On Liquid Film Pressure Sealing

1985 ◽  
Vol 107 (1) ◽  
pp. 67-72
Author(s):  
Jean-Nicolas Favre ◽  
I. L. Ryhming
Keyword(s):  
Thin Film ◽  
Surface Tension ◽  
Reynolds Number ◽  
Film Thickness ◽  
Liquid Film ◽  
The Other ◽  
Effective Pressure ◽  
Theoretical Predictions ◽  
Oil Injection ◽  
Inside Wall

The dynamics of the thin film established, by oil injection, on the inside wall of the casing in certain rotary compressors are analyzed both experimentally and theoretically. The film may provide an effective pressure seal to prevent leakage of air from one side of a rotor lobe to the other. It is found that Reynolds’ bearing theory, corrected for Reynolds number and surface tension effects, gives reasonable results for the film thickness needed to sustain typical operational pressure differences in the machine. The theoretical predictions have been verified experimentally in a series of tests performed in a specially designed apparatus.

Modelling of Partially Wetting Liquid Film Using an Enhanced Thin Film Model for Aero-Engine Bearing Chamber Applications

2020 ◽  
Author(s):  
K. Singh ◽  
M. Sharabi ◽  
R. Jefferson-Loveday ◽  
S. Ambrose ◽  
C. Eastwick ◽  
...  
Keyword(s):  
Thin Film ◽  
Contact Angle ◽  
Film Thickness ◽  
Liquid Film ◽  
Flow Rate ◽  
Operating Conditions ◽  
Film Model ◽  
Thin Film Model ◽  
Wide Range ◽  
Aero Engine

Abstract In the case of aero-engine, thin lubricating film servers dual purpose of lubrication and cooling. Prediction of dry patches or lubricant starved region in bearing or bearing chambers are required for safe operation of these components. In the present work thin liquid film flow is numerically investigated using the framework of the Eulerian thin film model (ETFM) for conditions which exhibit partial wetting phenomenon. This model includes a parameter that requires adjustment to account for the dynamic contact angle. Two different experimental data sets have been used for comparisons against simulations, which cover a wide range of operating conditions including varying the flow rate, inclination angle, contact angle, and liquid-gas surface tension coefficient. A new expression for the model parameter has been proposed and calibrated based on the simulated cases. This is employed to predict film thickness on a bearing chamber which is subjected to a complex multiphase flow. From this study, it is observed that the proposed approach shows good quantitative comparisons of the film thickness of flow down an inclined plate and for the representative bearing chamber. A comparison of model predictions with and without wetting and drying capabilities is also presented on the bearing chamber for shaft speed in the range of 2,500 RPM to 10,000 RPM and flow rate in the range of 0.5 liter per minute (LPM) to 2.5 LPM.

Bubble Entrapment in Sprayed Films

2014 ◽  
Author(s):  
A. Dalili ◽  
S. Chandra ◽  
J. Mostaghimi ◽  
H. T. Charles Fan ◽  
J. C. Simmer
Keyword(s):  
Surface Tension ◽  
Film Thickness ◽  
The Other ◽  
Bubble Motion ◽  
Sauter Mean Diameter ◽  
Glass Substrates ◽  
Buoyancy Forces ◽  
Mean Diameter ◽  
Imagej Software ◽  
Bubble Movement

A compressed air sprayer was used to spray model paint onto two glass substrates at the same time. Afterwards, one glass substrate was placed on a LED light source and still photographs were taken from the top using a DSLR camera with a timer system. The other substrate was put on a balance to record weight. Pictures and weight measurements were taken at 5 second intervals for 15 minutes. The sprayed film thickness was varied. The pictures were analyzed using ImageJ software. Bubble Count vs. Time, Sauter Mean Diameter (SMD) of Bubbles vs. Time as well as Weight vs. Time was plotted. It was seen that the pace of weight loss was faster for thinner films. The rate of bubble escape also depended on film thickness. It took a longer time for thicker films to lose the bubbles entrapped in them. In the first 30 seconds, large bubbles escaped due to buoyancy forces and afterwards surface-tension driven flows became dominant. There was also a lot of bubble movement in thicker films. The effect of gravity was studied as well. Gravity did not affect the bubble escape rate since a downward facing film had the same bubble count as an upward facing film confirming that bubble motion was not due to buoyancy forces alone. However, the SMD of bubbles in a downward facing film was larger than an upward facing film. Buoyancy is not a factor in bubble escape from the downward facing film and only surface-tension driven flows play a role.

