A plastohydrodynamic inlet zone analysis for a visco-plastic lubricant

Wear ◽  
1978 ◽  
Vol 47 (1) ◽  
pp. 119-132 ◽  
Author(s):  
W.R.D. Wilson ◽  
B.B. Aggarwal
Keyword(s):  
Plastic Lubricant ◽  
Inlet Zone

Enhancement of nitrogen removal in subsurface flow constructed wetlands employing a 2-stage configuration, an unsaturated zone, and recirculation

1995 ◽  
Vol 32 (3) ◽  
pp. 59-67 ◽  
Author(s):  
Kevin D. White
Keyword(s):  
Constructed Wetlands ◽  
Nitrogen Removal ◽  
Constructed Wetland ◽  
Subsurface Flow ◽  
Great Promise ◽  
Effluent Recirculation ◽  
Wetland Treatment ◽  
Subsurface Flow Constructed Wetlands ◽  
Inlet Zone ◽  
Bod Removal

Constructed wetland technology is currently evolving into an acceptable, economically competitive alternative for many wastewater treatment applications. Although showing great promise for removing carbonaceous materials from wastewater, wetland systems have not been as successful at nitrification. This is primarily due to oxygen limitations. Nitrification does occur in conventional wetland treatment systems, but typically requires long hydraulic retention times. This paper describes a study that first evaluated the capability of subsurface flow constructed wetlands to treat a high strength seafood processor wastewater and then evaluated passive aeration configurations and effluent recirculation with respect to nitrogen treatment efficiency. The first stage of a 2-stage wetland treatment system exhibited a relatively short hydraulic retention time and was designed for BOD removal only. The second stage wetland employed an unsaturated inlet zone and effluent recirculation to enhance nitrification. Results indicate that organic loading, and thus BOD removal, in the first stage wetland is key to optimal nitrification. Passive aeration through an unsaturated inlet zone and recirculation achieved up to 65-70 per cent ammonia nitrogen removal at hydraulic retention times of about 3.5 days. Inlet zone configuration and effluent recirculation is shown to enhance the nitrogen removal capability of constructed wetland treatment systems.

Use of artificial wetland for the treatment of surface and wastewater

1996 ◽  
Vol 33 (4-5) ◽  
pp. 309-313
Author(s):  
Jan Šálek ◽  
František Marcián ◽  
Iman Elazizy
Keyword(s):  
Water Level ◽  
Root Zone ◽  
Artificial Wetland ◽  
Root Zones ◽  
Different Types ◽  
Water Media ◽  
Inlet Zone

Vegetative root zone methods are based on self-purifying processes that take place in the soil, wetland and vegetation containing water media. Our studies are concentrated on the course of puryfying in relation with the length of the filtration bed and on the progress of eliminating the ammoniacal pollution. The research proved that the essential part of the puryfying process takes place within the inlet zone (Figs 1 and 2). The decomposition of ammonia proceeds very slowly. The process of nitrification is affected by the lack of oxygen in the filtration media. To improve the effectiveness of vegetative root zone methods we suggest specific steps: an adjustment of the inlet zone, a system of cascades, a water level pulsation system and combinations of different types and arrangements of vegetative root zones.

Recent Patents on Abnormal Hydrodynamic Thrust Slider Bearings: Part II-the Second Mode of the Bearings

2020 ◽  
Vol 13 (1) ◽  
pp. 35-40
Author(s):  
Yongbin Zhang ◽  
Huansheng Cheng ◽  
Junyan Wang
Keyword(s):  
Operating Conditions ◽  
Moving Surface ◽  
Friction Coefficients ◽  
Surface Separation ◽  
Slider Bearings ◽  
Stationary Surface ◽  
Boundary Slippage ◽  
Load Carrying ◽  
Second Mode ◽  
Inlet Zone

Background: As a successive part, the paper introduces the second mode of abnormal hydrodynamic thrust slider bearings with divergent surface separations registered in the patents, where the boundary slippage is artificially designed both on the stationary surface in the inlet zone and on the whole moving surface. Objective : To introduce a second method for artificially designing the boundary slippage for the formation of abnormal hydrodynamic thrust slider bearings. Methods: The analytical results are presented for the introduced bearings. The performances of the bearings are demonstrated. Result: : In appropriate operating conditions, the introduced bearings can have considerable loadcarrying capacities with low friction coefficients on the scales 10-3 or 10-4. With the weakening of the boundary slippage on the moving surface, the load-carrying capacities of the bearings are all increased, while the friction coefficients of the bearings are all reduced. Conclusion: When the boundary slippage is present both on the stationary surface in the bearing inlet zone and on the whole moving surface, abnormal hydrodynamic thrust slider bearings can be designed with the surface separation in the bearing inlet zone lower than that in the bearing outlet zone. The performances of these bearings are quite satisfactory.

