Analysis of Nanoparticle Additive Couple Stress Fluids in Three-layered Journal Bearing

International Nuclear Information System (INIS)

Rao, T V V L N; Sufian, S; Mohamed, N M

2013-01-01

The present theoretical study investigates the load capacity and friction coefficient in a three-layered journal bearing lubricated with nanoparticle additive couple stress fluids. The couple stresses effects are analyzed based on Stokes micro-continuum theory. The nondimensional pressure and shear stress expressions are derived using modified Reynolds equation. The nondimensional load capacity increases and the coefficient of friction decreases using nanoparticle additive lubricants with couple stress effects. The three-layered journal bearing performance characteristics are improved with increase in both (i) surface adsorbent fluid film layer thickness and (ii) dynamic viscosity ratio of surface to core layer.

Self lubricating fluid bearings

International Nuclear Information System (INIS)

Kapich, D.D.

1980-01-01

The invention concerns self lubricating fluid bearings, which are used in a shaft sealed system extending two regions. These regions contain fluids, which have to be isolated. A first seal is fluid tight for the first region between the carter shaft and the shaft. The second seal is fluid tight between the carter and the shaft, it communicates with the second region. The first fluid region is the environment surrounding the shaft carter. The second fluid region is a part of a nuclear reactor which contains the cooling fluid. The shaft is conceived to drive a reactor circulating and cooling fluid [fr

Hydrodynamic bearing lubricated with magnetic fluids

International Nuclear Information System (INIS)

Urreta, H; Leicht, Z; Sanchez, A; Agirre, A; Kuzhir, P; Magnac, G

2009-01-01

This paper summarizes the work carried out in the development of hydrodynamic lubricated journal bearings with magnetic fluids. Two different fluids have been analyzed, one ferrofluid from FERROTEC APG s10n and one magnetorheological fluid from LORD Corp., MRF122-2ED. Theoretical analysis has been carried out with numerical solutions of Reynolds equation, based on apparent viscosity modulation for ferrofluid and Bingham model for MR fluid. To validate this model, one test bench has been designed, manufactured and set up, where preliminary results shown in this paper demonstrate that magnetic fluids can be used to develop active journal bearings.

A Study Of Magnetic Fluid Based Squeeze Film Between Porous ...

African Journals Online (AJOL)

Efforts have been made to study and analyze the effect of surface roughness on the performance of magnetic fluid based squeeze film between porous elliptic plates. The transverse roughness of the bearing surface is characterized by a stochastic random variable with non-zero mean, variance and skewness.

Trends in Controllable Oil Film Bearings

DEFF Research Database (Denmark)

Santos, Ilmar

2011-01-01

This work gives an overview about the theoretical and experimental achievements of mechatronics applied to oil film bearings, with the aim of: controlling the lateral vibration of flexible rotating shafts; modifying bearing dynamic characteristics, as stiffness and damping properties; increasing......" components and be applied to rotating machines with the goal of avoiding unexpected stops of plants, performing rotordynamic tests and identifying model parameters "on site". Emphasis is given to the controllable lubrication (active lubrication) applied to different types of oil film bearings, i...

Self-lubricating fluid bearing assembly

International Nuclear Information System (INIS)

Kapich, D.D.

1981-01-01

A sealed self-lubricating fluid bearing assembly is described for circulating fluid in the form of a gas coolant in a nuclear reactor, the power for the circulator being provided by a shaft located within the primary containment vessel. In such a system the reactor coolant is isolated from the fluid region at the far end of the drive shaft. (U.K.)

Squeeze-film flow between a flat impermeable bearing and an anisotropic porous bed

Science.gov (United States)

Karmakar, Timir; Raja Sekhar, G. P.

2018-04-01

We consider a theoretical model of the squeeze film in the presence of a porous bed. The gap between the porous bed and the bearing is assumed to be filled with a Newtonian fluid. We use the Navier-Stokes equation in the fluid region and the Darcy equation in the fluid filled porous region. Lubrication approximation is used to derive the corresponding evolution equation for the film thickness. We use G. S. Beavers and D. D. Joseph ["Boundary conditions at a naturally permeable wall," J. Fluid. Mech. 30, 197-207 (1967)] and M. Le Bars and M. G. Worster ["Interfacial conditions between a pure fluid and a porous medium: Implications for binary alloy solidification," J. Fluid. Mech. 550, 149-173 (2006)] condition at the liquid porous interface and present a detailed analysis on the corresponding impact. We assume that the porous bed is anisotropic in nature with permeabilities K2 and K1 along the principal axes. Accordingly, the anisotropic angle ϕ is taken as the angle between the horizontal direction and principal axis with permeability K2. We show that the anisotropic permeability ratio and the anisotropic angle make a significant influence on the contact time, flux, velocity, etc. Contact time to meet the porous bed when a bearing approaches under a constant prescribed load is estimated. We present some important findings (relevant to the knee joint) based on the anisotropic properties of the human cartilage. For a prescribed constant load, we have estimated the time duration, during which a healthy human knee remains fluid lubricated.

Analysis of HD Journal Bearings Considering Elastic Deformation and Non-Newtonian Rabinowitsch Fluid Model

Directory of Open Access Journals (Sweden)

J. Javorova

2016-06-01

Full Text Available The purpose of this paper is to study the performance of a finite length journal bearing, taking into account effects of non-Newtonian Rabinowitsch flow rheology and elastic deformations of the bearing liner. According to the Rabinowitsch fluid model, the cubic-stress constitutive equation is used to account for the non-Newtonian effects of pseudoplastic and dilatant lubricants. Integrating the continuity equation across the film, the nonlinear non-Newtonian Reynolds-type equation is derived. The elasticity part of the problem is solved on the base of Vlassov model of an elastic foundation. The numerical solution of the modified Reynolds equation is carried out by using FDM with over-relaxation technique. The results for steady state bearing performance characteristics have been calculated for various values of nonlinear factor and elasticity parameters. It was concluded that in comparison with the Newtonian lubricants, higher values of film pressure and load carrying capacity have been obtained for dilatant lubricants, while the case was reversed for pseudoplastic lubricants.

Feasibility of Applying Controllable Lubrication to Dynamically Loaded Journal Bearings

DEFF Research Database (Denmark)

Estupinan, Edgar Alberto; Santos, Ilmar

2009-01-01

A multibody dynamic model of the main mechanical components of a hermetic reciprocating compressor is presented in this work. Considering that some of the mechanical elements are interconnected via thin fluid films, the multibody dynamic model is coupled to the equations from the dynamics...... of the fluid films, based on fluid film theory. For a dynamically loaded journal bearing, the fluid film pressure distribution can be computed by numerically solving the Reynolds equation, by means of finite-difference method. Particularly, in this study the main focus is on the lubrication behavior...... and reaction forces in a reciprocating compressor have a cyclic behavior, periodic oil pressure injection rules based on the instantaneous crank angle and load bearing condition can be established. In this paper, several bearing configurations working under different oil pressure injection rules conditions...

Modal interaction and vibration suppression in industrial turbines using adjustable journal bearings

Science.gov (United States)

Chasalevris, Athanasios; Dohnal, Fadi

2016-09-01

The vibration suppression by deliberately introducing a parametric excitation in the fluid-film bearings is investigated for an industrial turbine rotor system. A journal bearing with variable adjustable geometry is operated in such a way that the effective stiffness and damping properties vary periodically in time. The proposed bearing is designed for having the ability of changing the bearing fluid film thickness in a semi-active manner. Such an adjustment of the journal bearing properties introduces in the system a time-periodic variation of the effective stiffness and damping properties of the fluid-film. If the time-periodicity is tuned properly to match a parametric anti-resonance, vibration suppression is achieved in the overall system. The paper presents the principle of operation of the recently developed bearings. The simulation of an industrial turbine rotor-bearing shaft line at induced parametric excitation motivates the further development and application of such bearings since the vibration amplitudes are considerably decreased in critical speeds.

Scaling laws for radial foil bearings

Science.gov (United States)

Honavara Prasad, Srikanth

The effects of fluid pressurization, structural deformation of the compliant members and heat generation in foil bearings make the design and analysis of foil bearings very complicated. The complex fluid-structural-thermal interactions in foil bearings also make modeling efforts challenging because these phenomena are governed by highly non-linear partial differential equations. Consequently, comparison of various bearing designs require detailed calculation of the flow fields (velocities, pressures), bump deflections (structural compliance) and heat transfer phenomena (viscous dissipation in the fluid, frictional heating, temperature profile etc.,) resulting in extensive computational effort (time/hardware). To obviate rigorous computations and aid in feasibility assessments of foil bearings of various sizes, NASA developed the "rule of thumb" design guidelines for estimation of journal bearing load capacity. The guidelines are based on extensive experimental data. The goal of the current work is the development of scaling laws for radial foil bearings to establish an analytical "rule of thumb" for bearing clearance and bump stiffness. The use of scale invariant Reynolds equation and experimentally observed NASA "rule of thumb" yield scale factors which can be deduced from first principles. Power-law relationships between: a. Bearing clearance and bearing radius, and b. bump stiffness and bearing radius, are obtained. The clearance and bump stiffness values obtained from scaling laws are used as inputs for Orbit simulation to study various cases. As the clearance of the bearing reaches the dimensions of the material surface roughness, asperity contact breaks the fluid film which results in wear. Similarly, as the rotor diameter increases (requiring larger bearing diameters), the load capacity of the fluid film should increase to prevent dry rubbing. This imposes limits on the size of the rotor diameter and consequently bearing diameter. Therefore, this thesis aims

Nonlinear Dynamical Analysis for a Plain Bearing

Directory of Open Access Journals (Sweden)

Ali Belhamra

2014-03-01

Full Text Available This paper investigates the nonlinear dynamic behavior for a plain classic bearing (fluid bearing lubricated by a non-Newtonian fluid of a turbo machine rotating with high speed; this type of fluid contains additives viscosity (couple-stress fluid film. The solution of the nonlinear dynamic problem of this type of bearing is determined with a spatial discretisation of the modified Reynolds' equation written in dynamic mode by using the optimized short bearing theory and a temporal discretisation for equations of rotor motion by the help of Euler's explicit diagram. This study analyzes the dynamic behavior of a rotor supported by two couple-stress fluid film journal lubricant enhances the dynamic stability of the rotor-bearing system considerably compared to that obtained when using a traditional Newtonian lubricant. The analysis shows that the dynamic behavior of a shaft which turns with high velocities is strongly nonlinear even for poor eccentricities of unbalance; the presence of parameters of couple stress allows strongly attenuating the will synchrony (unbalance and asynchrony (whipping amplitudes of vibrations of the shaft which supports more severe conditions (large unbalances.

Experimental Performance Study of a High Speed Oil Lubricated Polymer Thrust Bearing

Directory of Open Access Journals (Sweden)

Jie Zhou

2015-01-01

Full Text Available With the demand for turbomachinery to operate at higher speeds, loads, and power, fluid film bearings that support turbomachinery must be capable of operating in these more demanding applications. Thrust bearings operating at high speeds and loads can experience high surface temperatures and thin fluid film thickness. Typically, babbitt (white metal is the bearing lining material for most turbomachinery bearings but is limited in operating temperature and allowable film thickness. Polymer based materials are alternative materials that can operate at high temperatures and with thin films and have been in use for many decades in high load applications, such as electric submersible pumps (ESP. Test results of polymer lined thrust bearings subjected to modern turbomachinery speeds and loads are presented and compared to babbitt lined bearings of the same design and under similar conditions. The test results show polymer lined thrust bearings can operate at higher bearing unit loads than babbitt.

Evaluation of effect of oil film of rotor bearing

Science.gov (United States)

Alekseeva, L. B.; Maksarov, V. V.

2018-03-01

The high-rpm rotors were subjected to the dynamic analysis. Oscillations of a rotor spinning in gapped bearings were considered. It was stated that the rotor necks motion pattern depends on a lot of factors: a ratio of static and dynamic loads on the bearing, radial clearance size, presence of oil film between a neck and a bearing, elastic and inertial properties of a mounting group. The most unfavourable mode where static and dynamic loads are equal was detected without taking into account the oil film impact. The impact of oil film on the bearing assembly dynamics is significant in high-rpm rotors. The presence of oil film can possibly cause rotor buckling failure and self-starting. Rotor motion stability in small was studied. Herewith, various schemes were considered. Expressions, determining the stability zones of a rigid rotor on the fixed support and the supports with elastic and inertial elements, were given.

Actively lubricated bearings applied as calibrated shakers to aid parameter identification in rotordynamics

DEFF Research Database (Denmark)

Santos, Ilmar; Cerda Varela, Alejandro Javier

2013-01-01

The servo valve input signal and the radial injection pressure are the two main parameters responsible for dynamically modifying the journal oil film pressure and generating active fluid film forces in controllable fluid film bearings. Such fluid film forces, resulting from a strong coupling...... domain and the application of such a controllable bearing as a calibrated shaker aiming at determining the frequency response function (FRF) of rotordynamic systems; b) experimental quantification of the influence of the supply pressure and servo valve input signal on the FRF of rotor-journal bearing...... between hydrodynamic, hydrostatic and controllable lubrication regimes, can be used either to control or to excite rotor lateral vibrations. An accurate characterization of the active oil film forces is of fundamental importance to elucidate the feasibility of applying the active lubrication as non...

Journal and Wave Bearing Impedance Calculation Software

Science.gov (United States)

Hanford, Amanda; Campbell, Robert

2012-01-01

The wave bearing software suite is a MALTA application that computes bearing properties for user-specified wave bearing conditions, as well as plain journal bearings. Wave bearings are fluid film journal bearings with multi-lobed wave patterns around the circumference of the bearing surface. In this software suite, the dynamic coefficients are outputted in a way for easy implementation in a finite element model used in rotor dynamics analysis. The software has a graphical user interface (GUI) for inputting bearing geometry parameters, and uses MATLAB s structure interface for ease of interpreting data. This innovation was developed to provide the stiffness and damping components of wave bearing impedances. The computational method for computing bearing coefficients was originally designed for plain journal bearings and tilting pad bearings. Modifications to include a wave bearing profile consisted of changing the film thickness profile given by an equation, and writing an algorithm to locate the integration limits for each fluid region. Careful consideration was needed to implement the correct integration limits while computing the dynamic coefficients, depending on the form of the input/output variables specified in the algorithm.

Three Types of Active Lubrication Systems for the Main Bearings of Reciprocating Machines

DEFF Research Database (Denmark)

Santos, Ilmar; Pulido, E. E.

2010-01-01

method (flexible components). The main equations that govern the dynamics of the injection for a hydraulic-actuated, a piezoelectric-actuated and a mechanical-actuated oil injector are presented in this study. The global system is numerically solved using as a case of study a single-cylinder combustion......In the paper the authors investigate three different schemes for the realization of the controllable oil injection system to be couple to the main engine bearings. The use of active lubrication in fluid film bearings helps to enhance the hydrodynamic fluid film by increasing the fluid film...

Coupling analysis of frictional heat of fluid film and thermal deformation of mechanical seal end faces

International Nuclear Information System (INIS)

Zhou Jianfeng; Gu Boqin

2007-01-01

The heat transfer model of the rotating ring and the stationary ring of mechanical seal was built. The method to calculate the frictional heat that transferred by the rings was given. the coupling analysis of the frictional heat of fluid film and thermal deformation of end faces was carried out by using FEA and BP ANN, and the relationship among the rotational speed ω, the fluid film thickness h i on the inner diameter of sealing face and the radial separation angle β of deformed end faces was obtained. Corresponding to a given ω, h i and β can be obtained by the equilibrium condition between the closing force and the bearing force of fluid film. The relationship between the leakage rate and the closing force was analyzed, and the fundamental of controlling the leakage rate by regulating the closing force was also discussed. (authors)

Study the Dynamic Behavior of Rotor Supported on a Worn Journal Bearings

Directory of Open Access Journals (Sweden)

Adnan Naji Jamil

2015-12-01

Full Text Available In this paper, the effect of wear in the fluid film journal bearings on the dynamic behavior of rotor bearing system has been studied depending on the analytical driven of dynamic stiffness and damping coefficients of worn journal bearing. The finite element method was used to modeling rotor bearing system. The unbalance response, critical speed and natural frequency of rotor bearing system have been studied to determine the changes in these parameters due to wear. MATLAB software was used to find the analytical values of dynamic coefficients of journal bearing. The results of rotor mounted on fluid film journal bearings showed that the wear in journal bearing increases the amplitude of unbalance response and decrease critical speed, stability and the natural frequencies.

Effect of Temperature and Electric Field on the Damping and Stiffness Characteristics of ER Fluid Short Squeeze Film Dampers

Directory of Open Access Journals (Sweden)

H. P. Jagadish

2013-01-01

Full Text Available Squeeze film dampers are novel rotor dynamic devices used to alleviate small amplitude, large force vibrations and are used in conjunction with antifriction bearings in aircraft jet engine bearings to provide external damping as these possess very little inherent damping. Electrorheological (ER fluids are controllable fluids in which the rheological properties of the fluid, particularly viscosity, can be controlled in accordance with the requirements of the rotor dynamic system by controlling the intensity of the applied electric field and this property can be utilized in squeeze film dampers, to provide variable stiffness and damping at a particular excitation frequency. The paper investigates the effect of temperature and electric field on the apparent viscosity and dynamic (stiffness and damping characteristics of ER fluid (suspension of diatomite in transformer oil using the available literature. These characteristics increase with the field as the viscosity increases with the field. However, these characteristics decrease with increase in temperature and shear strain rate as the viscosity of the fluid decreases with temperature and shear strain rate. The temperature is an important parameter as the aircraft jet engine rotors are located in a zone of high temperature gradients and the damper fluid is susceptible to large variations in temperature.

Numerical analysis of capillary compensated micropolar fluid lubricated hole-entry journal bearings

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Nathi Ram

2016-06-01

Full Text Available The micropolar lubricated symmetric/asymmetric hole-entry bearings using capillary restrictor have been analyzed in the present work. Reynolds equation for micropolar lubricant has been derived and solved by FEM. The results have been computed using selected parameters of micropolar lubricant for hole-entry hydrostatic/hybrid journal bearings. A significant increase in damping and stiffness coefficients is observed for bearings having micropolar parameter N2=0.9, lm=10 than similar bearings under Newtonian lubricant. The threshold speed gets increased when symmetric bearing lubricated under micropolar fluid than Newtonian lubricant. The threshold speed gets increased when symmetric bearing lubricated under micropolar fluid than Newtonian lubricant.

Laminar motion of the incompressible fluids in self-acting thrust bearings with spiral grooves.

Science.gov (United States)

Velescu, Cornel; Popa, Nicolae Calin

2014-01-01

We analyze the laminar motion of incompressible fluids in self-acting thrust bearings with spiral grooves with inner or external pumping. The purpose of the study is to find some mathematical relations useful to approach the theoretical functionality of these bearings having magnetic controllable fluids as incompressible fluids, in the presence of a controllable magnetic field. This theoretical study approaches the permanent motion regime. To validate the theoretical results, we compare them to some experimental results presented in previous papers. The laminar motion of incompressible fluids in bearings is described by the fundamental equations of fluid dynamics. We developed and particularized these equations by taking into consideration the geometrical and functional characteristics of these hydrodynamic bearings. Through the integration of the differential equation, we determined the pressure and speed distributions in bearings with length in the "pumping" direction. These pressure and speed distributions offer important information, both quantitative (concerning the bearing performances) and qualitative (evidence of the viscous-inertial effects, the fluid compressibility, etc.), for the laminar and permanent motion regime.

