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.

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 Bubble Dynamics Induced by Hydrodynamic Pressure Oil Film in Ultrasonic Vibration Honing

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Ce Guo ◽  
XiJing Zhu ◽  
Jia Liu ◽  
Dan Zhang
Keyword(s):  
Ultrasonic Vibration ◽  
Cavitation Bubble ◽  
Bubble Dynamics ◽  
Prediction Method ◽  
Hydrodynamic Pressure ◽  
Ultrasonic Frequency ◽  
Film Pressure ◽  
Oil Film ◽  
Cavitation Effect ◽  
Oil Film Pressure

During ultrasonic vibration honing (UVH), a thin hydrodynamic oil film formed can seriously affect the cavitation effect in the grinding fluid, but the mechanism is still unclear now. Based on the hydrodynamics theory, a revised cavitation bubble model with oil film pressure is developed, and it has been calculated by the four-order Runge–Kutta method. The calculation results show that the oil film pressure under UVH is a positive–negative alternant pulse pressure, and it can induce the secondary expansion of the bubble, leading to double microjets during the process of the bubble collapsing. The effects of ultrasonic amplitude, ultrasonic frequency, oil film height, and reciprocation speed of the honing stone on the bubble dynamics are discussed. With the increase of ultrasonic amplitude, the amplitude of the bubble expansion is increased, and the oscillation interval is extended. As increasing normalized oil film height, the variation of the bubble first expansion is slight, while the amplitude of the bubble secondary expansion is reduced and the oscillation interval is also shortened. The main effect of ultrasonic frequency and reciprocation speed of the honing stone on the bubble dynamics is connected with the secondary bubble expansion. The bubble secondary expansion is decreased with the increasing reciprocation speed of the honing stone, ultrasonic frequency, and oil film height. The results of the simulations are consistent with the surface roughness measurements well, which provides a theoretical prediction method of cavitation bubbles control.

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.

Investigation of Cavitation Phenomenon in an Oscillatory Oil Squeeze Film

2005 ◽  
Author(s):  
Wen Wang ◽  
Zhiming Zhang ◽  
Xiaoyang Chen ◽  
Meili Sun ◽  
D. C. Sun
Keyword(s):  
Dynamic Loading ◽  
Performance Model ◽  
Squeeze Film ◽  
External Excitation ◽  
Film Pressure ◽  
Film Performance ◽  
New Model ◽  
Oil Film ◽  
Cavitation Phenomenon ◽  
Oil Film Pressure

For the journal bearing under dynamic loading or under large external excitation condition, the oil film will not be a simple form as normal divided into continue oil film area and cavitation area. Because of squeeze effect, the boundary of oil film changes dynamically and oil film pressure shows more complex. As reviewed in [1], also there are some “cavitation algorithms” [2,3] developed, the oil film performance under dynamic loading remains unclear. For the research on nonlinear analysis of rotor-bearing system, one of the important work is to obtain oil film performance model under large external excitation. In order to investigate cavitation phenomenon, especially how cavitation changing and how much tensile stress oil films can support, a parallel-plate oscillatory squeeze film test-rig was built where a high-speed CCD was used to capture the development of cavitation, and synchronously the oil film pressure and the oscillatory displacement were measured [4]. A new cavitation model also was proposed [1]. In this paper, the new model will be validated with the experimental data. Some phenomenon also was investigated theoretically with new model.

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.

Simulation studies on static thermal behaviour of true elliptical and orthogonally displaced non-circular journal bearing

2016 ◽  
Vol 68 (3) ◽  
pp. 349-360 ◽  
Author(s):  
Amit Singla ◽  
Amit Chauhan
Keyword(s):  
Journal Bearing ◽  
Load Capacity ◽  
Current Trend ◽  
Operating Conditions ◽  
Performance Characteristics ◽  
Film Pressure ◽  
Content Type ◽  
Oil Film ◽  
Ellipticity Ratio ◽  
Oil Film Pressure

Purpose The current trend of modern industry is to use machineries which rotate at high speed along with the capability of carrying heavy rotor loads. This paper aims at static thermal analysis of two different profiles of non-circular journal bearings – a true elliptical bearing and orthogonal bearing. Design/methodology/approach The Reynolds equation has been solved through finite difference method to compute the oil film pressure. Parabolic temperature profile approximation technique has been used to solve the energy equation and thus used for computation of various bearing performance characteristics such as thermo-hydrodynamic oil film pressure, temperature, load capacity, Sommerfeld number and power loss characteristics across the bearing. The effect of ellipticity ratio on the bearing performance characteristics has also been obtained for both the elliptical and vertical offset bearing using three different commercially available grades of oil (Hydrol 32, 68 and 100). Findings It has been observed that the thermo-hydrodynamic pressure and temperature rise of the oil film is less in orthogonal bearing as compared to the true elliptical bearing for same operating conditions. The effect of ellipticity ratio of non-circularity on bearing performance parameters have been observed to be less in case of elliptical bearing as compared to orthogonal bearing. It has been concluded that though the rise in oil film temperature is high for true elliptical bearing, but still it should be preferred over orthogonal profile under study, as it has comparably good load-carrying capacity. Originality/value The performance parametric analysis will help the designers to select such kind of non-circular journal bearing for various applications.

scholarly journals Fuzzy Logic based Model to Predict Maximum Oil-Film Pressure in Journal Bearing

2013 ◽  
Vol 6 (20) ◽  
pp. 3871-3878 ◽  
Author(s):  
Diyar I. Ahmed ◽  
S. Kasolang ◽  
Basim A. Khidhir ◽  
B.F. Yousif
Keyword(s):  
Fuzzy Logic ◽  
Journal Bearing ◽  
Film Pressure ◽  
Oil Film ◽  
Oil Film Pressure

scholarly journals Coupled simulation of elastohydrodynamics and multi-flexible body dynamics in piston-lubrication system

2019 ◽  
Vol 11 (12) ◽  
pp. 168781401989585 ◽  
Author(s):  
Seongsu Kim ◽  
Juhwan Choi ◽  
Jin-Gyun Kim ◽  
Ryo Hatakeyama ◽  
Hiroshi Kuribara ◽  
...  
Keyword(s):  
Cylinder Block ◽  
Flexible Body ◽  
Asperity Contact ◽  
Lubrication System ◽  
Film Pressure ◽  
Oil Film ◽  
Piston Skirt ◽  
Body Dynamics ◽  
Flexible Body Dynamics ◽  
Oil Film Pressure

In this work, we propose a robust modeling and analysis technique of the piston-lubrication system considering fluid–structure interaction. The proposed schemes are based on combining the elastohydrodynamic analysis and multi-flexible body dynamics. In particular, multi-flexible body dynamics analysis can offer highly precise numerical results regarding nonlinear deformation of the piston skirt and cylinder bore, which can lead to more accurate results of film thickness for gaps filled with lubricant and of relative velocity of facing surfaces between the piston skirt and the cylinder block. These dynamic analysis results are also used in the elastohydrodynamic analysis to compute the oil film pressure and asperity contact pressure that are used as external forces to evaluate the dynamic motions of the flexible bodies. A series of processes are repeated to accurately predict the lubrication characteristics such as the clearance and oil film pressure. In addition, the Craig–Bampton modal reduction, which is a standard type of component mode synthesis, is employed to accelerate the computational speed. The performance of the proposed modeling schemes implemented in the RecurDyn™ multi-flexible body dynamics environment is demonstrated using a well-established numerical example, and the proposed simulation methods are also verified with the experimental results in a motor cycle engine (gasoline) which has a four cycle, single cylinder, overhead camshaft (OHC), air cooled.

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