydrodynamic lubrication Fitzeu interferometer (a so-called ball-and-disc apparatus) is discussed, the main objective being to extract the absolute oil-film thickness. Intensity based methods (most importantly, calibration look-up procedures where colour parameters from recorded dynamic interferograms are compared with table values corresponding to known film thicknesses, but also a phase measurement approach based on multi-channel interferometry using trichromatic light) are described. A discussion regarding compensation for measurement errors due to the pressure dependence of the refractive index of the lubricant is also included.

Oil Film Properties of Three Oil Wedge Sliding Bearing and its Effect to the Rotor Stability

2012 ◽  
Vol 614-615 ◽  
pp. 469-474
Author(s):  
Ai Ping Zhang ◽  
Sheng Qiang Lin
Keyword(s):  
Film Thickness ◽  
Navier Stokes ◽  
Film Properties ◽  
Navier Stokes Equation ◽  
Sliding Bearing ◽  
Film Pressure ◽  
Oil Film ◽  
Wedge Sliding ◽  
Oil Film Pressure ◽  
Pressure Characteristics

Calculating navier-stokes equation to study oil film pressure characteristics of three oil wedge bearing by using CFD software. Studied how to the three oil wedge sliding bearing effect on rotor stability, and analyzing oil film pressure characteristics of three oil wedge sliding bearing and cylindrical bearing. The results showed that three oil wedge bearing is much more stable than the cylindrical bearing, it is more advantageous to the running rotor and unit at stable working than the cylindrical bearing in the same oil film thickness and inlet pressure.

Research on the Static and Dynamic Characteristics of Misaligned Journal Bearing Considering the Turbulent and Thermohydrodynamic Effects

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Guohui Xu ◽  
Jian Zhou ◽  
Haipeng Geng ◽  
Mingjian Lu ◽  
Lihua Yang ◽  
...  
Keyword(s):  
Film Thickness ◽  
Dynamic Characteristics ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Static And Dynamic Characteristics ◽  
Oil Film ◽  
Stiffness And Damping ◽  
Film Stiffness ◽  
Journal Misalignment ◽  
Oil Film Pressure

Journal misalignment usually exists in journal bearings that affect nearly all the bearings static and dynamic characteristics including minimum oil film thickness, maximum oil film pressure, maximum oil film temperature, oil film stiffness, and damping. The main point in this study is to provide a comprehensive analysis on the oil film pressure, oil film temperature, oil film thickness, load-carrying capacity, oil film stiffness, and damping of journal bearing with different misalignment ratios and appropriately considering the turbulent and thermo effects based on solving the generalized Reynolds equation and energy equation. The results indicate that the oil thermo effects have a significant effect on the lubrication of misaligned journal bearings under large eccentricity ratio. The turbulent will obviously affect the lubrication of misaligned journal bearings when the eccentricity or misalignment ratio is large. In the present design of the journal bearing, the load and speed become higher and higher, and the eccentricity and misalignment ratio are usually large in the operating conditions. Therefore, it is necessary to take the effects of journal misalignment, turbulent, and thermal effect into account in the design and analysis of journal bearings.

Experimental and Analytical Investigation of Squeeze Film Bearing Damper Forces Induced by Offset Circular Whirl Orbits

1978 ◽  
Vol 100 (3) ◽  
pp. 549-557 ◽  
Author(s):  
P. N. Bansal ◽  
D. H. Hibner
Keyword(s):  
Basic Research ◽  
Aircraft Engine ◽  
Analytical Investigation ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Test Results ◽  
Simple Method ◽  
Oil Film ◽  
Pressure Transducers ◽  
Pressure Profiles

A basic research program was conducted to investigate the hydrodynamic forces of a squeeze film bearing damper. These forces were induced by controlled offset circular whirl orbits of the damper journal. The orbits were mechanically produced by eccentric damper rings and cams in a specially designed, end sealed test rig. Aircraft engine damper geometry and operating conditions were simulated. The instantaneous circumferential pressure profiles, for specific orbits, were measured by eight high response pressure transducers. From these data, twelve composite pressure plots were developed; each was numerically integrated to determine the damper forces corresponding to every 30 deg position of the damper center, i.e., 0–360 deg. The variations in oil film thickness data were monitored via two proximity probes. A numerical method which uses the proximity test data and the damper geometry to calculate the instantaneous values of damper center eccentricity (e), phase angle (φ), radial velocity (e˙), and whirl velocity (φ˙) is presented. These test values are required to compare theory with test. Since the data reduction for offset orbits is extremely complicated, this simple method was found to be very useful in analyzing the test results. Test results for pressure profiles as well as damper forces were compared with theoretical predictions. Agreement was good. The analysis is based on “long bearing” solution of Reynolds equation and includes the effect of inlet and cavitation pressures. For the cavitated oil film, inlet pressure was shown to have important effect on damper forces.

Viscoplastic Lubrication Analysis in a Metal-Rolling Inlet Zone Using Parametric Quadratic Programming

2005 ◽  
Vol 127 (3) ◽  
pp. 605-610 ◽  
Author(s):  
C. W. Wu ◽  
G. J. Ma ◽  
H. S. Sun
Keyword(s):  
Quadratic Programming ◽  
Film Thickness ◽  
Slip Velocity ◽  
Wall Slip ◽  
Rolling Speed ◽  
Parametric Quadratic Programming ◽  
Film Pressure ◽  
Oil Film ◽  
Inlet Zone ◽  
Oil Film Pressure

A mathematical programming solution based on finite element method is used to analyze wall slip of viscoplastic lubrication in a metal-rolling inlet zone. Slip velocity can be directly obtained by parametric quadratic programming without an iterative process between the oil film pressure and the slip velocity. It is found that wall slip causes the oil film thickness to decrease dramatically. The initial limiting shear strength and proportional constant of the viscoplastic lubricant have a larger effect on the oil film pressure than the rolling speed. The nonsensitivity of oil film thickness to the rolling speed is a great particular advantage to metal-rolling processing.

Numerical Model of Journal Bearing Lubrication Considering a Bending Stiffness Effect

2013 ◽  
Vol 284-287 ◽  
pp. 854-860
Author(s):  
Juh Wan Choi ◽  
Seong Su Kim ◽  
Sung Soo Rhim ◽  
Jin Hwan Choi
Keyword(s):  
Numerical Model ◽  
Film Thickness ◽  
Journal Bearing ◽  
Elastohydrodynamic Lubrication ◽  
Bending Stiffness ◽  
Thickness Variation ◽  
Lubrication System ◽  
Film Pressure ◽  
Oil Film ◽  
Oil Film Pressure

An analysis for operating characteristics of journal bearing lubrication system is performed based on the numerical model. Dynamic bearing lubrication characteristics such as oil film pressure and thickness distribution can be analyzed through a numerical model with an integration of elastohydrodynamics and multi-flexible-body dynamics (MFBD). In particular, the oil film thickness variation by elastic deformation is considered in the elastohydrodynamic analysis by applying the bending stiffness effect of journal. And the oil film thickness variation by the bending stiffness effect is applied to the fluid governing equations to calculate the oil film pressure in the elastohydrodynamic lubrication region. A series of process proposed in this study is available for the analysis of realistic elastohydrodynamic lubrication phenomenon. Also, a numerical example for the journal bearing lubrication system is demonstrated and compared with the experimental results. The numerical results considering the bending stiffness effect show a good agreement with the experimental results.

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