Laminar Motion of the Incompressible Fluids in Self-Acting Thrust Bearings with Spiral Grooves

Directory of Open Access Journals (Sweden)

Cornel Velescu

2014-01-01

Full Text Available We analyze the laminar motion of incompressible fluids in self-acting thrust bearings with spiral grooves with inner or external pumping. The purpose of the study is to find some mathematical relations useful to approach the theoretical functionality of these bearings having magnetic controllable fluids as incompressible fluids, in the presence of a controllable magnetic field. This theoretical study approaches the permanent motion regime. To validate the theoretical results, we compare them to some experimental results presented in previous papers. The laminar motion of incompressible fluids in bearings is described by the fundamental equations of fluid dynamics. We developed and particularized these equations by taking into consideration the geometrical and functional characteristics of these hydrodynamic bearings. Through the integration of the differential equation, we determined the pressure and speed distributions in bearings with length in the “pumping” direction. These pressure and speed distributions offer important information, both quantitative (concerning the bearing performances and qualitative (evidence of the viscous-inertial effects, the fluid compressibility, etc., for the laminar and permanent motion regime.

Use of high-temperature superconducting films in superconducting bearings

International Nuclear Information System (INIS)

Cansiz, A.

1999-01-01

We have investigated the effect of high-temperature superconductor (HTS) films deposited on substrates that are placed above bulk HTSs in an attempt to reduce rotational drag in superconducting bearings composed of a permanent magnet levitated above the film/bulk HTS combination. According to the critical state model, hysteresis energy loss is inversely proportional to critical current density, J c , and because HTS films typically have much higher J c than that of bulk HTS, the film/bulk combination was expected to reduce rotational losses by at least one order of magnitude in the coefficient of fiction, which in turn is a measure of the hysteresis losses. We measured rotational losses of a superconducting bearing in a vacuum chamber and compared the losses with and without a film present. The experimental results showed that contrary to expectation, the rotational losses are increased by the film. These results are discussed in terms of flux drag through the film, as well as of the critical state model

Bulk-Flow Analysis of Hybrid Thrust Bearings for Advanced Cryogenic Turbopumps

Science.gov (United States)

SanAndres, Luis

1998-01-01

A bulk-flow analysis and computer program for prediction of the static load performance and dynamic force coefficients of angled injection, orifice-compensated hydrostatic/hydrodynamic thrust bearings have been completed. The product of the research is an efficient computational tool for the design of high-speed thrust bearings for cryogenic fluid turbopumps. The study addresses the needs of a growing technology that requires of reliable fluid film bearings to provide the maximum operating life with optimum controllable rotordynamic characteristics at the lowest cost. The motion of a cryogenic fluid on the thin film lands of a thrust bearing is governed by a set of bulk-flow mass and momentum conservation and energy transport equations. Mass flow conservation and a simple model for momentum transport within the hydrostatic bearing recesses are also accounted for. The bulk-flow model includes flow turbulence with fluid inertia advection, Coriolis and centrifugal acceleration effects on the bearing recesses and film lands. The cryogenic fluid properties are obtained from realistic thermophysical equations of state. Turbulent bulk-flow shear parameters are based on Hirs' model with Moody's friction factor equations allowing a simple simulation for machined bearing surface roughness. A perturbation analysis leads to zeroth-order nonlinear equations governing the fluid flow for the thrust bearing operating at a static equilibrium position, and first-order linear equations describing the perturbed fluid flow for small amplitude shaft motions in the axial direction. Numerical solution to the zeroth-order flow field equations renders the bearing flow rate, thrust load, drag torque and power dissipation. Solution to the first-order equations determines the axial stiffness, damping and inertia force coefficients. The computational method uses well established algorithms and generic subprograms available from prior developments. The Fortran9O computer program hydrothrust runs

Noise estimation of oil lubricated journal bearings

International Nuclear Information System (INIS)

Rho, Byoung Hoo; Kim, Kyung Woong

2003-01-01

Noise estimating procedures of oil lubricated journal bearings are presented. Nonlinear analysis of rotor-bearing system including unbalance mass of the rotor is performed in order to obtain acoustical properties of the bearing. Acoustical properties of the bearing are investigated through frequency analysis of the pressure fluctuation of the fluid film calculated from the nonlinear analysis. Noise estimating procedures presented in this paper could aid in the evaluation and understanding of acoustical properties of oil lubricated journal bearings

A journal bearing with variable geometry for the suppression of vibrations in rotating shafts: Simulation, design, construction and experiment

Science.gov (United States)

Chasalevris, Athanasios; Dohnal, Fadi

2015-02-01

The idea for a journal bearing with variable geometry was formerly developed and investigated on its principles of operation giving very optimistic theoretical results for the vibration quenching of simple and more complicated rotor bearing systems during the passage through the first critical speed. The journal bearing with variable geometry is presented in this paper in its final form with the detailed design procedure. The current journal bearing was constructed in order to be applied in a simple real rotor bearing system that already exists as an experimental facility. The current paper presents details on the manufactured prototype bearing as an experimental continuation of previous works that presented the simulation of the operating principle of this journal bearing. The design parameters are discussed thoroughly under the numerical simulation for the fluid film pressure in dependency of the variable fluid film thickness during the operation conditions. The implementation of the variable geometry bearing in an experimental rotor bearing system is outlined. Various measurements highlight the efficiency of the proposed bearing element in vibration quenching during the passage through resonance. The inspiration for the current idea is based on the fact that the alteration of the fluid film characteristics of stiffness and damping during the passage through resonance results in vibration quenching. This alteration of the bearing characteristics is achieved by the introduction of an additional fluid film thickness using the passive displacement of the lower half-bearing part. • The contribution of the current journal bearing in vibration quenching. • Experimental evidence for the VGJB contribution.

Nonlinear Dynamic Response of an Unbalanced Flexible Rotor Supported by Elastic Bearings Lubricated with Piezo-Viscous Polar Fluids

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Mustapha Lahmar

2015-04-01

Full Text Available On the basis of the V. K. Stokes micro-continuum theory, the effects of couple stresses on the nonlinear dynamic response of the unbalanced Jeffcott’s flexible rotor supported by layered hydrodynamic journal bearings is presented in this paper. A nonlinear transient modified Reynolds’ equation is derived and discretized by the finite element method to obtain the fluid-film pressure field as well as the film thickness by means of the implicit Euler method. The nonlinear orbits of the rotor center are determined by solving the nonlinear differential equations of motion with the explicit Euler’s scheme taking into account the flexibility of rotor. According to the obtained results, the combined effects of couple stresses due to the presence of polymer additives in lubricant and the pressure dependent viscosity on the nonlinear dynamic response of the rotor-bearing system are significant and cannot be ignored or overlooked. As expected, these effects are more noticeable for polymers characterized by higher length molecular chains.

Vibration Propagation of Gear Dynamics in a Gear-Bearing-Housing System Using Mathematical Modeling and Finite Element Analysis

Science.gov (United States)

Parker, Robert G.; Guo, Yi; Eritenel, Tugan; Ericson, Tristan M.

2012-01-01

Vibration and noise caused by gear dynamics at the meshing teeth propagate through power transmission components to the surrounding environment. This study is devoted to developing computational tools to investigate the vibro-acoustic propagation of gear dynamics through a gearbox using different bearings. Detailed finite element/contact mechanics and boundary element models of the gear/bearing/housing system are established to compute the system vibration and noise propagation. Both vibration and acoustic models are validated by experiments including the vibration modal testing and sound field measurements. The effectiveness of each bearing type to disrupt vibration propagation is speed-dependent. Housing plays an important role in noise radiation .It, however, has limited effects on gear dynamics. Bearings are critical components in drivetrains. Accurate modeling of rolling element bearings is essential to assess vibration and noise of drivetrain systems. This study also seeks to fully describe the vibro-acoustic propagation of gear dynamics through a power-transmission system using rolling element and fluid film wave bearings. Fluid film wave bearings, which have higher damping than rolling element bearings, could offer an energy dissipation mechanism that reduces the gearbox noise. The effectiveness of each bearing type to disrupt vibration propagation in explored using multi-body computational models. These models include gears, shafts, rolling element and fluid film wave bearings, and the housing. Radiated noise is mapped from the gearbox surface to surrounding environment. The effectiveness of rolling element and fluid film wave bearings in breaking the vibro-acoustic propagation path from the gear to the housing is investigated.

Study of journal bearing dynamics using 3-dimensional motion picture graphics

Science.gov (United States)

Brewe, D. E.; Sosoka, D. J.

1985-01-01

Computer generated motion pictures of three dimensional graphics are being used to analyze journal bearings under dynamically loaded conditions. The motion pictures simultaneously present the motion of the journal and the pressures predicted within the fluid film of the bearing as they evolve in time. The correct prediction of these fluid film pressures can be complicated by the development of cavitation within the fluid. The numerical model that is used predicts the formation of the cavitation bubble and its growth, downstream movement, and subsequent collapse. A complete physical picture is created in the motion picture as the journal traverses through the entire dynamic cycle.

Squeeze-Film Air Damping of a Five-Axis Electrostatic Bearing for Rotary Micromotors.

Science.gov (United States)

Wang, Shunyue; Han, Fengtian; Sun, Boqian; Li, Haixia

2017-05-13

Air-film damping, which dominates over other losses, plays a significant role in the dynamic response of many micro-fabricated devices with a movable mass suspended by various bearing mechanisms. Modeling the damping characteristics accurately will be greatly helpful to the bearing design, control, and test in various micromotor devices. This paper presents the simulated and experimental squeeze-film air damping results of an electrostatic bearing for use in a rotary high-speed micromotor. It is shown that the boundary condition to solve the three-dimensional Reynolds equation, which governs the squeeze-film damping in the air gap between the rotor and its surrounding stator sealed in a three-layer evacuated cavity, behaves with strong cross-axis coupling characteristics. To accurately characterize the damping effect, a set of multiphysics finite-element simulations are performed by computing both the rotor velocity and the distribution of the viscous damping force acting on the rotor. The damping characteristics varying with several key structure parameters are simulated and discussed to optimize the device structure for desirable rotor dynamics. An electrical measurement method is also proposed and applied to validate the numerical results of the damping coefficients experimentally. Given that the frequency response of the electric bearing is critically dependent on the damping coefficients at atmospheric pressure, a solution to the air-film damping measurement problem is presented by taking approximate curve fitting of multi-axis experimental frequency responses. The measured squeeze-film damping coefficients for the five-axis electric bearing agrees well with the numerical solutions. This indicates that numerical multiphysics simulation is an effective method to accurately examine the air-film damping effect for complex device geometry and arbitrary boundary condition. The accurate damping coefficients obtained by FEM simulation will greatly simplify the design

Linking rigid multibody systems via controllable thin fluid films

DEFF Research Database (Denmark)

Estupinan, Edgar Alberto; Santos, Ilmar

2009-01-01

, this paper gives a theoretical contribution to the combined fields of fluid–structure interaction and vibration control. The methodology is applied to a reciprocating linear compressor, where the dynamics of the mechanical components are described with help of multibody dynamics. The crank is linked......This work deals with the mathematical modelling of multibody systems interconnected via thin fluid films. The dynamics of the fluid films can be actively controlled by means of different types of actuators, allowing significant vibration reduction of the system components. In this framework...... to the rotor via a thin fluid film, where the hydrodynamic pressure is described by the Reynolds equation, which is modified to accommodate the controllable lubrication conditions. The fluid film forces are coupled to the set of nonlinear equations that describes the dynamics of the reciprocating linear...

Approximate solution of oil film load-carrying capacity of turbulent journal bearing with couple stress flow

Science.gov (United States)

Zhang, Yongfang; Wu, Peng; Guo, Bo; Lü, Yanjun; Liu, Fuxi; Yu, Yingtian

2015-01-01

The instability of the rotor dynamic system supported by oil journal bearing is encountered frequently, such as the half-speed whirl of the rotor, which is caused by oil film lubricant with nonlinearity. Currently, more attention is paid to the physical characteristics of oil film due to an oil-lubricated journal bearing being the important supporting component of the bearing-rotor systems and its nonlinear nature. In order to analyze the lubrication characteristics of journal bearings efficiently and save computational efforts, an approximate solution of nonlinear oil film forces of a finite length turbulent journal bearing with couple stress flow is proposed based on Sommerfeld and Ocvirk numbers. Reynolds equation in lubrication of a finite length turbulent journal bearing is solved based on multi-parametric principle. Load-carrying capacity of nonlinear oil film is obtained, and the results obtained by different methods are compared. The validation of the proposed method is verified, meanwhile, the relationships of load-carrying capacity versus eccentricity ratio and width-to-diameter ratio under turbulent and couple stress working conditions are analyzed. The numerical results show that both couple stress flow and eccentricity ratio have obvious influence on oil film pressure distribution, and the proposed method approximates the load-carrying capacity of turbulent journal bearings efficiently with various width-to-diameter ratios. This research proposes an approximate solution of oil film load-carrying capacity of turbulent journal bearings with different width-to-diameter ratios, which are suitable for high eccentricity ratios and heavy loads.

Establishment of Approximate Analytical Model of Oil Film Force for Finite Length Tilting Pad Journal Bearings

Directory of Open Access Journals (Sweden)

Yongliang Wang

2015-01-01

Full Text Available Tilting pad bearings offer unique dynamic stability enabling successful deployment of high-speed rotating machinery. The model of dynamic stiffness, damping, and added mass coefficients is often used for rotordynamic analyses, and this method does not suffice to describe the dynamic behaviour due to the nonlinear effects of oil film force under larger shaft vibration or vertical rotor conditions. The objective of this paper is to present a nonlinear oil force model for finite length tilting pad journal bearings. An approximate analytic oil film force model was established by analysing the dynamic characteristic of oil film of a single pad journal bearing using variable separation method under the dynamic π oil film boundary condition. And an oil film force model of a four-tilting-pad journal bearing was established by using the pad assembly technique and considering pad tilting angle. The validity of the model established was proved by analyzing the distribution of oil film pressure and the locus of journal centre for tilting pad journal bearings and by comparing the model established in this paper with the model established using finite difference method.

Rotor Vibration Reduction via Active Hybrid Bearings

DEFF Research Database (Denmark)

Nicoletti, Rodrigo; Santos, Ilmar

2002-01-01

The use of fluid power to reduce and control rotor vibration in rotating machines is investigated. An active hybrid bearing is studied, whose main objective is to reduce wear and vibration between rotating and stationary machinery parts. By injecting pressurised oil into the oil film, through...... orifices machined in the bearing pads, one can alter the machine dynamic characteristics, thus enhancing its operational range. A mathematical model of the rotor-bearing system, as well as of the hydraulic system, is presented. Numerical results of the system frequency response show good agreement...

Nonlinear Vibration Analysis for a Jeffcott Rotor with Seal and Air-Film Bearing Excitations

Directory of Open Access Journals (Sweden)

Yuefang Wang

2010-01-01

Full Text Available The nonlinear coupling vibration and bifurcation of a high-speed centrifugal compressor with a labyrinth seal and two air-film journal bearings are presented in this paper. The rotary shaft and disk are modeled as a rigid Jeffcott rotor. Muszynska's model is used to express the seal force with multiple parameters. For air-film journal bearings, the model proposed by Zhang et al. is adopted to express unsteady bearing forces. The Runge-Kutta method is used to numerically determine the vibration responses of the disk center and the bearings. Bifurcation diagrams for transverse motion of the rotor are presented with parameters of rotation speed and pressure drop of the seal. Multiple subharmonic, periodic, and quasiperiodic motions are presented with two seal-pressure drops. The bifurcation characteristics show inherent interactions between forces of the air-film bearings and the seal, presenting more complicated rotor dynamics than the one with either of the forces alone. Bifurcation diagrams are obtained with parameters of pressure drop and seal length determined for the sake of operation safety.

On The Modeling Of Hybrid Aerostatic - Gas Journal Bearings

DEFF Research Database (Denmark)

Morosi, Stefano; Santos, Ilmar

2010-01-01

of a compressible fluid film journal bearing. Control forces are generated by injecting pressurized air into the bearing gap through orifices located on the bearing walls. A modified form of the compressible Reynolds equation for active lubrication is derived. By solving this equation, stiffness and damping......Gas journal bearing have been increasingly adopted in modern turbo-machinery applications, as they meet the demands of operation at higher rotational speeds, in clean environment and great efficiency. Due to the fact that gaseous lubricants, typically air, have much lower viscosity than more...

On The Modelling Of Hybrid Aerostatic - Gas Journal Bearings

DEFF Research Database (Denmark)

Morosi, Stefano; Santos, Ilmar

2011-01-01

modeling for hybrid lubrication of a compressible fluid film journal bearing. Additional forces are generated by injecting pressurized air into the bearing gap through orifices located on the bearing walls. A modified form of the compressible Reynolds equation for active lubrication is derived. By solving......Gas journal bearing have been increasingly adopted in modern turbo-machinery applications, as they meet the demands of operation at higher rotational speeds, in clean environment and great efficiency. Due to the fact that gaseous lubricants, typically air, have much lower viscosity than more...

Measured displacement coefficients of an adjustable hydrodynamic journal rotor bearing

OpenAIRE

Martin, J. K.

2013-01-01

In simulating a proposed machine tool grinding wheel design, a bearing system comprised a stationary spindle or shaft with fluid film bearings supporting a belt driven rotor. Two hydrodynamic bearings acted in parallel, and built into the shaft were the means to effect continuous pro-active adjustments to their performance characteristics during operation, irrespective of load, speed and other running conditions. The design is outlined, as is a specially constructed test rig for evaluating it...

Noise of oil lubricated journal bearings

International Nuclear Information System (INIS)

Rho, Byoung Hoo; Kim, Kyung Woong

2002-01-01

The purpose of the paper is to provide a procedure to calculate the noise of oil lubricated journal bearings. To do this, the nonlinear transient analysis of rotor-bearing system including rotor imbalance is performed. Acoustical properties of the bearing are investigated through frequency analysis of the pressure fluctuation of the fluid film calculated from the nonlinear analysis. Furthermore, a transmission theory of plane waves on a boundary of the outer surface of the bearing is used to obtain the sound pressure level of the bearing. Results show that the sound pressure level of the bearing can be increased with the rotational speed of the rotor although the whirl amplitude of the rotor is decreased at high speed. Noise estimating procedures presented in this paper could be an aid in the evaluation and understanding of acoustical properties of oil lubricated journal bearings

Modelling of Outer and Inner Film Oil Pressure for Floating Ring Bearing Clearance in Turbochargers

International Nuclear Information System (INIS)

Zhang Hao; Shi Zhanqun; Gu Fengshou; Ball, Andrew

2011-01-01

Floating ring bearing is widely used in turbochargers to undertake the extreme condition of high rotating speed and high operating temperature. It is also the most concerned by the designers and users alike due to its high failure rate and high maintenance cost. Any little clearance change may result in oil leakage, which in turn cause blue smoke or black smoke according to leakage types. However, there is no condition monitoring of this bearing because it is almost impossible to measure the clearance especially the inner clearance, in which the inner oil film directly bears the high speed rotation. In stead of measuring clearance directly, this paper has proposed a method that uses film pressure as a measure to monitor the bearing clearance and its variation. A non-linear mathematical model is developed by using Reynolds equations with non-linear oil film pressure. A full description of the outer and inner film is provided along both axial and radial directions. A numerical simulation is immediately carried out. Variable clearance changes are investigated using the mathematical model. Results show the relationship between clearance and film pressure.