Deformation characteristics of ultra-thin liquid film considering temperature and film thickness dependence of surface tension

2011 ◽  
Vol 17 (5-7) ◽  
pp. 983-990 ◽  
Author(s):  
Hiroshige Matsuoka ◽  
Koji Oka ◽  
Yusuke Yamashita ◽  
Fumihiro Saeki ◽  
Shigehisa Fukui
Keyword(s):  
Surface Tension ◽  
Film Thickness ◽  
Liquid Film ◽  
Thin Liquid Film ◽  
Thickness Dependence ◽  
Deformation Characteristics

Study on Breakdown Features and Characteristics of Film at the Corrugated Plate Corner

2020 ◽  
Author(s):  
Bo Wang ◽  
Bowen Chen ◽  
Bingzheng Ke ◽  
Ru Li ◽  
Gongqing Wang ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Film Thickness ◽  
Liquid Film ◽  
Relative Position ◽  
Water Film ◽  
Theoretical Formula ◽  
Film Rupture ◽  
Water Separation ◽  
Water Film Thickness ◽  
Film Breakdown

Abstract Corrugated plate dryer is a extremely vital equipment for steam-water separation in the fields of heat transfer and nuclear engineering. The corrugated plate is also a commonly used steam-water separator in steam generators in nuclear power plants. It is meaningful to study the breakdown characteristics and mechanism of the water film on corrugated plate wall. Water film thickness of steady flow is measured based on plane laser induced fluorescence (PLIF) technique and time series and its fitted equation of water film thickness are obtained, respectively. Besides, fluctuation characteristics of water film are analyzed by probability density function (PDF). Based on the dimensionless approach, the water film breakdown model at the corner of the corrugated plate is established. And the calculation equation of the relative position of the water film breakdown at the corner is deprived. The specific conclusions are as follows. The theoretical equation agrees well with the relative position of the water film breakdown at the corrugated plate corner. The evolution of the surface wave of water film is carried out in time and space. The PDF curve have no significant peak characteristics. Therefore, the spectrum has no characteristic frequency, that is, the water film has multi-frequency characteristics. Gravity of water film can be ignored in the water film model. The thickness sequences for falling film is measured and fitted. The two-dimensional model of water film breakdown at the corner is set up. The equation for the film thickness when the water film is just ruptured is obtained. Relative position of the water film rupture at the corner of the corrugated plate is theoretically related only to the structural parameters of the corrugated plate, the parameters of the gas phase and the liquid phase, and the Reynolds number of the liquid film. However, in the low Reynolds number region, the airflow velocity is extremely large, which causes certain fluctuations and nonlinear characteristics of the water film boundary position. Therefore, the theoretical formula is not particularly good at predicting the relative position of the breakdown in this region. I think that this nonlinear feature has obvious chaotic characteristics. The study of the chaotic characteristics generated by shearing the liquid film by high velocity flow airflow at the corner of the corrugated plate may become a prospect for future research.

scholarly journals On the origin of the circular hydraulic jump in a thin liquid film

2018 ◽  
Vol 851 ◽  
Author(s):  
Rajesh K. Bhagat ◽  
N. K. Jha ◽  
P. F. Linden ◽  
D. Ian Wilson
Keyword(s):  
Thin Film ◽  
Surface Tension ◽  
Liquid Film ◽  
Thin Liquid Film ◽  
Capillary Waves ◽  
Hydraulic Jumps ◽  
Planar Surface ◽  
Normal Impact ◽  
Viscous Forces