Scale Effects in Generalized Newtonian Elastohydrodynamic Films

2008 ◽  
Author(s):  
I. I. Kudish ◽  
P. Kumar ◽  
M. M. Khonsary ◽  
S. Bair
Keyword(s):  
Film Thickness ◽  
Scale Effects ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Viscosity Coefficient ◽  
Shear Thinning ◽  
Effective Pressure ◽  
Practical Advantage ◽  
Inlet Zone ◽  
Real Machine

The prediction of elastohydrodynamic lubrication (EHL) film thickness requires knowledge of the lubricant properties. Today, in many instances, the properties have been obtained from a measurement of the central film thickness in an optical EHL point contact simulator and the assumption of a classical Newtonian film thickness formula. This technique has the practical advantage of using an effective pressure-viscosity coefficient which compensates for shear-thinning. We have shown by a perturbation analysis and by a full EHL numerical solution that the practice of extrapolating from a laboratory scale measurement of film thickness to the film thickness of an operating contact within a real machine may substantially overestimate the film thickness in the real machine if the machine scale is smaller and the lubricant is shear-thinning in the inlet zone.

Mixed Lubrication Model for Cold Rolling Considering the Inlet and Deformation Zones

2012 ◽  
Author(s):  
Martin Bergmann ◽  
Klaus Zeman ◽  
Alexander Kainz ◽  
Konrad Krimpelstätter ◽  
Dieter Paesold ◽  
...  
Keyword(s):  
Cold Rolling ◽  
Film Formation ◽  
Mixed Lubrication ◽  
Bulk Deformation ◽  
Metallic Surfaces ◽  
Hydrodynamic Friction ◽  
Plastic Strip ◽  
Coupled Equations ◽  
Inlet Zone ◽  
Raphson Method

A mixed lubrication model for cold rolling was developed by separating, according to common concepts, the domain of calculation into two zones: the inlet zone and the zone of plastic strip bulk deformation. The analysis of the inlet zone mainly focuses on film formation from different lubricants based on the evolution of layers consisting of neat oil on the metallic surfaces. In the zone of plastic strip bulk deformation, contributions of boundary and hydrodynamic friction are modeled incorporating longitudinal and transversal roughness components. Lubricant pressure, which is influenced by the geometry of these roughness structures, is governed by hydrodynamic mechanisms. Additionally, lubricant temperature in the roll bite is predicted by an integrated thermodynamics sub-model. While coupling between the inlet and plastic deformation zones is performed iteratively, the highly non-linear and coupled equations for the latter zone are solved simultaneously by applying a variant of the well-known damped Newton-Raphson method.

Observations of Liquid Droplet Behavior and Oil Film Formation in O/W Type Emulsion Lubrication

1988 ◽  
Vol 110 (2) ◽  
pp. 348-353 ◽  
Author(s):  
T. Nakahara ◽  
T. Makino ◽  
K. Kyogoku
Keyword(s):  
High Speed ◽  
Liquid Droplet ◽  
Film Formation ◽  
Flat Glass ◽  
Glass Plate ◽  
Rolling Speed ◽  
Liquid Droplets ◽  
Speed Range ◽  
Oil Concentration ◽  
Inlet Zone

The behavior of liquid droplets in O/W type emulsions flowing between a flat glass plate and a metal roller was observed by means of a microscope. The behavior of the droplets introduced into the EHL film was found to be related to the streamlines of the continuous water phase in the vicinity of the inlet zone. It was observed that the oil droplets which penetrated into the EHL zone formed an oily pool (an oily film zone) containing water droplets in the inlet zone close to the EHL zone. This oily pool was a W/O emulsion rich in oil caused by phase inversion. The effects of oil concentration, emulsifier content and rolling speed on the area of the oily pool were investigated, and it was found that the extent of the oily pool was influenced by the rolling speed as well as oil concentration. The EHD film thickness was measured by means of optical interferometry with use of two wavelengths, and the measured results were compared with the calculated ones employing the starvation theory of Wolveridge et al. and the empirical equation of Wymer and Cameron for the region of the oil pool. It was found that course droplets play an important role in film formation by causing the formation of the oily pool in the low speed range. In the high speed range, however, a fine O/W emulsion forms the film.

Reduction of Air Films in Magnetic Recording by External Air Pressure

1974 ◽  
Vol 96 (2) ◽  
pp. 247-249 ◽  
Author(s):  
A. Eshel
Keyword(s):  
Film Thickness ◽  
Magnetic Recording ◽  
Substantial Reduction ◽  
External Pressure ◽  
Numerical Results ◽  
Air Pressure ◽  
Foil Bearings ◽  
Inlet Zone

The effect of external pressure exerted on foil bearings is studied. Analysis and numerical results are provided for its influence on the bearing gap. It is shown that a substantial reduction in film thickness can be achieved by applying small pressures in the inlet zone. The effect of several pertinent parameters is presented and discussed.

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