The effect of bone cement particles on the friction of polyethylene and polyurethane knee bearings

International Nuclear Information System (INIS)

Ash, H E; Scholes, S C; Unsworth, A; Jones, E

2004-01-01

Compliant layer knee joints have been considered for use in an attempt to increase the serviceable life of artificial joints. If designed correctly, these joints should operate within the full-fluid film lubrication regime. However, adverse tribological conditions, such as the presence of bone and bone cement particles, may breach the fluid film and cause surface wear. The frictional behaviour of both polyurethane (PU) and conventional polyethylene (PE) tibial components against a metallic femoral component was therefore assessed when bone cement particles were introduced into the lubricant. The bone cement particles caused a large increase in the frictional torque of both the PE and PU bearings; however, the friction produced by the PU bearings was still considerably lower than that produced by the PE bearings. The volume of bone cement particles between each of the bearings and the resultant frictional torque both decreased over time. This occurred more quickly with the PE bearings but greater damage was caused to the surface of the PE bearings than the PU components

An investigation of the fluid-structure interaction of piston/cylinder interface

Science.gov (United States)

Pelosi, Matteo

The piston/cylinder lubricating interface represents one of the most critical design elements of axial piston machines. Being a pure hydrodynamic bearing, the piston/cylinder interface fulfills simultaneously a bearing and sealing function under oscillating load conditions. Operating in an elastohydrodynamic lubrication regime, it also represents one of the main sources of power loss due to viscous friction and leakage flow. An accurate prediction of the time changing tribological interface characteristics in terms of fluid film thickness, dynamic pressure field, load carrying ability and energy dissipation is necessary to create more efficient interface designs. The aim of this work is to deepen the understanding of the main physical phenomena defining the piston/cylinder fluid film and to discover the impact of surface elastic deformations and heat transfer on the interface behavior. For this purpose, a unique fully coupled multi-body dynamics model has been developed to capture the complex fluid-structure interaction phenomena affecting the non-isothermal fluid film conditions. The model considers the squeeze film effect due to the piston micro-motion and the change in fluid film thickness due to the solid boundaries elastic deformations caused by the fluid film pressure and by the thermal strain. The model has been verified comparing the numerical results with measurements taken on special designed test pumps. The fluid film calculated dynamic pressure and temperature fields have been compared. Further validation has been accomplished comparing piston/cylinder axial viscous friction forces with measured data. The model has been used to study the piston/cylinder interface behavior of an existing axial piston unit operating at high load conditions. Numerical results are presented in this thesis.

Steady State Thermo-Hydrodynamic Analysis of Two-Axial groove and Multilobe Hydrodynamic Bearings

Directory of Open Access Journals (Sweden)

C. Bhagat

2014-12-01

Full Text Available Steady state thermo-hydrodynamic analysis of two axial groove and multi lobe oil journal bearings is performed in this paper. To study the steady state thermo-hydrodynamic characteristics Reynolds equation is solved simultaneously along with the energy equation and heat conduction equation in bush and shaft. The effect of groove geometry, cavitation in the fluid film, the recirculation of lubricant, shaft speed has also been taken into account. Film temperature in case of three-lobe bearing is found to be high as compared to other studied bearing configurations. The data obtained from this analysis can be used conveniently in the design of such bearings, which are presented in dimensionless form.

Influence of technological factors on characteristics of hybrid fluid-film bearings

Science.gov (United States)

Koltsov, A.; Prosekova, A.; Rodichev, A.; Savin, L.

2017-08-01

The influence of the parameters of micro- and macrounevenness on the characteristics of a hybrid bearing with slotted throttling is considered in the present paper. The quantitative assumptions of calculation of pressure distribution, load capacity, lubricant flow rate and power loss due to friction in a radial hybrid bearing with slotted throttling are taken into account, considering the shape, dimensions and roughness of the support surfaces inaccuracies. Numerical simulation of processes in the lubricating layer is based on the finite-difference solution of the Reynolds equation using an uneven orthogonal computational grid with adaptive condensation. The results of computational and physical experiments are presented.

Plain bearing stresses due to forming and oil film pressure

International Nuclear Information System (INIS)

Burke-Veliz, A; Reed, P A S; Syngellakis, S; Wang, D; Wahdy, N; Merritt, D

2009-01-01

This paper describes a methodology for assessing critical stress ranges arising in automotive plain bearings during engine operations. An industry-produced and run simulation program provides information on oil film pressure and overall bearing deformation during accelerated performance tests. This code performs an elasto-hydrodynamic lubrication analysis accounting for the compliance of the housing and journal. Finite element analyses of a multilayer bearing are performed to assess the conditions responsible for possible fatigue damage over the bearing lining. The residual stresses arising from the forming and fitting process are first assessed. The stress analyses over the engine cycle show the intensity and distribution of cyclic tensile and compressive stresses in the bearing. The location of maximum stress range is found to be consistent with the damage observed in accelerated fatigue tests. Critical zones are identified in the lining for possible fatigue crack initiation and growth studies.

Plain bearing stresses due to forming and oil film pressure

Energy Technology Data Exchange (ETDEWEB)

Burke-Veliz, A; Reed, P A S; Syngellakis, S [University of Southampton, School of Engineering Sciences, Southampton SO17 1BJ (United Kingdom); Wang, D; Wahdy, N; Merritt, D, E-mail: allan.burke@itesm.m [MAHLE Engine Systems UK Ltd, 2 Central park Drive, Rugby CV23 0WE (United Kingdom)

2009-08-01

This paper describes a methodology for assessing critical stress ranges arising in automotive plain bearings during engine operations. An industry-produced and run simulation program provides information on oil film pressure and overall bearing deformation during accelerated performance tests. This code performs an elasto-hydrodynamic lubrication analysis accounting for the compliance of the housing and journal. Finite element analyses of a multilayer bearing are performed to assess the conditions responsible for possible fatigue damage over the bearing lining. The residual stresses arising from the forming and fitting process are first assessed. The stress analyses over the engine cycle show the intensity and distribution of cyclic tensile and compressive stresses in the bearing. The location of maximum stress range is found to be consistent with the damage observed in accelerated fatigue tests. Critical zones are identified in the lining for possible fatigue crack initiation and growth studies.

Hydrodynamic Fluid Film Bearings and Their Effect on the Stability of Rotating Machinery

National Research Council Canada - National Science Library

Andres, Luis S

2006-01-01

.... This design parameter shows the static performance of the bearing as rotor speed increases. Rotordynamic force coefficients are introduced and their effect on the stability of a rotor-bearing system thoroughly discussed...

The Impact of Convective Fluid Inertia Forces on Operation of Tilting-Pad Journal Bearings

Directory of Open Access Journals (Sweden)

Thomas Hagemann

2017-01-01

Full Text Available This paper presents a combination of experimental data, CFD analyses, and bearing code predictions on emergence of convective inertia fluid forces within the lube oil flow of tilting-pad journal bearings. Concordantly, experimental data and CFD analyses show a significant rise of local pressure at the transition between inlet and leading edge of tilting-pad, especially for high-speed applications with surface speeds up to 100 m/s. This effect can be related to convective inertia forces within fluid flow as cross-sections and flow character rapidly change at the pad entrance. An energy-based approach is implemented in the bearing code in order to provide enhanced boundary conditions for Reynolds equation considering this effect. As a result, predictions of bearing code achieved significant improved correlation with measured pressure distributions and CFD-data. Further, beside the local influence, a nonnegligible impact on characteristic parameters of bearing operation such as maximum temperature and stiffness and damping coefficients is observed. Finally, the results are critically analyzed and requirements to gain more distinct and reliable data are specified.

Schemes for applying active lubrication to main engine bearings

DEFF Research Database (Denmark)

Estupinan, Edgar Alberto; Santos, Ilmar

2009-01-01

-difference method. The computed bearing fluid film forces are coupled to the set of nonlinear equations that describes the dynamics of the reciprocating engine, obtained with the help of multibody dynamics (rigid components) and finite elements method (flexible components). The main equations that govern...

Synovial fluid lubrication of artificial joints: protein film formation and composition.

Science.gov (United States)

Fan, Jingyun; Myant, Connor; Underwood, Richard; Cann, Philippa

2012-01-01

Despite design improvements, wear of artificial implants remains a serious health issue particularly for Metal-on-Metal (MoM) hips where the formation of metallic wear debris has been linked to adverse tissue response. Clearly it is important to understand the fundamental lubrication mechanisms which control the wear process. It is usually assumed that MoM hips operate in the ElastoHydrodynamic Lubrication (EHL) regime where film formation is governed by the bulk fluid viscosity; however there is little experimental evidence of this. The current paper critically examines synovial fluid lubrication mechanisms and the effect of synovial fluid chemistry. Two composition parameters were chosen; protein content and pH, both of which are known to change in diseased or post-operative synovial fluid. Film thickness and wear tests were carried out for a series of model synovial fluid solutions. Two distinct film formation mechanisms were identified; an adsorbed surface film and a high-viscosity gel. The entrainment of this gel controls film formation particularly at low speeds. However wear of the femoral head still occurs and this is thought to be due primarily to a tribo-corrosion mechanisms. The implications of this new lubrication mechanism and the effect of different synovial fluid chemistries are examined. One important conclusion is that patient synovial fluid chemistry plays an important role in determining implant wear and the likelihood of failure.

Analysis of a Thrust Bearing with Flexible Pads and Flexible Supports

DEFF Research Database (Denmark)

Klit, Peder; Thomsen, Kim

2007-01-01

A theoretical analysis of a hydrodynamic thrust bearing is presented. The bearing investigated is used in an ndustrial product. The lubricant is water, but the results are valid also for other lubricants.At first the results from a 1-dimensional model for the fluid film forces and the associated...... deformation of the bearing geometry is presented. This model enlightens the influence of pad flexibility and support location and flexibility. Subsequently results from a 2-dimensional model of the bearing is presented. The model is used to carry out an optimization of the bearing design, and the obtained...

Numerical Analyses of the Non-Newtonian Flow Performance and Thermal Effect on a Bearing Coated with a High Tin Content

Directory of Open Access Journals (Sweden)

K. Mehala

2016-12-01

Full Text Available The hydrodynamic bearings are stressed by severe workings conditions, such as speed, load, and the oil will be increasingly solicit by pressure and shear. The Newtonian behavior is far from being awarded in this case, the most loaded bearings operating at very high speeds; the shear rate of the oil is of higher order. A numerical analysis of the behavior of non-Newtonian fluid for plain cylindrical journal bearing finite dimension coated with antifriction material with a high tin content, for to facilitate the accommodation of the surfaces and save the silk of the shaft in the case of a contact. this analyses is implemented using the code-ANSYS CFX, by solving the energy equation with the finite difference method, considering that laminar regime and the fluid is non Newtonian by using the power law Ostwald model, the coefficient n is equal to 1.25 and for different model such as Bingham, cross and Hereshek-Bulkley model. This study aims to better predict the non-Newtonian behavior of the oil film in bearings operating under more severe conditions. The purpose conducted during this study is to predict the effect of non-Newtonian behavior of the film; the journal bearing operating under severe conditions, the speed of rotation varies from 1000 to 9000 rpm and the bearing working under radial load 2 to 10 kN. Temperature and the pressure within the fluid film assumed non-Newtonian are high, with a coefficient n greater than 1 that is to say for viscoelastic fluids.

Simulation of the fluid structure interaction for an aerostatic bearing and a flexible substrate

NARCIS (Netherlands)

Olieslagers, R.; Wild, M. de; Melick, S. van; Knaapen, R.

2014-01-01

The fluid structure interaction for an aerostatic bearing and a substrate is solved numerically by a semi-analytical model, programmed in the software package MATLAB. This semi-analytical model uses a fluidic network of resistances and capacities to solve the pressure field in the bearing channel.

Squirt flow due to interfacial water films in hydrate bearing sediments

Directory of Open Access Journals (Sweden)

K. Sell

2018-05-01

Full Text Available Sediments containing gas hydrate dispersed in the pore space are known to show a characteristic seismic anomaly which is a high attenuation along with increasing seismic velocities. Currently, this observation cannot be fully explained albeit squirt-flow type mechanisms on the microscale have been speculated to be the cause. Recent major findings from in situ experiments, using the gas in excess and water in excess formation method, and coupled with high-resolution synchrotron-based X-ray micro-tomography, have revealed the systematic presence of thin water films between the quartz grains and the encrusting hydrate. The data obtained from these experiments underwent an image processing procedure to quantify the thicknesses and geometries of the aforementioned interfacial water films. Overall, the water films vary from sub-micrometer to a few micrometers in thickness. In addition, some of the water films interconnect through water bridges. This geometrical analysis is used to propose a new conceptual squirt flow model for hydrate bearing sediments. A series of numerical simulations is performed considering variations of the proposed model to study seismic attenuation caused by such thin water films. Our results support previous speculation that squirt flow can explain high attenuation at seismic frequencies in hydrate bearing sediments, but based on a conceptual squirt flow model which is geometrically different than those previously considered.

Nonlinear dynamics of a flexible rotor supported by turbulent journal bearings with couple stress fluid

International Nuclear Information System (INIS)

Lo, C.-Y.; Chang-Jian, C.-W.

2008-01-01

This study presents a dynamic analysis of a rotor supported by two turbulent flow model journal bearings and lubricated with couple stress fluid under nonlinear suspension. The dynamics of the rotor center and bearing center is studied. The dynamic equations are solved using the Runge-Kutta method. The analysis methods employed in this study is inclusive of the dynamic trajectories of the rotor center and bearing center, power spectra, Poincare maps and bifurcation diagrams. The maximum Lyapunov exponent analysis is also used to identify the onset of chaotic motion. The results show that the values of dimensionless parameters l* strongly influence dynamic motions of bearing and rotor centre. It is found that couple stress fluid improve the stability of the system when l* > 0.4 even if the flow of this system is turbulent. We also demonstrated that the dimensionless rotational speed ratios s and the dimensionless unbalance parameter β are also significant system parameters. The modeling results thus obtained by using the method proposed in this paper can be employed to predict the stability of the rotor-bearing system and the undesirable behavior of the rotor and bearing center can be avoided

A computational model for doctoring fluid films in gravure printing

Energy Technology Data Exchange (ETDEWEB)

Hariprasad, Daniel S., E-mail: dshari@unm.edu [Center for Micro-Engineered Materials, University of New Mexico, Albuquerque, New Mexico 87131-0001 (United States); Grau, Gerd [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, California 94720-1770 (United States); Schunk, P. Randall [Center for Micro-Engineered Materials, University of New Mexico, Albuquerque, New Mexico 87131-0001 (United States); Advanced Materials Laboratory, Sandia National Laboratories, Albuquerque, New Mexico 87185-0826 (United States); Department of Chemical and Biological Engineering, University of New Mexico, Albuquerque, New Mexico 87131-0001 (United States); Tjiptowidjojo, Kristianto [Center for Micro-Engineered Materials, University of New Mexico, Albuquerque, New Mexico 87131-0001 (United States); Department of Chemical and Biological Engineering, University of New Mexico, Albuquerque, New Mexico 87131-0001 (United States)

2016-04-07

The wiping, or doctoring, process in gravure printing presents a fundamental barrier to resolving the micron-sized features desired in printed electronics applications. This barrier starts with the residual fluid film left behind after wiping, and its importance grows as feature sizes are reduced, especially as the feature size approaches the thickness of the residual fluid film. In this work, various mechanical complexities are considered in a computational model developed to predict the residual fluid film thickness. Lubrication models alone are inadequate, and deformation of the doctor blade body together with elastohydrodynamic lubrication must be considered to make the model predictive of experimental trends. Moreover, model results demonstrate that the particular form of the wetted region of the blade has a significant impact on the model's ability to reproduce experimental measurements.

Bifurcation and Nonlinear Dynamic Analysis of Externally Pressurized Double Air Films Bearing System

Directory of Open Access Journals (Sweden)

Cheng-Chi Wang

2014-01-01

Full Text Available This paper studies the chaotic and nonlinear dynamic behaviors of a rigid rotor supported by externally pressurized double air films (EPDAF bearing system. A hybrid numerical method combining the differential transformation method and the finite difference method is used to calculate pressure distribution of EPDAF bearing system and bifurcation phenomenon of rotor center orbits. The results obtained for the orbits of the rotor center are in good agreement with those obtained using the traditional finite difference approach. The results presented summarize the changes which take place in the dynamic behavior of the EPDAF bearing system as the rotor mass and bearing number are increased and therefore provide a useful guideline for the bearing system.

Evaluation of Oil Film Pressure and Temperature of an Elliptical Journal Bearing - An Experimental Study

Directory of Open Access Journals (Sweden)

A. Singla

2016-03-01

Full Text Available The present study is aimed at experimental evaluation of both oil film pressure and temperature at the central plane of finite elliptical journal bearing configuration. These parameters have been obtained by running the machine at various speeds under different applied loads ranging from 500 N to 2000 N using three different grades of oil (HYDROL 32, 68 and 150. The data has been obtained through a test rig which is capable of measuring both pressure and temperature at the same location on the elliptical bearing profile. An elliptical journal bearing with journal diameter=100 mm, L/D ratio=1.0, Ellipticity Ratio=1.0 and radial clearance=0.1 mm has been designed and tested to access the pressure and temperature rise of the oil film at the central plane of the bearing. Two different lobes of positive pressure have been obtained for elliptical bearing which results in smaller area for cavitation zone and accounts for better thermal stability. Also, with the increase in load both pressure and temperature of an oil film increases for all the three grades of oil. Experimentally, it has been established that the HYDROL 68 is suitable grade of lubricating oil which gives the optimum rise of pressure and temperate under all operating conditions among the lubricating oils under study.

Analysis of single oil-bearing fluid inclusions in mid-Proterozoic sandstones (Roper Group, Australia)

Science.gov (United States)

Siljeström, Sandra; Volk, Herbert; George, Simon C.; Lausmaa, Jukka; Sjövall, Peter; Dutkiewicz, Adriana; Hode, Tomas

2013-12-01

Hydrocarbons and organic biomarkers extracted from black shales and other carbonaceous sedimentary rocks are valuable sources of information on the biodiversity and environment of early Earth. However, many Precambrian hydrocarbons including biomarkers are suspected of being younger contamination. An alternative approach is to study biomarkers trapped in oil-bearing fluid inclusions by bulk crushing samples and subsequently analysing the extracted hydrocarbons with gas chromatography-mass spectrometry. However, this method does not constrain the hydrocarbons to one particular oil inclusion, which means that if several different generations of oil inclusions are present in the sample, a mix of the content from these oil inclusions will be analysed. In addition, samples with few and/or small inclusions are often below the detection limit. Recently, we showed that it is possible to detect organic biomarkers in single oil-bearing fluid inclusions using time-of-flight secondary ion mass spectrometry (ToF-SIMS). In the present study, single fluid inclusion analysis has been performed on Proterozoic samples for the first time. Four individual oil-bearing fluid inclusions, found in 1430 Ma sandstone from the Roper Superbasin in Northern Australia, were analysed with ToF-SIMS. The ToF-SIMS spectra of the oil in the different inclusions are very similar to each other and are consistent with the presence of n-alkanes/branched alkanes, monocyclic alkanes, bicyclic alkanes, aromatic hydrocarbons, and tetracyclic and pentacyclic hydrocarbons. These results are in agreement with those obtained from bulk crushing of inclusions trapped in the same samples. The capability to analyse the hydrocarbon and biomarker composition of single oil-bearing fluid inclusions is a major breakthrough, as it opens up a way of obtaining molecular compositional data on ancient oils without the ambiguity of the origin of these hydrocarbons. Additionally, this finding suggests that it will be possible

On the matter of synovial fluid lubrication: implications for Metal-on-Metal hip tribology.