This study explores the formation of circular thin-film hydraulic jumps caused by the normal impact of a jet on an infinite planar surface. For more than a century, it has been believed that all hydraulic jumps are created due to gravity. However, we show that these thin-film hydraulic jumps result from energy loss due to surface tension and viscous forces alone. We show that, at the jump, surface tension and viscous forces balance the momentum in the liquid film and gravity plays no significant role. Experiments show no dependence on the orientation of the surface and a scaling relation balancing viscous forces and surface tension collapses the experimental data. A theoretical analysis shows that the downstream transport of surface energy is the previously neglected critical ingredient in these flows, and that capillary waves play the role of gravity waves in a traditional jump in demarcating the transition from the supercritical to subcritical flow associated with these jumps.

The Influence of Thin Film Thickness on the Characteristics of Bismuth Titanate Oxide

2007 ◽  
Vol 336-338 ◽  
pp. 129-132
Author(s):  
Cheng Fu Yang ◽  
Wei Kuo Chia ◽  
Ying Chung Chen ◽  
Chien Min Cheng
Keyword(s):  
Thin Film ◽  
Film Thickness ◽  
Room Temperature ◽  
Bismuth Titanate ◽  
Electrical Breakdown ◽  
Rf Magnetron Sputtering ◽  
The Other ◽  
Thin Film Thickness ◽  
Sims Analysis ◽  
Xrd Patterns

Bi4Ti3O12 thin films were deposited on Pt/Ti/Si(p-100) substrate by RF magnetron sputtering at room temperature, and crystallized in a RTA furnace at temperature of 675°C for 10 minutes. SIMS analysis identifies that bismuth content in the Bi4Ti3O12 thin film reduced slightly from the surface into a depth of approximately 200 nm. XRD patterns revealed (117) phase was dominated regardless the film thickness, and the intensity of the other peaks increased with the increase of film thickness. (200) peak became dominant when the thickness of films were greater than 680 nm. SEM observation showed that the grains were stripe plate-like, and the grain size increased with the increase of film thickness. Dielectric constant increased with the increase of film thickness, and kept around a certain value with the thickness ranging from 300 to 640 nm, then it rose again as the film thickness above 680 nm. The leakage current and electrical breakdown also strongly depended on the film thickness.

Further Experiments on the Sealing Mechanism of a Synthetic Rubber Lip Type Seal Operating on a Rotating Shaft

1973 ◽  
Vol 187 (1) ◽  
pp. 361-367 ◽  
Author(s):  
E. T. Jagger ◽  
D. Wallace
Keyword(s):  
Surface Tension ◽  
Film Thickness ◽  
Liquid Film ◽  
Hydrodynamic Lubrication ◽  
Contact Angles ◽  
Rotating Shaft ◽  
Synthetic Rubber ◽  
Sealing Mechanism ◽  
Inside Out ◽  
Lubrication Conditions

The paper shows that a seal of the type referred to operates under hydrodynamic lubrication conditions with a liquid film thickness of obout 0·5 μm. Contact angles of oil against rubber and steel are measured, and it is also shown by experiments with capillaries how a meniscus may be turned inside out to resist pressure. The conclusion is that the liquid film is prevented from leaking by the surface tension of the liquid itself.

Simultaneous measurement of dynamic force and spatial thin film thickness between deformable and solid surfaces by integrated thin liquid film force apparatus

Soft Matter ◽  
2016 ◽  
Vol 12 (44) ◽  
pp. 9105-9114 ◽  
Author(s):  
Xurui Zhang ◽  
Plamen Tchoukov ◽  
Rogerio Manica ◽  
Louxiang Wang ◽  
Qingxia Liu ◽  
...  
Keyword(s):  
Thin Film ◽  
Film Thickness ◽  
Liquid Film ◽  
Simultaneous Measurement ◽  
Thin Liquid Film ◽  
Solid Surfaces ◽  
Dynamic Force ◽  
Thin Film Thickness
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