Science.gov (United States)

Myant, Connor; Cann, Philippa

2014-06-01

Artificial articular joints present an interesting, and difficult, tribological problem. These bearing contacts undergo complex transient loading and multi axes kinematic cycles, over extremely long periods of time (>10 years). Despite extensive research, wear of the bearing surfaces, particularly metal-metal hips, remains a major problem. Comparatively little is known about the prevailing lubrication mechanism in artificial joints which is a serious gap in our knowledge as this determines film formation and hence wear. In this paper we review the accepted lubrication models for artificial hips and present a new concept to explain film formation with synovial fluid. This model, recently proposed by the authors, suggests that interfacial film formation is determined by rheological changes local to the contact and is driven by aggregation of synovial fluid proteins. The implications of this new mechanism for the tribological performance of new implant designs and the effect of patient synovial fluid properties are discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

The R and D D's bearing test benches

International Nuclear Information System (INIS)

Vialettes, J.M.

1997-01-01

In power generation plants, rotating machines are involved in energy transformation processes and safety systems. The bearings supporting the rotors and the thrust bearings play a crucial role in the reliability of these machines. The phenomena encountered straddle several disciplines: hydrodynamics, tribology, thermomechanics, materials and vibrations in a specific environment, namely: thin fluid film, solid mechanical components and shaft rotation. Means of analysing the behaviour of these components (bearings and thrust bearings) have been developed and implemented. These consists of the EDYOS (Etude Dynamique des Organes de Supportage) code for dynamically studying bearing devices and several related bench tests. In reality, in order to understand the complex physical phenomena encountered in these components, it is vital to carry out analyses and experimental validations. Since these investigations cannot be carried out on actual machines, test benches have been built which can subject the sample bearings to the equivalent stresses. (author)

Particle-bearing currents in uniform density and two-layer fluids

Science.gov (United States)

Sutherland, Bruce R.; Gingras, Murray K.; Knudson, Calla; Steverango, Luke; Surma, Christopher

2018-02-01

Lock-release gravity current experiments are performed to examine the evolution of a particle bearing flow that propagates either in a uniform-density fluid or in a two-layer fluid. In all cases, the current is composed of fresh water plus micrometer-scale particles, the ambient fluid is saline, and the current advances initially either over the surface as a hypopycnal current or at the interface of the two-layer fluid as a mesopycnal current. In most cases the tank is tilted so that the ambient fluid becomes deeper with distance from the lock. For hypopycnal currents advancing in a uniform density fluid, the current typically slows as particles rain out of the current. While the loss of particles alone from the current should increase the current's buoyancy and speed, in practice the current's speed decreases because the particles carry with them interstitial fluid from the current. Meanwhile, rather than settling on the sloping bottom of the tank, the particles form a hyperpycnal (turbidity) current that advances until enough particles rain out that the relatively less dense interstitial fluid returns to the surface, carrying some particles back upward. When a hypopycnal current runs over the surface of a two-layer fluid, the particles that rain out temporarily halt their descent as they reach the interface, eventually passing through it and again forming a hyperpycnal current. Dramatically, a mesopycnal current in a two-layer fluid first advances along the interface and then reverses direction as particles rain out below and fresh interstitial fluid rises above.

On the Possibilities of Decreasing Power Loss in Large Tilting Pad Thrust Bearings

OpenAIRE

Wasilczuk, Michal; Rotta, Grzegorz

2013-01-01

Different systems of direct oil supply have been developed in order to facilitate efficient introduction of fresh lubricant to the oil gap and reduction of churning power loss in tilting pad thrust bearings. Up to now there is no documented application of the supply groove in large thrust bearings used in water power plants. The results of modeling lubricant flow in the lubricating groove of a thrust bearing pad will be presented in the paper. CFD software was used to carry out fluid film cal...

Au-bearing magnetite mineralizaion in Kashmar (alteration, mineralization, geochemistry, geochemistry and fluid inclusions;

Directory of Open Access Journals (Sweden)

Alireza Almasi

2017-02-01

Full Text Available Introduction The study area is located in the central part of the Khaf- Kashmar- Bardaskan volcano-plotunic belt (briefly KKBB. Several IOCG deposits such as Tanourjeh Au-bearing magnetite deposit and Kuh-e-Zar Specularite-rich Au deposit have been explored in KKBB. Geology, alteration, mineralization, geochemistry and fluid inclusion results in Kashmar suggest the IOCG type Au-bearing magnetite mineralization. These IOCG deposits at KKBB form at an active continental arc related to SSZ-type Sabzevar oceanic subduction. Materials and methods Use of Landsat 7+, IRS and Aster satellites. Petrography and alteration Studies in 150 thin sections of volcanic and intrusive rocks. Sampling of ore-bearing quartz vein and mineralography. Preparation of 28 geochemistry samples by the chip composite method of ore-bearing quartz vein and analyzing them in the ACME laboratory by Aqua Regia 1DX1. Fluid inclusions studies of 14 samples of quartz and barite related to the ore minerals of ore-bearing quartz vein by THM600 stage of Linkam company. Results Magmatic events in Kashmar occur at Paleocene-Eocene and include: (1 old mafic - intermediate volcano-plutonic series; (2 felsic volcanic and granitoids; and (3 parallel swarm dykes which are youngest (Almasi et al., 2016. Geochemically, Kashmar rocks are metaluminous to highly peraluminous and Tholeitic to calc-alkaline and shoshonitic in composition (Almasi et al., 2016. The field characteristics, together with isotope and geochemical analyses show that all rock types are essentially co-magmatic and post-collisional I-type (Almasi et al., 2016. Alteration of Kashmar is described in two ways: (1 intense ellipsoidal-linear Argillic-Sillicification and low sericitic with Silica caps and with medium widespread and propylitic alterations in triple regions, next to Dorouneh fault; and (2 Medium Hematite-Carbonate-Chlorite-Silicification alterations in Kamarmard heights. In parts of near the Doruneh fault, sometimes

Lubrication analysis of the thrust bearing in the main coolant pump of SMART

International Nuclear Information System (INIS)

Lee, J. S.; Park, J. S.; Kim, J. H.; Hur, H.; Kim, J. I.

2001-01-01

Thrust bearing and journal bearings are installed in the main coolant pump for SMART to support the rotating shaft with proper lubrication. The canned motor type main coolant pumps are arranged vertically on the reactor vessel and especially the MCP bearings are lubricated with water without external lubricating oil supply. Because axial load capacity of the thrust bearing can hardly meet requirement to acquire hydrodynamic or fluid film lubrication state, self-lubrication characteristics of silicon graphite meterials would be needed. Lubricational analysis method for thrust bearing for the main coolant pump of SMART is proposed, and lubricational characteristics of the bearing generated by solving the Reynolds equation are examined in this paper

Arthrosis of the ankle evaluated on films in weight-bearing position

International Nuclear Information System (INIS)

Bauer, M.; Bergstroem, B.; Hemborg, A.

1979-01-01

About 7 years after a malleolar fracture 113 patients were examined for development of arthrosis. The addition of films exposed in weight-bearing position with a.p. beam direction to views of the ankle joint exposed in supine position did not contribute to the diagnosis of arthrosis. (Auth.)

Measurement of oil film thickness and friction force on a guide shoe bearing

DEFF Research Database (Denmark)

Vølund, Anders

2002-01-01

An experimental program was carried out in order to reveal oil film thickness, and friction force of the guide shoe bearing of a large two stroke marine diesel engine. The experiment was conducted on a full size engine located at the research facility at MAN B&W Diesel A/S. The experiment...... was conducted such that the influence from the experiment on the characteristics were as small as possible. The objective of the experiment was to determine the frictional loss of this bearing and to check whether a suggested numerical model was applicable or not. Some future aspects for this bearing...

Controllable sliding bearings and controllable lubrication principles-an overview

DEFF Research Database (Denmark)

Santos, Ilmar F.

2018-01-01

-mechanical actuators have been coupled to such bearings. Depending on (i) the actuator type; (ii) the actuation principle, i.e., hydraulic, pneumatic, piezoelectric or magnetic among others; and (iii) how such an actuator is coupled to the sliding bearings, different regulation and control actions of fluid film...... bearing gap and its preload via moveable and compliant sliding surfaces; and (d) the control of the lubricant viscosity. All four parameters, i.e., pressure, flow (velocity profiles), gap and viscosity, are explicit parameters in the modified form of Reynolds' equations for active lubrication....... In this framework, this paper gives one main original contribution to the state-of-the-art of radial sliding bearings and controllable lubrication: a comprehensive overview about the different types of controllable sliding bearings and principles used by several authors. The paper ends with some conclusive remarks...

Numerical investigation of cavitation flow in journal bearing geometry

Science.gov (United States)

Riedel, M.; Schmidt, M.; Stücke, P.

2013-04-01

The appearance of cavitation is still a problem in technical and industrial applications. Especially in automotive internal combustion engines, hydrodynamic journal bearings are used due to their favourable wearing quality and operating characteristics. Cavitation flows inside the bearings reduces the load capacity and leads to a risk of material damages. Therefore an understanding of the complex flow phenomena inside the bearing is necessary for the design development of hydrodynamic journal bearings. Experimental investigations in the fluid domain of the journal bearing are difficult to realize founded by the small dimensions of the bearing. In the recent years more and more the advantages of the computational fluid dynamics (CFD) are used to investigate the detail of the cavitation flows. The analysis in the paper is carried out in a two-step approach. At first an experimental investigation of journal bearing including cavitation is selected from the literature. The complex numerical model validated with the experimental measured data. In a second step, typically design parameters, such as a groove and feed hole, which are necessary to distribute the oil supply across the gap were added into the model. The paper reflects on the influence of the used design parameters and the variation of the additional supply flow rate through the feed hole regarding to cavitation effects in the bearing. Detailed pictures of the three-dimensional flow structures and the cavitation regions inside the flow film of the bearing are presented.

Numerical investigation of cavitation flow in journal bearing geometry

Directory of Open Access Journals (Sweden)

Stücke P.

2013-04-01

Full Text Available The appearance of cavitation is still a problem in technical and industrial applications. Especially in automotive internal combustion engines, hydrodynamic journal bearings are used due to their favourable wearing quality and operating characteristics. Cavitation flows inside the bearings reduces the load capacity and leads to a risk of material damages. Therefore an understanding of the complex flow phenomena inside the bearing is necessary for the design development of hydrodynamic journal bearings. Experimental investigations in the fluid domain of the journal bearing are difficult to realize founded by the small dimensions of the bearing. In the recent years more and more the advantages of the computational fluid dynamics (CFD are used to investigate the detail of the cavitation flows. The analysis in the paper is carried out in a two-step approach. At first an experimental investigation of journal bearing including cavitation is selected from the literature. The complex numerical model validated with the experimental measured data. In a second step, typically design parameters, such as a groove and feed hole, which are necessary to distribute the oil supply across the gap were added into the model. The paper reflects on the influence of the used design parameters and the variation of the additional supply flow rate through the feed hole regarding to cavitation effects in the bearing. Detailed pictures of the three-dimensional flow structures and the cavitation regions inside the flow film of the bearing are presented.

An approach for including the stiffness and damping of elastohydrodynamic point contacts in deep groove ball bearing equilibrium models

Science.gov (United States)

Nonato, Fábio; Cavalca, Katia L.

2014-12-01

This work presents a methodology for including the Elastohydrodynamic (EHD) film effects to a lateral vibration model of a deep groove ball bearing by using a novel approximation for the EHD contacts by a set of equivalent nonlinear spring and viscous damper. The fitting of the equivalent contact model used the results of a transient multi-level finite difference EHD algorithm to adjust the dynamic parameters. The comparison between the approximated model and the finite difference simulated results showed a suitable representation of the stationary and dynamic contact behaviors. The linear damping hypothesis could be shown as a rough representation of the actual hysteretic behavior of the EHD contact. Nevertheless, the overall accuracy of the model was not impaired by the use of such approximation. Further on, the inclusion of the equivalent EHD contact model is equated for both the restoring and the dissipative components of the bearing's lateral dynamics. The derived model was used to investigate the effects of the rolling element bearing lubrication on the vibration response of a rotor's lumped parameter model. The fluid film stiffening effect, previously only observable by experimentation, could be quantified using the proposed model, as well as the portion of the bearing damping provided by the EHD fluid film. Results from a laboratory rotor-bearing test rig were used to indirectly validate the proposed contact approximation. A finite element model of the rotor accounting for the lubricated bearing formulation adequately portrayed the frequency content of the bearing orbits observed on the test rig.

Experimental contribution to the study of gas bearings

International Nuclear Information System (INIS)

Gobert, G.

1962-01-01

Developments for gas-lubricated bearings are discussed. The study of how the fluid film behaves compared to what one can expect is discussed. Various devices are described which have allowed us to go up to peripheral velocity greater than 400 m/s, leading to rotational speed of several thousand revolutions per second. This is obtained by using an automatic setting for the distance between fixed and rotating walls. (author) [fr

A study on synchronously whirling motion of hydrodynamic journal bearings

International Nuclear Information System (INIS)

Rho, Byoung Hoo; Kim, Kyung Woong

2001-01-01

In this paper, a control algorithm which is synchronously excitation the bearing with whirl speed of rotor is employed to suppress the whirl instability and unbalance response of the rotor-bearing system. Also, the cavitation algorithm implementing the Jakobsson-Floberg-Olsson boundary condition is adopted to predict cavitation regions in the fluid film more accurately than a conventional analysis with the Renolds condition. The stabilities and unbalance responses of the rotor-bearing system are investigated for various control gains and phase differences between the bearing and journal motion. It is shown that the unbalance response of the system can be greatly improved by synchronous control of the bearing, and there is an optimum phase difference, which gives the minimum unbalance response of the system, for given operating condition. It is also found that the onset speed of the instability can be greatly increased by synchronous control of the bearing

A study on synchronously whirling motion of hydrodynamic journal bearings

Energy Technology Data Exchange (ETDEWEB)

Rho, Byoung Hoo; Kim, Kyung Woong [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

2001-09-01

In this paper, a control algorithm which is synchronously excitation the bearing with whirl speed of rotor is employed to suppress the whirl instability and unbalance response of the rotor-bearing system. Also, the cavitation algorithm implementing the Jakobsson-Floberg-Olsson boundary condition is adopted to predict cavitation regions in the fluid film more accurately than a conventional analysis with the Renolds condition. The stabilities and unbalance responses of the rotor-bearing system are investigated for various control gains and phase differences between the bearing and journal motion. It is shown that the unbalance response of the system can be greatly improved by synchronous control of the bearing, and there is an optimum phase difference, which gives the minimum unbalance response of the system, for given operating condition. It is also found that the onset speed of the instability can be greatly increased by synchronous control of the bearing.

Calculation of Oil Film Thickness from Damping Coefficients for a Piston Ring in an Internal Combustion Engine

DEFF Research Database (Denmark)

Christiansen, Jens; Klit, Peder; Vølund, Anders

2007-01-01

engine. The basic idea is to use the fluid film damping coefficients to estimate the film thickness variation for a piston ring under cyclic varying load. Reynolds Equation is solved for a piston ring and the oil film thickness is determined. In this analysis hydrodynamic lubrication is assumed......In 1966 Jorgen W. Lund published an approach to find the dynamic coefficients of a journal bearing by a first order perturbation of the Reynold's equation. These coefficients made it possible to perform a rotor-bearing stability analysis for a statically loaded bearing. In the mid seventies Jorgen...

Meniscal Tear Film Fluid Dynamics Near Marx’s Line

KAUST Repository

Zubkov, V. S.

2013-07-03

Extensive studies have explored the dynamics of the ocular surface fluid, though theoretical investigations are typically limited to the use of the lubrication approximation, which is not guaranteed to be uniformly valid a-priori throughout the tear meniscus. However, resolving tear film behaviour within the meniscus and especially its apices is required to characterise the flow dynamics where the tear film is especially thin, and thus most susceptible to evaporatively induced hyperosmolarity and subsequent epithelial damage. Hence, we have explored the accuracy of the standard lubrication approximation for the tear film by explicit comparisons with the 2D Navier-Stokes model, considering both stationary and moving eyelids. Our results demonstrate that the lubrication model is qualitatively accurate except in the vicinity of the eyelids. In particular, and in contrast to lubrication theory, the solution of the full Navier-Stokes equations predict a distinct absence of fluid flow, and thus convective mixing in the region adjacent to the tear film contact line. These observations not only support emergent hypotheses concerning the formation of Marx\\'s line, a region of epithelial cell staining adjacent to the contact line on the eyelid, but also enhance our understanding of the pathophysiological consequences of the flow profile near the tear film contact line. © 2013 Society for Mathematical Biology.

Evaluation of datum unit for diagnostics of journal-bearing systems

International Nuclear Information System (INIS)

Jeon, Byung Chul; Jung, Joon Ha; Youn, Byeng Doog; Kim, Yeon Whan; Bae, Yong Chae

2015-01-01

Journal bearings support rotors using fluid film between the rotor and the stator. Generally, journal bearings are used in large rotor systems such as turbines in a power plant, because even in high-speed and load conditions, journal bearing systems run in a stable condition. To enhance the reliability of journal-bearing systems, in this paper, we study health-diagnosis algorithms that are based on the supervised learning method. Specifically, this paper focused on defining the unit of features, while other previous papers have focused on defining various features of vibration signals. We evaluate the features of various lengths or units on the separable ability basis. From our results, we find that one cycle datum in the time-domain and 60 cycle datum in the frequency domain are the optimal datum units for real-time journal-bearing diagnosis systems

Evaluation of datum unit for diagnostics of journal-bearing systems

Energy Technology Data Exchange (ETDEWEB)

Jeon, Byung Chul; Jung, Joon Ha; Youn, Byeng Doog [Dept. of Mechanical and Aerospace Engineering, Seoul National University, Seoul (Korea, Republic of); Kim, Yeon Whan; Bae, Yong Chae [Power Generation Laboratory, KEPCO Research Institute, Daejeon (Korea, Republic of)

2015-08-15

Journal bearings support rotors using fluid film between the rotor and the stator. Generally, journal bearings are used in large rotor systems such as turbines in a power plant, because even in high-speed and load conditions, journal bearing systems run in a stable condition. To enhance the reliability of journal-bearing systems, in this paper, we study health-diagnosis algorithms that are based on the supervised learning method. Specifically, this paper focused on defining the unit of features, while other previous papers have focused on defining various features of vibration signals. We evaluate the features of various lengths or units on the separable ability basis. From our results, we find that one cycle datum in the time-domain and 60 cycle datum in the frequency domain are the optimal datum units for real-time journal-bearing diagnosis systems.

Identification Methods and Test Results for Tilting Pad and Fixed Geometry Journal Bearing Dynamic Coefficients – A Review

Directory of Open Access Journals (Sweden)

T.W. Dimond

2009-01-01

Full Text Available Fluid film journal bearings (FFBs are used to support high-speed rotors in turbomachinery which often operate above the rotor first bending critical speed. The FFBs provide both lateral support and dynamic coefficients: stiffness, damping, and mass terms, related to machine vibrations. Detailed numerical values of the bearing dynamic characteristics are necessary for proper design and operation of rotating machinery.

Friction and Lubrication of Large Tilting-Pad Thrust Bearings

Directory of Open Access Journals (Sweden)

Michał Wasilczuk

2015-04-01

Full Text Available Fluid film bearings have been extensively used in the industry because of their unbeatable durability and extremely low friction coefficient, despite a very low coefficient of friction dissipation of energy being noticeable, especially in large bearings. Lubricating systems of large tilting pad thrust bearings utilized in large, vertical shaft hydrogenerators are presented in this paper. A large amount of heat is generated due to viscous shearing of the lubricant large tilting pad thrust bearings, and this requires systems for forced cooling of the lubricant. In the dominant bath lubrication systems, cooling is realized by internal coolers or external cooling systems, with the latter showing some important advantages at the cost of complexity and also, potentially, lower reliability. Substantial losses in the bearings, reaching 1 MW in extreme cases, are a good motivation for the research and development aimed at reducing them. Some possible methods and their potential efficiency, along with some effects already documented, are also described in the paper.

Development of precipitator of fluid film type

International Nuclear Information System (INIS)

Liu Yupu

1987-01-01

The precipitator of fluid film type is developed for the determination of fuel element cladding failure of water-cooled reactor. It integrates the scrubber, precipitator and detector. The jet of element cooling water automatically circulates carrier gas and the flow water film transfers precipitates onto the surface of centre electrode. Three different types are designed. On the special test loop, the uranium sample pellets of simulating cladding failure is measured. The sensitivity of precipitators, saturated precipitation voltage, incremental speed of signal, speed of driving out precipitates and the contents of the precipitates are determined. The test shows that the precipitators are highly sensitive, reliable, cheap and easy to operate

Thin-Film Magnetic-Field-Response Fluid-Level Sensor for Non-Viscous Fluids

Science.gov (United States)

Woodard, Stanley E.; Shams, Qamar A.; Fox, Robert L.; Taylor, Bryant D.

2008-01-01

An innovative method has been developed for acquiring fluid-level measurements. This method eliminates the need for the fluid-level sensor to have a physical connection to a power source or to data acquisition equipment. The complete system consists of a lightweight, thin-film magnetic-field-response fluid-level sensor (see Figure 1) and a magnetic field response recorder that was described in Magnetic-Field-Response Measurement-Acquisition System (LAR-16908-1), NASA Tech Briefs, Vol. 30, No. 6 (June 2006), page 28. The sensor circuit is a capacitor connected to an inductor. The response recorder powers the sensor using a series of oscillating magnetic fields. Once electrically active, the sensor responds with its own harmonic magnetic field. The sensor will oscillate at its resonant electrical frequency, which is dependent upon the capacitance and inductance values of the circuit.

Dynamic characteristics of Non Newtonian fluid Squeeze film damper

Science.gov (United States)

Palaksha, C. P.; Shivaprakash, S.; Jagadish, H. P.

2016-09-01

The fluids which do not follow linear relationship between rate of strain and shear stress are termed as non-Newtonian fluid. The non-Newtonian fluids are usually categorized as those in which shear stress depends on the rates of shear only, fluids for which relation between shear stress and rate of shear depends on time and the visco inelastic fluids which possess both elastic and viscous properties. It is quite difficult to provide a single constitutive relation that can be used to define a non-Newtonian fluid due to a great diversity found in its physical structure. Non-Newtonian fluids can present a complex rheological behaviour involving shear-thinning, viscoelastic or thixotropic effects. The rheological characterization of complex fluids is an important issue in many areas. The paper analyses the damping and stiffness characteristics of non-Newtonian fluids (waxy crude oil) used in squeeze film dampers using the available literature for viscosity characterization. Damping and stiffness characteristic will be evaluated as a function of shear strain rate, temperature and percentage wax concentration etc.

Magnetic Fluid-Based Squeeze Film Behaviour in Curved Porous-Rotating Rough Annular Plates and Elastic Deformation Effect

Directory of Open Access Journals (Sweden)

M. E. Shimpi

2012-01-01

Full Text Available Efforts have been directed to study and analyze the squeeze film performance between rotating transversely rough curved porous annular plates in the presence of a magnetic fluid lubricant considering the effect of elastic deformation. A stochastic random variable with nonzero mean, variance, and skewness characterizes the random roughness of the bearing surfaces. With the aid of suitable boundary conditions, the associated stochastically averaged Reynolds' equation is solved to obtain the pressure distribution in turn, which results in the calculation of the load-carrying capacity. The graphical representations establish that the transverse roughness, in general, adversely affects the performance characteristics. However, the magnetization registers a relatively improved performance. It is found that the deformation causes reduced load-carrying capacity which gets further decreased by the porosity. This investigation tends to indicate that the adverse effect of porosity, standard deviation and deformation can be compensated to certain extent by the positive effect of the magnetic fluid lubricant in the case of negatively skewed roughness by choosing the rotational inertia and the aspect ratio, especially for suitable ratio of curvature parameters.

Comparative study of the biodegradability of porous silicon films in simulated body fluid.

Science.gov (United States)

Peckham, J; Andrews, G T

2015-01-01

The biodegradability of oxidized microporous, mesoporous and macroporous silicon films in a simulated body fluid with ion concentrations similar to those found in human blood plasma were studied using gravimetry. Film dissolution rates were determined by periodically weighing the samples after removal from the fluid. The dissolution rates for microporous silicon were found to be higher than those for mesoporous silicon of comparable porosity. The dissolution rate of macroporous silicon was much lower than that for either microporous or mesoporous silicon. This is attributed to the fact that its specific surface area is much lower than that of microporous and mesoporous silicon. Using an equation adapted from [Surf. Sci. Lett. 306 (1994), L550-L554], the dissolution rate of porous silicon in simulated body fluid can be estimated if the film thickness and specific surface area are known.

Mystery of Foil Air Bearings for Oil-free Turbomachinery Unlocked: Load Capacity Rule-of-thumb Allows Simple Estimation of Performance

Science.gov (United States)

DellaCorte, Christopher; Valco, Mark J.

2002-01-01

The Oil-Free Turbomachinery team at the NASA Glenn Research Center has unlocked one of the mysteries surrounding foil air bearing performance. Foil air bearings are self-acting hydrodynamic bearings that use ambient air, or any fluid, as their lubricant. In operation, the motion of the shaft's surface drags fluid into the bearing by viscous action, creating a pressurized lubricant film. This lubricating film separates the stationary foil bearing surface from the moving shaft and supports load. Foil bearings have been around for decades and are widely employed in the air cycle machines used for cabin pressurization and cooling aboard commercial jetliners. The Oil-Free Turbomachinery team is fostering the maturation of this technology for integration into advanced Oil-Free aircraft engines. Elimination of the engine oil system can significantly reduce weight and cost and could enable revolutionary new engine designs. Foil bearings, however, have complex elastic support structures (spring packs) that make the prediction of bearing performance, such as load capacity, difficult if not impossible. Researchers at Glenn recently found a link between foil bearing design and load capacity performance. The results have led to a simple rule-of-thumb that relates a bearing's size, speed, and design to its load capacity. Early simple designs (Generation I) had simple elastic (spring) support elements, and performance was limited. More advanced bearings (Generation III) with elastic supports, in which the stiffness is varied locally to optimize gas film pressures, exhibit load capacities that are more than double those of the best previous designs. This is shown graphically in the figure. These more advanced bearings have enabled industry to introduce commercial Oil-Free gas-turbine-based electrical generators and are allowing the aeropropulsion industry to incorporate the technology into aircraft engines. The rule-of-thumb enables engine and bearing designers to easily size and

Performance of Infinitely Wide Parabolic and Inclined Slider Bearings Lubricated with Couple Stress or Magnetic Fluids

Science.gov (United States)

Oladeinde, Mobolaji Humphrey; Akpobi, John Ajokpaoghene

2011-10-01

The hydrodynamic and magnetohydrodynamic (MHD) lubrication problem of infinitely wide inclined and parabolic slider bearings is solved numerically using the finite element method. The bearing configurations are discretized into three-node isoparametric quadratic elements. Stiffness integrals obtained from the weak form of the governing equations are solved using Gauss quadrature to obtain a finite number of stiffness matrices. The global system of equations obtained from enforcing nodal continuity of pressure for the bearings are solved using the Gauss-Seidel iterative scheme with a convergence criterion of 10-10. Numerical computations reveal that, when compared for similar profile and couple stress parameters, greater pressure builds up in a parabolic slider compared to an inclined slider, indicating a greater wedge effect in the parabolic slider. The parabolic slider bearing is also shown to develop a greater load capacity when lubricated with magnetic fluids. The superior performance of parabolic slider bearing is more pronounced at greater Hartmann numbers for identical bearing structural parameters. It is also shown that when load carrying capacity is the yardstick for comparison, the parabolic slider bearings are superior to the inclined bearings when lubricated with couple stress or magnetic lubricants.

Experimental Investigation of Biotite-Rich Schist Reacting with B-Bearing Fluids at Upper Crustal Conditions and Correlated Tourmaline Formation

Directory of Open Access Journals (Sweden)

Andrea Orlando

2017-08-01

Full Text Available Fluid–rock interaction experiments between a biotite-rich schist (from Mt. Calamita Formation, Elba Island, Italy and B-bearing aqueous fluids were carried out at 500–600 °C and 100–130 MPa. The experiments have been carried out in order to reproduce the reaction, which would have produced tourmalinisation of the biotite schist, supposedly by circulation of magmatic fluids issued from leucogranitic dykes. The reacting fluids were either NaCl-free or NaCl-bearing (20 wt % aqueous solutions, with variable concentration of H3BO3 (0.01–3.2 M. The experimental results show that tourmaline (belonging to the alkali group crystallise under high-temperature and upper crustal conditions (500–600 °C, 100–130 MPa when H3BO3 concentration in the system is greater than 1.6 M. The composition of tourmaline is either dravitic (Mg-rich or schorlitic (Fe-rich, depending if an NaCl-bearing or NaCl-free aqueous solution is used. In the first case, a significant amount of Fe released from biotite dissolution remains in the Cl-rich solution resulting from the experiment. By contrast, when pure water is used, Na/K exchange in feldspars makes Na available for tourmaline crystallisation. The high concentration of Fe in the residual fluid has an important metallogenic implication because it indicates that the interaction between the saline B-rich fluid of magmatic derivation and biotite-rich schists, besides producing tourmalinisation, is capable of mobilising significant amounts of Fe. This process could have produced, in part or totally, the Fe deposits located close to the quartz–tourmaline veins and metasomatic bodies of the Mt. Calamita Formation. Moreover, the super-hot reservoir that likely occurs in the deepest part of the Larderello–Travale geothermal field would also be the site of an extensive reaction between the B-rich fluid and biotite-bearing rocks producing tourmaline. Thus, tourmaline occurrence can be a useful guide during deep

Multiscale Simulation of Gas Film Lubrication During Liquid Droplet Collision

Science.gov (United States)

Chen, Xiaodong; Khare, Prashant; Ma, Dongjun; Yang, Vigor

2012-02-01

Droplet collision plays an elementary role in dense spray combustion process. When two droplets approach each other, a gas film forms in between. The pressure generated within the film prevents motion of approaching droplets. This fluid mechanics is fluid film lubrication that occurs when opposing bearing surfaces are completely separated by fluid film. The lubrication flow in gas film decides the collision outcome, coalescence or bouncing. Present study focuses on gas film drainage process over a wide range of Weber numbers during equal- and unequal-sized droplet collision. The formulation is based on complete set of conservation equations for both liquid and surrounding gas phases. An improved volume-of-fluid technique, augmented by an adaptive mesh refinement algorithm, is used to track liquid/gas interfaces. A unique thickness-based refinement algorithm based on topology of interfacial flow is developed and implemented to efficiently resolve the multiscale problem. The grid size on interface is up O(10-4) of droplet size with a max resolution of 0.015 μm. An advanced visualization technique using the Ray-tracing methodology is used to gain direct insights to detailed physics. Theories are established by analyzing the characteristics of shape changing and flow evolution.

Experimental Analysis of Damping and Tribological Characteristics of Nano-CuO Particle Mixed Lubricant in Ball Bearings

Science.gov (United States)

Prakash, E.; Sivakumar, K.

2015-12-01

Experimental analysis of damping capacity and tribological characteristics of nano CuO added Servosystem 68 lubricant is attempted. CuO nano particles were synthesized by aqueous precipitation method and characterized. Prior to dispersion into lubricant, CuO nano particles were coated with 0.2 wt.% surfactant (Span-80) to stabilize the nano fluid. Tribological characteristics of particle added lubricant were tested in ASTM D 4172 four ball wear tester. Scanning electron microscopy test results of worn surfaces of nano CuO particle added lubricant were smoother than base lubricant. The particle added lubricant was applied in a new ball bearing and three defected ball bearings. When particle added lubricant was used, the ball defected bearing's vibration amplitude was reduced by 21.94% whereas it was 16.46% for new bearing and was ≤ 11% for other defected bearings. The formation of protection film of CuO over ball surface and regime of full film lubrication near the ball zone were observed to be reason for improved damping of vibrations.

Design and modeling of semi-active squeeze film dampers using magneto-rheological fluids

International Nuclear Information System (INIS)

Kim, Keun-Joo; Lee, Chong-Won; Koo, Jeong-Hoi

2008-01-01

Conventional squeeze film dampers (SFDs) have shown their effectiveness in suppressing unbalanced vibrations in rotor systems, particularly supported by rolling element bearings. Recently, there is an increasing demand for 'controllable' SFDs to meet the need of modern rotating machinery, characterized by high operating speed and high load capacity. Thus, this paper presents a controllable semi-active SFD using magneto-rheological (MR) fluids, focusing on its design and modeling. It offers a comprehensive design method and an innovative experimental identification and modeling technique for MR-SFDs. The primary goal of the MR-SFD design is set to maximize its dynamic control bandwidth, and the design method includes the material selection, magnetic circuit analysis and sealing element design. After constructing a prototype MR-SFD based on the final design, this work investigated how some of the critical design parameters affect the performance of the MR-SFD (i.e. its dynamic control bandwidth change). Furthermore, it characterized the damper's dynamic behavior experimentally using a novel excitation method that adopts active magnetic bearing (AMB) units. Unlike conventional methods, the AMB system was able to precisely control the amplitude and frequency of the input excitation, enabling us to obtain the nonlinear dynamic stiffness properties of the MR-SFD with varying input current. In modeling the dynamic behavior of the MR-SFD, this study employed the describing function method. The describing function analysis effectively captured the nonlinear dynamic behavior of the MR-SFD

Rotordynamics of automotive turbochargers. Linear and nonlinear rotordynamics - Bearing design - Rotor balancing

Energy Technology Data Exchange (ETDEWEB)

Nguyen-Schaefer, Hung [Bosch Mahle Turbo Systems GmbH und Co. KG, Stuttgart (Germany)

2012-11-01

Describes the rotordynamics of automotive turbochargers. Requires only a minimum of mathematical background. Written by an R and D expert from industry. This book deals with rotordynamics of automotive turbochargers while encompassing the analysis of the dynamics of rotating machines at very high rotor speeds of 300,000 rpm and above. This interdisciplinary field involves 1. thermodynamics and turbo-matching knowledge to compute working conditions of turbochargers, 2. fluid and bearing dynamics to calculate various operating thrust loads and to design the rotating floating ring bearings (two-oil-film bearings), and 3. tribology to improve the rotor stability and to reduce the bearing friction. Mathematical background in modeling and simulation methods is necessary; however, the prerequisites have been kept to a minimum. The book addresses both practitioners working in the field of rotordynamics of automotive turbochargers and graduate students in mechanical engineering.

Dynamical Simulations of a Flexible Rotor in Cylindrical Uncavitated and Cavitated Lubricated Journal Bearings

Directory of Open Access Journals (Sweden)

Alessandro Ruggiero

2018-04-01

Full Text Available Due to requirements of their operating conditions, such as high speed, high flexibility and high efficiency, rotating machines are designed to obtain larger operating ranges. These operating conditions can increase the risk of fluid-induced instability. In fact, the presence of non-linear fluid forces when the threshold speed is overcome by the rotational speed, can generate rotor lateral self-excited vibrations known as “oil whirl” or “oil whip”. These instabilities derive from the interaction between the rotor and the sliding bearing and they are typically sub-synchronous and they contribute to eventual rubbing between rotor and stator with consequent damage to the rotating machines. For these reasons, the aim of this paper is to numerically investigate the differences in the dynamic behaviour of a flexible rotor supported by cylindrical lubricated journal bearings. The study considers two different cases, uncavitated and cavitated lubricated films, in order to develop an original Matlab-Simulink algorithm for the numerical solution of the differential non-linear equations of motion of the unbalanced flexible rotor supported on hydrodynamic journal bearings. The bearings were modelled as uncavitated and cavitated (π-Film short bearings derived from classical Reynolds’ theory. Dynamic simulation allowed prediction of the shape and size of the orbit performed by the system and evaluation of the vibrating phenomena exerted by the rotor during the motion. The results show that cavitation completely modifies the behaviour of the system in every aspect. The analysis of the diagrams obtained showed that the proposed algorithm provides consistent results and represents a valuable instrument for dynamic analysis of rotating systems.

Nonlinear Dynamics of a Foil Bearing Supported Rotor System: Simulation and Analysis

Science.gov (United States)

Li, Feng; Flowers, George T.

1996-01-01

Foil bearings provide noncontacting rotor support through a number of thin metal strips attached around the circumference of a stator and separated from the rotor by a fluid film. The resulting support stiffness is dominated by the characteristics of the foils and is a nonlinear function of the rotor deflection. The present study is concerned with characterizing this nonlinear effect and investigating its influence on rotordynamical behavior. A finite element model is developed for an existing bearing, the force versus deflection relation characterized, and the dynamics of a sample rotor system are studied. Some conclusions are discussed with regard to appropriate ranges of operation for such a system.

Active Lubrication for Reducing Wear and Vibration: A combination of Fluid Power Control and Tribology

DEFF Research Database (Denmark)

Nicoletti, Rodrigo; Santos, Ilmar

2002-01-01

The use of fluid power to reduce and control rotor vibration in rotating machines is investigated. An active hybrid bearing is studied, whose main objective is to reduce wear and vibration between rotating and stationary machinery parts. By injecting pressurised oil into the oil film, through...... orifices machined in the bearing pads, one can alter the machine dynamic characteristics, thus enhancing its operational range. A mathematical model of the rotor-bearing system, as well as of the hydraulic system, is presented. Numerical results of the system frequency response show good agreement...

Supercritical fluid molecular spray thin films and fine powders

Science.gov (United States)

Smith, Richard D.

1988-01-01

Solid films are deposited, or fine powders formed, by dissolving a solid material into a supercritical fluid solution at an elevated pressure and then rapidly expanding the solution through a short orifice into a region of relatively low pressure. This produces a molecular spray which is directed against a substrate to deposit a solid thin film thereon, or discharged into a collection chamber to collect a fine powder. The solvent is vaporized and pumped away. Solution pressure is varied to determine, together with flow rate, the rate of deposition and to control in part whether a film or powder is produced and the granularity of each. Solution temperature is varied in relation to formation of a two-phase system during expansion to control porosity of the film or powder. A wide variety of film textures and powder shapes are produced of both organic and inorganic compounds. Films are produced with regular textural feature dimensions of 1.0-2.0 .mu.m down to a range of 0.01 to 0.1 .mu.m. Powders are formed in very narrow size distributions, with average sizes in the range of 0.02 to 5 .mu.m.

The effect of lubricating oils on bearing fatigue-life using the Evonik RohMax pitting test procedure

Energy Technology Data Exchange (ETDEWEB)

Bartels, Thorsten [Evonik RohMax Additives GmbH, Darmstadt (Germany)

2009-07-01

A major requirement for modern driveline lubricants is the need to reduce churning losses and friction in order to deliver continual improvements in fuel efficiency. In trying to achieve this oil formulators target lower and lower viscosities, testing the limits of what is acceptable Churning loss reductions are being made by reducing the viscosity of the lubricating oil. Reduced oil viscosities can lead to reduced oil film thicknesses, especially at high operating temperatures. Thinner oil films can lead to an increase in friction, and a decrease in the fatigue-life capacity in lubricated contacts of bearings and gears in several driveline applications. Extensive fluid testing is required. Current test procedures are subject to extremely high variability, and large numbers of experiments are required to develop high confidence in the test conclusions. This publication introduces a new fatigue-life test method, which in our hands provides a clear improvement in test time, cost, and reproducibility. The test's results enable an estimation of the effect of lubricating oils on bearing fatigue-life. This is done by comparing the results to those obtained with reference oils which have also been tested in the standardized bearing tests for lubricating oils. The effects of operating parameters on test accuracy and repeatability have been studied. The parameters studied are oil temperature, contact pressure, speed and the test specimen batch. In addition to the measurement of bearing fatigue-life, the new test may also be used to study gear fatigue-life. We have used this test to investigate the lubrication oils' influence on fatigue-life in bearings and in gears. In order to extend the comparisons to gear performance the reference fluids were evaluated in standard industry test procedures used for determining gear performance, in particular the FZG test rig, thus establishing an extra insight in the fluids' performance by comparing gear test performance

Parametric studies on floating pad journal bearing for high speed cryogenic turboexpanders

Science.gov (United States)

Jain, A.; Jadhav, M. M.; Karimulla, S.; Chakravarty, A.

2017-12-01

Most modern medium and large capacity helium liquefaction/refrigeration plants employ high speed cryogenic turboexpanders in their refrigeration/liquefaction cycles as active cooling devices. The operating speed of these turboexpanders is in the range of 3000-5000 Hz and hence specialized types of bearings are required. Floating pad journal bearing, which is a special type of tilting pad journal bearing, where mechanical pivots are absent and pads are fully suspended in gas, can be a good solution for stable operation of these high speed compact rotors. The pads are separated from shaft as well as from housing by fluid film between them, and both these sides of pad are interconnected by a network of feed holes. The work presented in this article aims to characterize floating pad journal bearings through parametric studies. The steady state performance characteristics of the bearing are represented by load capacity, stiffness coefficients and heat generation rate of the bearing. The geometrical parameters such as bearing clearances, preload of pads, etc. are varied and performance characteristics of the floating pad journal bearing are studied and presented. The dependence of stiffness coefficients on rotational speed of shaft is also analyzed.

Study on Nonlinear Vibration and Crack Fault of Rotor-bearing-seal Coupling System

Directory of Open Access Journals (Sweden)

Yuegang LUO

2014-02-01

Full Text Available The nonlinear dynamic model of rotor-bearing-seal system with crack in shaft is set up based on the coupling model of nonlinear oil-film force and Muszyska’s nonlinear seal fluid force. The dynamic vibration characteristics of the rotor-bearing-seal system and the effects of physical and structural parameters of labyrinth seal and crack fault on movement character of the rotor were analyzed. The increases of seal length, seal pressure differential, seal radius and axial velocity are in favor of the stability of the system, and it of seal gap and crack depth are not in favor of the stability of the system.

Fluid instabilities and wakes in a soap-film tunnel

International Nuclear Information System (INIS)

Vorobieff, P.; Ecke, R.E.

1999-01-01

We present a compact, low-budget two-dimensional hydrodynamic flow visualization system based on a tilted, gravity-driven soap film tunnel. This system is suitable for demonstrations and studies of a variety of fluid mechanics problems, including turbulent wakes past bluff bodies and lifting surfaces, Kelvin - Helmholtz instability, and grid turbulence. copyright 1999 American Association of Physics Teachers

Field Tests on Hydrodynamic and Hybrid Operation of a Bidirectional Thrust Bearing of a Pump-Turbine

Directory of Open Access Journals (Sweden)

Michał Wasilczuk

2017-12-01

Full Text Available In vertical shaft pump turbines operating in pumped storage power plants an important role is played by a thrust bearing. Due to the bidirectional character of operation, thrust bearing tilting pads have to be supported symmetrically, which is known to be unfavourable from the point of view of their performance. Large thrust bearings have to be carefully designed so as to minimise excessive thermo-elastic pad deformations. The research into fluid film thrust bearings has been quite extensive over the years, comprising theoretical studies of bearing properties with the use of more and more sophisticated calculation codes. On the other hand, the availability of experimental field data on bearing operation is limited, for obvious reasons. In this paper the authors present part of the results of extensive field tests of a large bearing of a pump-turbine they have conducted in a pumped storage power plant. Hopefully this data will be of interest to other researchers to compare theoretical predictions to measurement data.

Validation of film dryout model in a three-fluid code FIDAS

International Nuclear Information System (INIS)

Sugawara, Satoru

1989-11-01

Analytical prediction model of critical heat flux (CHF) has been developed on the basis of film dryout criterion due to droplets deposition and entrainment in annular mist flow. CHF in round tubes were analyzed by the Film Dryout Analysis Code in Subchannels, FIDAS, which is based on the three-fluid, three-field and newly developed film dryout model. Predictions by FIDAS were compared with the world-wide experimental data on CHF obtained in water and Freon for uniformly and non-uniformly heated tubes under vertical upward flow condition. Furthermore, CHF prediction capability of FIDAS was compared with those of other film dryout models for annular flow and Katto's CHF correlation. The predictions of FIDAS are in sufficient agreement with the experimental CHF data, and indicate better agreement than the other film dryout models and empirical correlation of Katto. (author)

Development of an aerostatic bearing system for roll-to-roll printed electronics

Science.gov (United States)

Chen, Shasha; Chen, Weihai; Liu, Jingmeng; Chen, Wenjie; Jin, Yan

2018-06-01

Roll-to-roll printed electronics is proved to be an effective way to fabricate electrical devices on various substrates. High precision overlay alignment plays a key role to create multi-layer electrical devices. Multiple rollers are adopted to support and transport the substrate web. In order to eliminate the negative effect of the machining error and assembling error of the roller, a whole roll-to-roll system including two aerostatic bearing devices with arrayed restrictors is proposed in this paper. Different to the conventional roller, the aerostatic bearing device can create a layer of air film between the web and the device to realize non-contact support and transport. Based on simplified Navier–Stokes equations, the theoretical model of the air film is established. Moreover, the pressure distribution of the whole flow field and single restrictor in different positions are modeled by conducting numerical simulation with computational fluid dynamics (CFD) software FLUENT. The load capacity curves and stiffness curves are generated to provide guidance for optimizing the structure of the device. A prototype of the aerostatic bearing system is set up and the experiment tests are carried out. For the proposed aerostatic bearing roller with a diameter of 100 mm and length of 200 mm, the experimental results show the aerostatic bearing method can achieve the position accuracy in a range of 1 μm in the vertical direction of the web, which is much better than that using existing methods.

Diagnosis at a glance of biological non-Newtonian fluids with Film Interference Flow Imaging (FIFI)

Science.gov (United States)

Hidema, R.; Yamada, N.; Furukawa, H.

2012-04-01

In the human body, full of biological non-Newtonian fluids exist. For example, synovial fluids exist in our joints, which contain full of biopolymers, such as hyaluronan and mucin. It is thought that these polymers play critical roles on the smooth motion of the joint. Indeed, luck of biopolymers in synovial fluid cause joint pain. Here we study the effects of polymer in thin liquid layer by using an original experimental method called Film Interference Flow Imaging (FIFI). A vertically flowing soap film containing polymers is made as two-dimensional flow to observe turbulence. The thickness of water layer is about 4 μm sandwiched between surfactant mono-layers. The interference pattern of the soap film is linearly related to the flow velocity in the water layer through the change in the thickness of the film. Thus the flow velocity is possibly analyzed by the single image analysis of the interference pattern, that is, FIFI. The grid turbulence was made in the flowing soap films containing the long flexible polymer polyethyleneoxide (PEO, Mw=3.5x106), and rigid polymer hydroxypropyl cellulose (HPC, Mw > 1.0 x106). The decaying process of the turbulence is affected by PEO and HPC at several concentrations. The effects of PEO are sharply seen even at low concentrations, while the effects of HPC are gradually occurred at much higher concentration compared to the PEO. It is assumed that such a difference between PEO and HPC is due to the polymer stretching or polymer orientation under turbulence, which is observed and analyzed by FIFI. We believe the FIFI will be applied in the future to examine biological fluids such as synovial fluids quickly and quantitatively.

Pressure and density measurements of selected fluid-bearing zones at the Waste Isolation Pilot Plant (WIPP)

International Nuclear Information System (INIS)

Winstanley, D.; Carrasco, R.; Zurkoff, J.

1986-01-01

A field effort is presently being conducted at the Waste Isolation Pilot Plant (WIPP) to collect accurate pressure and density information from the Culebra and Magenta dolomite members of the Rustler formation. The spatial variation of fluid density that occurs in these water-bearing units requires the use of numerical models to accurately solve for flow direction and velocity. The groundwater regime is a vital element in possible release scenarios of radionuclide-bearing fluid from the repository. Field tests were conducted on four wells utilizing a testing apparatus composed of two pressure and temperature monitoring systems and a point water sampler. Pressure versus depth plots are linear with a correlation coefficient of 0.999 or greater. Comparison of the calculated density and measured density of water obtained at depth agree within 2 percent of density measurements obtained after continuous pumping of the formation for several days before sampling. The temperature gradients ranged from 0.4 0 to 0.6 0 C per 100 feet. The data presented here are preliminary and serve as developmental information for the detailed operating plan currently under preparation

Evaluation of ion-sputtered molybdenum disulfide bearings for spacecraft gimbals

Science.gov (United States)

Loewenthal, S. H.; Chou, R. G.; Hopple, G. B.; Wenger, W. L.

1994-07-01

High-density, sputtered molybdenum disulfide films (MoS2) were investigated as lubricants for the next generation of spacecraft gimbal bearings where low torque signatures and long life are required. Low friction in a vacuum environment, virturally no out-gassing, insensitivity to low temperature, and radiation resistance of these lubricant films are valued in such applications. One hundred and twenty five thousand hours of acumulated bearing test time were obtained on 24 pairs of flight-quality bearings ion-sputtered with three types of advanced MoS2 films. Life tests were conducted in a vacuum over a simulated duty cycle for a space payload gimbal. Optimum retainer and ball material composition were investigated. Comparisions were made with test bearings lubricated with liquid space lubricants. Self-lubricating PTFE retainers were required for long life, i.e., greater than 40 million gimbal cycles. Bearings with polyimide retainers, silicon nitride ceramic balls, or steel balls sputtered with MoS2 film suffered early torque failure, irrespective of the type of race-sputtered MoS2 film. Failure generally resulted from excess film or retainer debris deposited in the ball track which tended to jam the bearing. Both grease lubricated and the better MoS2 film lubricated bearings produced long lives, although the torque with liquid lubricants was lower and less irregular.

The R and D D`s bearing test benches; Les bancs d`essais de paliers de la DER

Energy Technology Data Exchange (ETDEWEB)

Vialettes, J.M. [Service Ensembles de Production, Departement Machines, Direction des Etudes et Recherches, Electricite de France (EDF), 92 - Clamart (France)

1997-01-01

In power generation plants, rotating machines are involved in energy transformation processes and safety systems. The bearings supporting the rotors and the thrust bearings play a crucial role in the reliability of these machines. The phenomena encountered straddle several disciplines: hydrodynamics, tribology, thermomechanics, materials and vibrations in a specific environment, namely: thin fluid film, solid mechanical components and shaft rotation. Means of analysing the behaviour of these components (bearings and thrust bearings) have been developed and implemented. These consists of the EDYOS (Etude Dynamique des Organes de Supportage) code for dynamically studying bearing devices and several related bench tests. In reality, in order to understand the complex physical phenomena encountered in these components, it is vital to carry out analyses and experimental validations. Since these investigations cannot be carried out on actual machines, test benches have been built which can subject the sample bearings to the equivalent stresses. (author) 14 figs.

Polyethylene glycol drilling fluid for drilling in marine gas hydrates-bearing sediments: an experimental study

Energy Technology Data Exchange (ETDEWEB)

Jiang, G.; Liu, T.; Ning, F.; Tu, Y.; Zhang, L.; Yu, Y.; Kuang, L. [China University of Geosciences, Faculty of Engineering, Wuhan (China)

2011-07-01

Shale inhibition, low-temperature performance, the ability to prevent calcium and magnesium-ion pollution, and hydrate inhibition of polyethylene glycol drilling fluid were each tested with conventional drilling-fluid test equipment and an experimental gas-hydrate integrated simulation system developed by our laboratory. The results of these tests show that drilling fluid with a formulation of artificial seawater, 3% bentonite, 0.3% Na{sub 2}CO{sub 3}, 10% polyethylene glycol, 20% NaCl, 4% SMP-2, 1% LV-PAC, 0.5% NaOH and 1% PVP K-90 performs well in shale swelling and gas hydrate inhibition. It also shows satisfactory rheological properties and lubrication at temperature ranges from -8 {sup o}C to 15 {sup o}C. The PVP K-90, a kinetic hydrate inhibitor, can effectively inhibit gas hydrate aggregations at a dose of 1 wt%. This finding demonstrates that a drilling fluid with a high addition of NaCl and a low addition of PVP K-90 is suitable for drilling in natural marine gas-hydrate-bearing sediments. (authors)

Polyethylene Glycol Drilling Fluid for Drilling in Marine Gas Hydrates-Bearing Sediments: An Experimental Study

Directory of Open Access Journals (Sweden)

Lixin Kuang

2011-01-01

Full Text Available Shale inhibition, low-temperature performance, the ability to prevent calcium and magnesium-ion pollution, and hydrate inhibition of polyethylene glycol drilling fluid were each tested with conventional drilling-fluid test equipment and an experimental gas-hydrate integrated simulation system developed by our laboratory. The results of these tests show that drilling fluid with a formulation of artificial seawater, 3% bentonite, 0.3% Na2CO3, 10% polyethylene glycol, 20% NaCl, 4% SMP-2, 1% LV-PAC, 0.5% NaOH and 1% PVP K-90 performs well in shale swelling and gas hydrate inhibition. It also shows satisfactory rheological properties and lubrication at temperature ranges from −8 °C to 15 °C. The PVP K-90, a kinetic hydrate inhibitor, can effectively inhibit gas hydrate aggregations at a dose of 1 wt%. This finding demonstrates that a drilling fluid with a high addition of NaCl and a low addition of PVP K-90 is suitable for drilling in natural marine gas-hydrate-bearing sediments.

Improvement of journal bearing operation at heavy misalignment using bearing flexibility and compliant liners

DEFF Research Database (Denmark)

Thomsen, Kim; Klit, Peder

2012-01-01

A flexure journal bearing design is proposed that will improve operational behaviour of a journal bearing at pronounced misalignment. Using a thermoelastohydrodynamic model, it is shown that the proposed flexure journal bearing has vastly increased the hydrodynamic performance compared to the stiff...... bearing when misaligned. The hydrodynamic performance is evaluated on lubricant film thickness, pressure and temperature. Furthermore, the influence of a compliant bearing liner is investigated and it is found that it increases the hydrodynamic performance when applied to a stiff bearing, whereas...... the liner has practically no influence on the flexure journal bearing's performance....

On the computation of electrical resistance of hydrodynamic journal bearing

Directory of Open Access Journals (Sweden)

Eleonora Pop

2014-12-01

Full Text Available The paper approaches the mathematical model of electrical resistance of hydrodynamic journal bearing under different parameters of operation so as to predict bearing performance and safe load carrying capacity. The currents circulating in the journal bearing of electrical machine causes reducing of lifespan by appearance of pitting on their surface and the degradation of the lubricant. In a hydrodynamic journal bearing, the zone of minimum film thickness, load-carrying oil film varies along the circumference of a bearing through its length. This has been found to form a capacitor of varying capacitance between the journal and the bearings dependent on permittivity of the lubricant used, the bearing length, the eccentricity ratio and the clearance ratio. Besides this, load-carrying on oil film offers resistance that depends on operating parameters and resistivity of the lubricant.

Proteins at fluid interfaces: adsorption layers and thin liquid films.

Science.gov (United States)

Yampolskaya, Galina; Platikanov, Dimo

2006-12-21

A review in which many original published results of the authors as well as many other papers are discussed. The structure and some properties of the globular proteins are shortly presented, special accent being put on the alpha-chymotrypsin (alpha-ChT), lysozyme (LZ), human serum albumin (HSA), and bovine serum albumin (BSA) which have been used in the experiments with thin liquid films. The behaviour of protein adsorption layers (PAL) is extensively discussed. The dynamics of PAL formation, including the kinetics of adsorption as well as the time evolution of the surface tension of protein aqueous solutions, are considered. A considerable place is devoted to the surface tension and adsorption isotherms of the globular protein solutions, the simulation of PAL by interacting hard spheres, the experimental surface tension isotherms of the above mentioned proteins, and the interfacial tension isotherms for the protein aqueous solution/oil interface. The rheological properties of PAL at fluid interfaces are shortly reviewed. After a brief information about the experimental methods for investigation of protein thin liquid (foam or emulsion) films, the properties of the protein black foam films are extensively discussed: the conditions for their formation, the influence of the electrolytes and pH on the film type and stability, the thermodynamic properties of the black foam films, the contact angles film/bulk and their dynamic hysteresis. The next center of attention concerns some properties of the protein emulsion films: the conditions for formation of emulsion black films, the formation and development of a dimpling in microscopic, circular films. The protein-phospholipid mixed foam films are also briefly considered.

Analysis of Hard Thin Film Coating

Science.gov (United States)

Shen, Dashen

1998-01-01

MSFC is interested in developing hard thin film coating for bearings. The wearing of the bearing is an important problem for space flight engine. Hard thin film coating can drastically improve the surface of the bearing and improve the wear-endurance of the bearing. However, many fundamental problems in surface physics, plasma deposition, etc, need further research. The approach is using electron cyclotron resonance chemical vapor deposition (ECRCVD) to deposit hard thin film an stainless steel bearing. The thin films in consideration include SiC, SiN and other materials. An ECRCVD deposition system is being assembled at MSFC.

Refrigerant falling film evaporation review: Description, fluid dynamics and heat transfer

International Nuclear Information System (INIS)

Fernández-Seara, José; Pardiñas, Ángel Á.

2014-01-01

Falling film horizontal tube evaporators for refrigeration equipment are an interesting alternative to pool boiling evaporators concerning operation costs, safety, thermodynamic efficiency, charge of refrigerant or size. Plenty of literature works studied falling film evaporation, but for its application in fields such as desalination and petrochemical industry or OTEC. This review focuses mainly on those works from the literature that analysed the main issues of falling film evaporation of refrigerants, to better understand heat transfer and fluid dynamics in such evaporators. First, falling film evaporation is described and compared to pool boiling, to define its main advantages and inconveniences. Then, the literature concerning film around the tubes and between them is analysed, as well as the phenomenon of film breakdown, which sharply deteriorates the heat transfer performance of falling film evaporators. After it, the results from those works that studied analytically and experimentally the heat transfer coefficients (HTCs) with different types of tubes and refrigerants are discussed. The review finishes with a brief summary of important parameters of falling film evaporation, which might be useful for the design of such equipment. - Highlights: •We defined falling film evaporation and compared it with pool boiling. •We reviewed works from the literature concerning refrigerant falling film evaporation. •We classified the ideas from the works attending to crucial aspects of the process. •We developed a summary of the main ideas which could be useful for design purpose

Supercritical fluid molecular spray film deposition and powder formation

Science.gov (United States)

Smith, Richard D.

1986-01-01

Solid films are deposited, or fine powders formed, by dissolving a solid material into a supercritical fluid solution at an elevated pressure and then rapidly expanding the solution through a short orifice into a region of relatively low pressure. This produces a molecular spray which is directed against a substrate to deposit a solid thin film thereon, or discharged into a collection chamber to collect a fine powder. Upon expansion and supersonic interaction with background gases in the low pressure region, any clusters of solvent are broken up and the solvent is vaporized and pumped away. Solute concentration in the solution is varied primarily by varying solution pressure to determine, together with flow rate, the rate of deposition and to control in part whether a film or powder is produced and the granularity of each. Solvent clustering and solute nucleation are controlled by manipulating the rate of expansion of the solution and the pressure of the lower pressure region. Solution and low pressure region temperatures are also controlled.

Mueller-matrix of laser-induced autofluorescence of polycrystalline films of dried peritoneal fluid in diagnostics of endometriosis

Science.gov (United States)

Ushenko, Yuriy A.; Koval, Galina D.; Ushenko, Alexander G.; Dubolazov, Olexander V.; Ushenko, Vladimir A.; Novakovskaia, Olga Yu.

2016-07-01

This research presents investigation results of the diagnostic efficiency of an azimuthally stable Mueller-matrix method of analysis of laser autofluorescence of polycrystalline films of dried uterine cavity peritoneal fluid. A model of the generalized optical anisotropy of films of dried peritoneal fluid is proposed in order to define the processes of laser autofluorescence. The influence of complex mechanisms of both phase (linear and circular birefringence) and amplitude (linear and circular dichroism) anisotropies is taken into consideration. The interconnections between the azimuthally stable Mueller-matrix elements characterizing laser autofluorescence and different mechanisms of optical anisotropy are determined. The statistical analysis of coordinate distributions of such Mueller-matrix rotation invariants is proposed. Thereupon the quantitative criteria (statistic moments of the first to the fourth order) of differentiation of polycrystalline films of dried peritoneal fluid, group 1 (healthy donors) and group 2 (uterus endometriosis patients), are determined.

Quartz-Amethyst Hosted Hydrocarbon-Bearing Fluid Inclusions from the Green Ridge Breccia in the Snoqualmie Granite, North Cascades, WA, USA

Directory of Open Access Journals (Sweden)

Martin Feely

2017-09-01

Full Text Available The Green Ridge Breccia cuts the composite Miocene Snoqualmie Batholith in King County, WA, USA. The granite was emplaced at ~5 km depth between ~17 and 20 Ma and the crosscutting NW trending breccia contains large angular blocks of the host granite (<1 m in longest dimension. The brecciated granite blocks are cemented by quartz-amethyst euhedra (<10 cm in longest dimension bearing vugs. A notable feature is the presence of centimetric scale amber coloured oil inclusions within the quartz-amethyst crystals. Fluid inclusion studies using Transmitted Light Petrography, UV Microscopy, Microthermometry, Laser Raman Microspectroscopy and Gas Chromatography-Mass Spectrometry record the presence and the fluid composition of three fluid inclusion types hosted by the euhedra: primary Type 1 (liquid rich two-phase (L + V aqueous inclusions and secondary Type 2 bituminous two-phase (S + L inclusions and Type 3 amber coloured oil bearing two-phase immiscible liquid inclusions. The Green Ridge Breccia was the locus for convective hydrothermal fluid flow that formed the quartz-amethyst vugs formed at T~390 °C assuming a trapping pressure of ~1.65 kb. Later, hydrocarbon fluids migrated downwards from the roof source rock (e.g., the Guye Sedimentary Member and were trapped in the euhedra. This was followed by unroofing of the batholith and exposure of the Green Ridge Breccia. This study highlights the potential for other oil migrations into the Snoqualmie Batholith in areas where it forms the basement capped by the Guye Sedimentary Member.

Distortion of liquid film discharging from twin-fluid atomizer

Science.gov (United States)

Mehring, C.; Sirignano, W. A.

2001-11-01

The nonlinear distortion and disintegration of a thin liquid film exiting from a two-dimensional twin-fluid atomizer is analyzed numerically. Pulsed gas jets impacting on both sides of the discharging liquid film at the atomizer exit generate dilational and/or sinuous deformations of the film. Both liquid phase and gas phase are inviscid and incompressible. For the liquid phase the so-called long-wavelength approximation is employed yielding a system of unsteady one-dimensional equations for the planar film. Solution of Laplace's equation for the velocity potential yields the gas-phase velocity field on both sides of the liquid stream. Coupling between both phases is described through kinematic and dynamic boundary conditions at the phase interfaces, and includes the solution of the unsteady Bernoulli equation to determine the gas-phase pressure along the interfaces. Both gas- and liquid-phase equations are solved simultaneously. Solution of Laplace's equation for the gas streams is obtained by means of a boundary-element method. Numerical solutions for the liquid phase use the Lax-Wendroff method with Richtmyer splitting. Sheet distortion resulting from the stagnation pressure of the impacting gas jets and subsequent disturbance amplification due to Kelvin-Helmholtz effects are studied for various combinations of gas-pulse timing, gas-jet impact angles, gas-to-liquid-density ratio, liquid-phase Weber number and gas-jet-to-liquid-jet-momentum ratio. Dilational and sinuous oscillations of the liquid are examined and film pinch-off is predicted.

Estimation of Dry Fracture Weakness, Porosity, and Fluid Modulus Using Observable Seismic Reflection Data in a Gas-Bearing Reservoir

Science.gov (United States)

Chen, Huaizhen; Zhang, Guangzhi

2017-05-01

Fracture detection and fluid identification are important tasks for a fractured reservoir characterization. Our goal is to demonstrate a direct approach to utilize azimuthal seismic data to estimate fluid bulk modulus, porosity, and dry fracture weaknesses, which decreases the uncertainty of fluid identification. Combining Gassmann's (Vier. der Natur. Gesellschaft Zürich 96:1-23, 1951) equations and linear-slip model, we first establish new simplified expressions of stiffness parameters for a gas-bearing saturated fractured rock with low porosity and small fracture density, and then we derive a novel PP-wave reflection coefficient in terms of dry background rock properties (P-wave and S-wave moduli, and density), fracture (dry fracture weaknesses), porosity, and fluid (fluid bulk modulus). A Bayesian Markov chain Monte Carlo nonlinear inversion method is proposed to estimate fluid bulk modulus, porosity, and fracture weaknesses directly from azimuthal seismic data. The inversion method yields reasonable estimates in the case of synthetic data containing a moderate noise and stable results on real data.

Bearing assemblies, apparatuses, and motor assemblies using the same

Science.gov (United States)

Sexton, Timothy N.; Cooley, Craig H.; Knuteson, Cody W.

2015-12-29

Various embodiments of the invention relate to bearing assemblies, apparatuses and motor assemblies that include geometric features configured to impart a selected amount of heat transfer and/or hydrodynamic film formation. In an embodiment, a bearing assembly may include a plurality of superhard bearing pads distributed circumferentially about an axis. At least some of the plurality of superhard bearing pads may include a plurality of sub-superhard bearing elements defining a bearing surface. At least some of the plurality of sub-superhard bearing elements may be spaced from one another by one or more voids to impart a selected amount of heat transfer and hydrodynamic film formation thereon during operation. The bearing assembly may also include a support ring that carries the plurality of superhard bearing pads. In addition, at least a portion of the sub-superhard bearing elements may extend beyond the support ring.

Testing of bearing materials for large two-stroke marine diesel engines

DEFF Research Database (Denmark)

Vølund, Anders; Klit, Peder; Persson, Sebastian

2017-01-01

In large two-stroke marine diesel engines, bearings are designed to last the lifetime of the engine. The design has shown very good service experiences. The design parameters of the main bearings are, among others, based on the average maximum specific load which the bearing should operate under....... In general, the frictional loss is less than 1% of the nominal power of the engine but is still a target for optimization. Fatigue mechanisms of bearing lining material are not fully understood and the design limits with regards to minimum oil film thickness, max oil film pressure and oil film pressure...

Performance of two-lobe hole-entry hybrid journal bearing system under the combined influence of textured surface and couple stress lubricant

Science.gov (United States)

Khatri, Chandra B.; Sharma, Satish C.

2018-02-01

Textured surface in journal bearings is becoming an important area of investigation during the last few years. Surface textures have the shapes of micro-dimple with a small diameter and depth having order of magnitude of bearing clearance. This paper presents the influence of couple stress lubricant on the circular and non-circular hole-entry hybrid journal bearing system and reports the comparative study between the textured and non-textured circular/non-circular hybrid journal bearing system. The governing Reynolds equation has been modified for the couple stress lubricant flow in the clearance of bearing and journal. The FEM technique has been applied to solve the modified Reynolds equation together with restrictor flow equation. The numerically simulated results indicate that the influence of couple stress lubricant is significantly more in textured journal bearing than that of non-textured journal bearing. Further, it has been observed that the textured two-lobe (δ = 1.1) hybrid journal bearing lubricated with couple stress lubricant provides larger values of fluid film stiffness coefficients and stability threshold speed against other bearings studied in the present paper.

Alteration of fault rocks by CO2-bearing fluids with implications for sequestration

Science.gov (United States)

Luetkemeyer, P. B.; Kirschner, D. L.; Solum, J. G.; Naruk, S.

2011-12-01

Carbonates and sulfates commonly occur as primary (diagenetic) pore cements and secondary fluid-mobilized veins within fault zones. Stable isotope analyses of calcite, formation fluid, and fault zone fluids can help elucidate the carbon sources and the extent of fluid-rock interaction within a particular reservoir. Introduction of CO2 bearing fluids into a reservoir/fault system can profoundly affect the overall fluid chemistry of the reservoir/fault system and may lead to the enhancement or degradation of porosity within the fault zone. The extent of precipitation and/or dissolution of minerals within a fault zone can ultimately influence the sealing properties of a fault. The Colorado Plateau contains a number of large carbon dioxide reservoirs some of which leak and some of which do not. Several normal faults within the Paradox Basin (SE Utah) dissect the Green River anticline giving rise to a series of footwall reservoirs with fault-dependent columns. Numerous CO2-charged springs and geysers are associated with these faults. This study seeks to identify regional sources and subsurface migration of CO2 to these reservoirs and the effect(s) faults have on trap performance. Data provided in this study include mineralogical, elemental, and stable isotope data for fault rocks, host rocks, and carbonate veins that come from two localities along one fault that locally sealed CO2. This fault is just tens of meters away from another normal fault that has leaked CO2-charged waters to the land surface for thousands of years. These analyses have been used to determine the source of carbon isotopes from sedimentary derived carbon and deeply sourced CO2. XRF and XRD data taken from several transects across the normal faults are consistent with mechanical mixing and fluid-assisted mass transfer processes within the fault zone. δ13C range from -6% to +10% (PDB); δ18O values range from +15% to +24% (VSMOW). Geochemical modeling software is used to model the alteration

Subcooled film boiling heat transfer on a high temperature sphere in very dilute Al2O3 nano-fluids

International Nuclear Information System (INIS)

Hyun Sun Park; Dereje Shiferaw; Bal Raj Sehgal

2005-01-01

Full text of publication follows: nano-fluids, or conventional liquids, e.g., water, with small concentration of nano-particles uniformly suspended, have attracted attention as a new heat transport medium with enhanced thermo-physical properties. Up to the present, only exploratory experiments on nano-fluids have been reported. Das et al (Int. J. Heat Mass Transfer 43, pp 3701-3707, 2003) conducted boiling experiments with water containing 38 nm Al 2 O 3 nano-particles. They observed deterioration in the nucleate boiling heat transfer due to the deposition of nano-particles. Boiling experiments conducted by Vassallo et al (Int. J. Heat Mass Transfer 47, pp 407-411, 2004) using silica nano-fluid using 0.4 mm diameter NiCr wire showed three times higher critical heat flux (CHF) and the wire traversed the film boiling region before it failed. Another independent experiment performed on 1 cm 2 square plate with a very low concentration of nano-particles ranging from 0.01 to 0.05 g/liter and at under pressure (2.89 psia), nano-fluids resulted in drastic 2∼3 times enhancement of the CHF (You and Kim, Appl. Phys. Lett. 83. No 16, 2003). However in all the aforementioned studies no appropriate explanation of the CHF enhancement has been advanced. The measured 2-3 times higher critical heat flux for very dilute nano-fluids may have high significance if such nano-fluids could be employed in heat transport systems. Recently, we investigated the effect of nano-particles on film boiling, which governs heat transfer during accident conditions in a reactor plant, e.g., in coolability of a degraded core, or a particulate debris bed or a core melt, and in steam explosions. Our previous experiments performed on film boiling in nano-fluids having larger concentrations of 5, 10, and 20 g/liter than those in You's experiments showed that the nano-fluids lower the film boiling temperature, decrease the film boiling heat transfer and provide a much thicker and more stable film than

Preparation and Characterization of Silver Liquid Thin Films for Magnetic Fluid Deformable Mirror

Directory of Open Access Journals (Sweden)

Lianchao Zhang

2015-01-01

Full Text Available Silver liquid thin film, formed by silver nanoparticles stacking and spreading on the surface of the liquid, is one of the important parts of magnetic fluid deformable mirror. First, silver nanoparticles were prepared by liquid phase chemical reduction method using sodium citrate as reducing agent and stabilizer and silver nitrate as precursor. Characterization of silver nanoparticles was studied using X-ray diffractometer, UV-vis spectrophotometer, and transmission electron microscope (TEM. The results showed that silver nanoparticles are spherical and have a good monodispersity. Additionally, the effect of the reaction conditions on the particle size of silver is obvious. And then silver liquid thin films were prepared by oil-water two-phase interface technology using as-synthesized silver nanoparticles. Properties of the film were investigated using different technology. The results showed that the film has good reflectivity and the particle size has a great influence on the reflectivity of the films. SEM photos showed that the liquid film is composed of multilayer silver nanoparticles. In addition, stability of the film was studied. The results showed that after being stored for 8 days under natural conditions, the gloss and reflectivity of the film start to decrease.

Evaluation tests of industrial vacuum bearings for space use

Science.gov (United States)

Obara, S.; Sasaki, A.; Haraguchi, M.; Imagawa, K.; Nishimura, M.; Kawashima, N.

2001-09-01

Tribological performance of industrial vacuum bearings was experimentally evaluated for space use. The bearings selected for investigation were an 8 mm bore-sized deep-groove ball bearing lubricated with a sputtered MoS2 film and that lubricated with an ion-plated Ag film, commercially delivered from three Japanese domestic bearing-manufacturers. Based on survey results of tribological requirements for the existing satellite mechanisms, four types of bearing tests were defined and conducted: a vacuum test at room temperature, an atmosphere-resistant test, a thermal vacuum test and a vibration test. In addition to these tests, variation in tribological performance of the industrial bearings was also investigated. The results of more than eighty tests demonstrated that the industrial vacuum bearings had sufficient lubrication lives with low frictional torque and their data were reasonably repeatable, indicating very good potentiality for space use.

Anisotropic permeable porous facing and slip velocity on squeeze film in an axially undefined journal bearing with ferrofluid lubricant

International Nuclear Information System (INIS)

Shah, R.C.; Bhat, M.V.

2004-01-01

Ferrofluid squeeze film in an axially undefined porous journal bearing was analyzed to determine its performance considering anisotropic permeability of the porous facing and slip velocity at the interface of porous matrix and film region using Jenkins flow model. Expressions were obtained for dimensionless pressure, load capacity and response time of the squeeze film. How to deduce results for no-slip case, isotropic porous case and for Neuringer-Rosensweig model case were indicated. The computed values of dimensionless load capacity and response time were displayed in graphical form. They increased with increasing values of eccentricity ratio and anisotropic parameter while they decreased with increasing values of slip parameter or material parameter of Jenkins model

The mobility of Nb in rutile-saturated NaCl- and NaF-bearing aqueous fluids from 1–6.5 GPa and 300–800 °C

Energy Technology Data Exchange (ETDEWEB)

Tanis, Elizabeth A.; Simon, Adam; Tschauner, Oliver; Chow, Paul; Xiao, Yuming; Burnley, Pamela; Cline II, Christopher J.; Hanchar, John M.; Pettke, Thomas; Shen, Guoyin; Zhao, Yusheng (MUN); (Michigan); (CIW); (UNLV); (Bern)

2015-08-26

Rutile (TiO₂) is an important host phase for high field strength elements (HFSE) such as Nb in metamorphic and subduction zone environments. The observed depletion of Nb in arc rocks is often explained by the hypothesis that rutile sequesters HFSE in the subducted slab and overlying sediment, and is chemically inert with respect to aqueous fluids evolved during prograde metamorphism in the forearc to subarc environment. However, field observations of exhumed terranes, and experimental studies, indicate that HFSE may be soluble in complex aqueous fluids at high pressure (i.e., >0.5 GPa) and moderate to high temperature (i.e., >300 °C). In this study, we investigated experimentally the mobility of Nb in NaCl- and NaF-bearing aqueous fluids in equilibrium with Nb-bearing rutile at pressure-temperature conditions applicable to fluid evolution in arc environments. Niobium concentrations in aqueous fluid at rutile saturation were measured directly by using a hydrothermal diamond-anvil cell (HDAC) and synchrotron X-ray fluorescence (SXRF) at 2.1 to 6.5 GPa and 300–500 °C, and indirectly by performing mass loss experiments in a piston-cylinder (PC) apparatus at ~1 GPa and 700–800 °C. The concentration of Nb in a 10 wt% NaCl aqueous fluid increases from 6 to 11 μg/g as temperature increases from 300 to 500 °C, over a pressure range from 2.1 to 2.8 GPa, consistent with a positive temperature dependence. The concentration of Nb in a 20 wt% NaCl aqueous fluid varies from 55 to 150 μg/g at 300 to 500 °C, over a pressure range from 1.8 to 6.4 GPa; however, there is no discernible temperature or pressure dependence. The Nb concentration in a 4 wt% NaF-bearing aqueous fluid increases from 180 to 910 μg/g as temperature increases from 300 to 500 °C over the pressure range 2.1 to 6.5 GPa. The data for the F-bearing fluid indicate that the Nb content of the fluid exhibits a dependence on temperature between 300 and 500 °C at ≥2 GPa, but there is no observed

Foil bearing performance in liquid nitrogen and liquid oxygen

Science.gov (United States)

Genge, Gary G.; Saville, Marshall; Gu, Alston

1993-01-01

Space transfer vehicles and other power and propulsion systems require long-life turbopumps. Rolling-element bearings used in current turbopumps do not have sufficient life for these applications. Process fluid foil bearings have established long life, with exceptional reliability, over a wide range of temperatures and fluids in many high-speed turbomachinery applications. However, actual data on bearing performance in cryogenic fluids has been minimal. The National Aeronautics and Space Administration (NASA) and AlliedSignal Aerospace Systems and Equipment (ASE) have attempted to characterize the leaf-type compliant foil bearing in oxygen and nitrogen. The work performed under a joint internal research and development program between Marshall Space Flight Center (MSFC) and ASE demonstrated that the foil bearing has load capacities of at least 266 psi in liquid oxygen and 352 psi in liquid nitrogen. In addition, the bearing demonstrated a direct damping coefficient of 40 to 50 lb-sec/in. with a damping ratio of .7 to 1.4 in. liquid nitrogen using a bearing sized for upper-stage turbopumps. With the results from this testing and the years of successful use in air cycle machines and other applications, leaf-type compliant foil bearings are ready for testing in liquid oxygen turbopumps.

SHABERTH - ANALYSIS OF A SHAFT BEARING SYSTEM (CRAY VERSION)

Science.gov (United States)

Coe, H. H.

1994-01-01

The SHABERTH computer program was developed to predict operating characteristics of bearings in a multibearing load support system. Lubricated and non-lubricated bearings can be modeled. SHABERTH calculates the loads, torques, temperatures, and fatigue life for ball and/or roller bearings on a single shaft. The program also allows for an analysis of the system reaction to the termination of lubricant supply to the bearings and other lubricated mechanical elements. SHABERTH has proven to be a valuable tool in the design and analysis of shaft bearing systems. The SHABERTH program is structured with four nested calculation schemes. The thermal scheme performs steady state and transient temperature calculations which predict system temperatures for a given operating state. The bearing dimensional equilibrium scheme uses the bearing temperatures, predicted by the temperature mapping subprograms, and the rolling element raceway load distribution, predicted by the bearing subprogram, to calculate bearing diametral clearance for a given operating state. The shaft-bearing system load equilibrium scheme calculates bearing inner ring positions relative to the respective outer rings such that the external loading applied to the shaft is brought into equilibrium by the rolling element loads which develop at each bearing inner ring for a given operating state. The bearing rolling element and cage load equilibrium scheme calculates the rolling element and cage equilibrium positions and rotational speeds based on the relative inner-outer ring positions, inertia effects, and friction conditions. The ball bearing subprograms in the current SHABERTH program have several model enhancements over similar programs. These enhancements include an elastohydrodynamic (EHD) film thickness model that accounts for thermal heating in the contact area and lubricant film starvation; a new model for traction combined with an asperity load sharing model; a model for the hydrodynamic rolling and

Experimental contribution to the study of gas bearings; Contribution experimentale a l'etude des paliers a gaz

Energy Technology Data Exchange (ETDEWEB)

Gobert, G

1962-07-01

Developments for gas-lubricated bearings are discussed. The study of how the fluid film behaves compared to what one can expect is discussed. Various devices are described which have allowed us to go up to peripheral velocity greater than 400 m/s, leading to rotational speed of several thousand revolutions per second. This is obtained by using an automatic setting for the distance between fixed and rotating walls. (author) [French] Le present travail debute par un apercu de l'etat actuel des connaissances sur le processus de la lubrification, notamment sur les paliers a lubrification par gaz. Apres une analyse effectuee au moyen des recentes theories de R. Comolet sur le film fluide entre disques paralleles, nous decrivons des machines dont les charges axiales et radiales specialement etudiees ont permis, au moyen d'un reglage automatique des jeux entre parois fixes et parois tournantes, d'atteindre des vitesses peripheriques superieures a 400 m/s correspondant a des vitesses de plusieurs milliers de tours par seconde. (auteur)

Force effects on rotor of squeeze film damper using Newtonian and non-Newtonian fluid

Science.gov (United States)

Dominik, Šedivý; Petr, Ferfecki; Simona, Fialová

2017-09-01

This article presents the evaluation of force effects on rotor of squeeze film damper. Rotor is eccentric placed and its motion is translate-circular. The amplitude of rotor motion is smaller than its initial eccentricity. The force effects are calculated from pressure and viscous forces which were gained by using computational modeling. Two types of fluid were considered as filling of damper. First type of fluid is Newtonian (has constant viscosity) and second type is magnetorheological fluid (does not have constant viscosity). Viscosity of non-Newtonian fluid is given using Bingham rheology model. Yield stress is a function of magnetic induction which is described by many variables. The most important variables of magnetic induction are electric current and gap width which is between rotor and stator. Comparison of application two given types of fluids is shown in results.

Effects on the structure of monolayer and submonolayer fluid nitrogen films by the corrugation in the holding potential of nitrogen molecules

DEFF Research Database (Denmark)

Hansen, Flemming Yssing

2001-01-01

of interactions were indicated by the comparison of the calculated and measured isosteric heats of adsorption in fluid films of nitrogen molecules on graphite. The melting temperatures were lowered by 7K and a region of liquid-gas coexistence was observed for films on the smooth graphite surface indicating......The effects of corrugation in the holding potential of nitrogen molecules on the structure of fluid monolayer and submonolayer films of the molecules on a solid substrate was studied using molecular dynamics simulation. Including McLachlan mediation of the intermolecular potential in a model...

The Thermohydrodynamic Analysis of Sliding Bearing High-Speed Motorized Spindle by Rotor Dynamic

Directory of Open Access Journals (Sweden)

Li Songsheng

2017-01-01

Full Text Available This is paper presents thermohydrodynamic characteristics of high speed motorized spindle sliding bearing rotor system. The dynamic characteristic of the oil film bearing is affected by temperature increment, thereby affecting the high-speed spindle rotor system dynamics. This study applied the hydrodynamic lubrication theory, the influence of temperature on the viscosity of lubricating oil, associated with the bearing stiffness, oil film damping and other performance parameters, is considered in generalized Reynolds equation of oil film bearing. The theoretical model of the sliding bearing rotor system is established by using the transfer matrix method to analyze the dynamic characteristic and verified by experiments. The results show the high temperature environment in the motorized spindle and the friction of the bearing lead to oil temperature rise and viscosity reduction, which influences the bearing capacity, stiffness and damping, hence impact on the critical speeds and modal shapes of the sliding bearing rotor system.

Scaling crossover in thin-film drag dynamics of fluid drops in the Hele-Shaw cell

Science.gov (United States)

Okumura, Ko; Yahashi, Misato; Kimoto, Natsuki

2016-11-01

We study both experimentally and theoretically the descending motion due to gravity of a fluid drop surrounded by another immiscible fluid in a confined space between two parallel plates, i.e., in the Hele-Shaw cell. As a result, we show a new scaling regime of a nonlinear drag friction in viscous liquid that replaces the well-known Stokes' drag friction through a clear collapse of experimental data thanks to the scaling law. In the novel regime, the dissipation in the liquid thin film formed between the drop and cell walls governs the dynamics. The crossover of this scaling regime to another scaling regime in which the dissipation inside the droplet is dominant is clearly demonstrated and a phase diagram separating these scaling regimes is presented. To be published as, Y. Yahashi, N. Kimoto and K. Okumura, Scaling crossover in thin-film drag dynamics of fluid drops in the Hele-Shaw cell, Sci. Rep.(CC BY 4.0). This research was partly supported by ImPACT Program of Council for Science, Technology and Innovation (Cabinet Office, Government of Japan).

Beyond the standard two-film theory: Computational fluid dynamics simulations for carbon dioxide capture in a wetted wall column

Energy Technology Data Exchange (ETDEWEB)

Wang, Chao; Xu, Zhijie; Lai, Canhai; Sun, Xin

2018-07-01

The standard two-film theory (STFT) is a diffusion-based mechanism that can be used to describe gas mass transfer across liquid film. Fundamental assumptions of the STFT impose serious limitations on its ability to predict mass transfer coefficients. To better understand gas absorption across liquid film in practical situations, a multiphase computational fluid dynamics (CFD) model fully equipped with mass transport and chemistry capabilities has been developed for solvent-based carbon dioxide (CO2) capture to predict the CO2 mass transfer coefficient in a wetted wall column. The hydrodynamics is modeled using a volume of fluid method, and the diffusive and reactive mass transfer between the two phases is modeled by adopting a one-fluid formulation. We demonstrate that the proposed CFD model can naturally account for the influence of many important factors on the overall mass transfer that cannot be quantitatively explained by the STFT, such as the local variation in fluid velocities and properties, flow instabilities, and complex geometries. The CFD model also can predict the local mass transfer coefficient variation along the column height, which the STFT typically does not consider.

Full Life Wind Turbine Gearbox Lubricating Fluids

Energy Technology Data Exchange (ETDEWEB)

Lutz, Glenn A.; Jungk, Manfred; Bryant, Jonathan J.; Lauer, Rebecca S.; Chobot, Anthony; Mayer, Tyler; Palmer, Shane; Kauffman, Robert E.

2012-02-28

Industrial gear box lubricants typically are hydrocarbon based mineral oils with considerable amounts of additives to overcome the lack of base fluid properties like wear protection, oxidation stability, load carrying capacity, low temperature solidification and drop of viscosity at higher temperatures. For today's wind turbine gearboxes, the requirements are more severe and synthetic hydrocarbon oils are used to improve on this, but all such hydrocarbon based lubricants require significant amounts of Extreme Pressure (EP) additives to meet performance requirements. Perfluoropolyether (PFPE) fluids provide load carrying capacity as an inherent property. During the course of the project with the main tasks of 'Establish a Benchmark', 'Lubricant Evaluation', 'Full Scale Gearbox Trial' and 'Economic Evaluation', the PAO Reference oil exhibited significant changes after laboratory gear testing, in service operation in the field and full scale gearbox trial. Four hydrocarbon base oils were selected for comparison in the benchmarking exercise and showed variation with respect to meeting the requirements for the laboratory micro-pitting tests, while the PFPE fluid exceeded the requirements even with the material taken after the full scale gear box trial. This is remarkable for a lubricant without EP additives. Laboratory bearing tests performed on the PFPE fluids before and after the full scale gear box trial showed the results met requirements for the industry standard. The PFPE fluid successfully completed the full scale gear box test program which included baseline and progressive staged load testing. The evaluation of gears showed no micro-pitting or objectionable wear. By the final stage, lubricant film thickness had been reduced to just 21% of its original value, this was by design and resulted in a lambda ratio of well below 1. This test design scenario of a low lambda ratio is a very undesirable lubrication condition

Computational design of rolling bearings

CERN Document Server

Nguyen-Schäfer, Hung

2016-01-01

This book comprehensively presents the computational design of rolling bearings dealing with many interdisciplinary difficult working fields. They encompass elastohydrodynamics (EHD), Hertzian contact theory, oil-film thickness in elastohydrodynamic lubrication (EHL), bearing dynamics, tribology of surface textures, fatigue failure mechanisms, fatigue lifetimes of rolling bearings and lubricating greases, Weibull distribution, rotor balancing, and airborne noises (NVH) in the rolling bearings. Furthermore, the readers are provided with hands-on essential formulas based on the up-to-date DIN ISO norms and helpful examples for computational design of rolling bearings. The topics are intended for undergraduate and graduate students in mechanical and material engineering, research scientists, and practicing engineers who want to understand the interactions between these working fields and to know how to design the rolling bearings for automotive industry and many other industries.

On Controllable Elastohydrodynamic Fluid Film Bearings

DEFF Research Database (Denmark)

Haugaard, Martin Asger

analyses as well as nonlinear time domain analyses of ATPJBs. Examples of all of these analysis types are presented. As opposed to some of the more convoluted modelling methods in the literature, the presented one permits dimensional analysis in a straight forward and intuitive manner. Dimensional analyses...

Analytical prediction of CHF by FIDAS code based on three-fluid and film-dryout model

International Nuclear Information System (INIS)

Sugawara, Satoru

1990-01-01

Analytical prediction model of critical heat flux (CHF) has been developed on the basis of film dryout criterion due to droplets deposition and entrainment in annular mist flow. Critical heat flux in round tubes were analyzed by the Film Dryout Analysis Code in Subchannels (FIDAS) which is based on the three-fluid, three-field and newly developed film dryout model. Predictions by FIDAS were compared with the world-wide experimental data on CHF obtained in water and Freon for uniformly and non-uniformly heated tubes under vertical upward flow condition. Furthermore, CHF prediction capability of FIDAS was compared with those of other film dryout models for annular flow and Katto's CHF correlation. The predictions of FIDAS are in sufficient agreement with the experimental CHF data, and indicate better agreement than the other film dryout models and empirical correlation of Katto. (author)

Transient response of two lobe aerodynamic journal bearing

Directory of Open Access Journals (Sweden)

Saurabh Kumar Yadav

2018-03-01

Full Text Available The dynamic behavior of a rotor-dynamic system is greatly affected by the performance of aerodynamic bearing and the performance of bearing is characterized by the stiffness and damping coefficients. In the present work, stiffness and damping coefficients of bearing are computed and the performance of the bearing is greatly changed with the change in bearing air film profile. The effect of lobe offset factors on the transient performance of aerodynamic bearing is presented. Bifurcation and Poincare diagrams of two lobe journal bearing have been presented for different offset factors. A bearing designer can judge the bearing performance based on bifurcation diagrams.

Implementation of wall film condensation model to two-fluid model in component thermal hydraulic analysis code CUPID - 15237

International Nuclear Information System (INIS)

Lee, J.H.; Park, G.C.; Cho, H.K.

2015-01-01

In the containment of a nuclear reactor, the wall condensation occurs when containment cooling system and structures remove the mass and energy release and this phenomenon is of great importance to ensure containment integrity. If the phenomenon occurs in the presence of non-condensable gases, their accumulation near the condensate film leads to significant reduction in heat transfer during the condensation. This study aims at simulating the wall film condensation in the presence of non-condensable gas using CUPID, a computational multi-fluid dynamics code, which is developed by the Korea Atomic Energy Research Institute (KAERI) for the analysis of transient two-phase flows in nuclear reactor components. In order to simulate the wall film condensation in containment, the code requires a proper wall condensation model and liquid film model applicable to the analysis of the large scale system. In the present study, the liquid film model and wall film condensation model were implemented in the two-fluid model of CUPID. For the condensation simulation, a wall function approach with heat and mass transfer analogy was applied in order to save computational time without considerable refinement for the boundary layer. This paper presents the implemented wall film condensation model and then, introduces the simulation result using CUPID with the model for a conceptual condensation problem in a large system. (authors)

Omental torsion in a captive polar bear (Ursus maritimus).

Science.gov (United States)

Mendez-Angulo, Jose L; Funes, Francisco J; Trent, Ava M; Willette, Michelle; Woodhouse, Kerry; Renier, Anna C

2014-03-01

This is the first case report of an omental torsion in a polar bear (Ursus maritimus). A captive, 23-yr-old, 250-kg, intact female polar bear presented to the University of Minnesota Veterinary Medical Center with a 2-day history of lethargy, depression, and vomiting. Abdominal ultrasound identified large amounts of hyperechoic free peritoneal fluid. Ultrasound-guided abdominocentesis was performed and yielded thick serosanguinous fluid compatible with a hemoabdomen. An exploratory laparotomy revealed a large amount of malodorous, serosanguineous fluid and multiple necrotic blood clots associated with a torsion of the greater omentum and rupture of a branch of the omental artery. A partial omentectomy was performed to remove the necrotic tissue and the abdomen was copiously lavaged. The polar bear recovered successfully and is reported to be clinically well 6 mo later. This condition should be considered as a differential in bears with clinical signs of intestinal obstruction and hemoabdomen.

Development, implementation and assessment of specific, two-fluid closure laws for inverted-annular film-boiling

Energy Technology Data Exchange (ETDEWEB)

Cachard, F. de [Laboratory for Thermal Hydraulics, Villigen (Switzerland)

1995-09-01

Inverted-Annular Film-Boiling (IAFB) is one of the post-burnout heat transfer modes taking place during the reflooding phase of the loss-of-coolant accident, when the liquid at the quench front is subcooled. Under IAFB conditions, a continuous, liquid core is separated from the wall by a superheated vapour film. the heat transfer rate in IAFB is influenced by the flooding rate, liquid subcooling, pressure, and the wall geometry and temperature. These influences can be accounted by a two-fluid model with physically sound closure laws for mass, momentum and heat transfers between the wall, the vapour film, the vapour-liquid interface, and the liquid core. Such closure laws have been developed and adjusted using IAFB-relevant experimental results, including heat flux, wall temperature and void fraction data. The model is extensively assessed against data from three independent sources. A total of 46 experiments have been analyzed. The overall predictions are good. The IAFB-specific closure laws proposed have also intrinsic value, and may be used in other two-fluid models. They should allow to improve the description of post-dryout, low quality heat transfer by the safety codes.

On the simplifications for the thermal modeling of tilting-pad journal bearings under thermoelastohydrodynamic regime

DEFF Research Database (Denmark)

Cerda Varela, Alejandro Javier; Fillon, Michel; Santos, Ilmar

2012-01-01

formulation for inclusion of the heat transfer effects between oil film and pad surface. Such simplified approach becomes necessary when modeling the behavior of tilting-pad journal bearings operating on controllable lubrication regime. Three different simplified heat transfer models are tested, by comparing...... are strongly dependent on the Reynolds number for the oil flow in the bearing. For bearings operating in laminar regime, the decoupling of the oil film energy equation solving procedure, with no heat transfer terms included, with the pad heat conduction problem, where the oil film temperature is applied......The relevance of calculating accurately the oil film temperature build up when modeling tilting-pad journal bearings is well established within the literature on the subject. This work studies the feasibility of using a thermal model for the tilting-pad journal bearing which includes a simplified...

Influence of film dimensions on film droplet formation.

Science.gov (United States)

Holmgren, Helene; Ljungström, Evert

2012-02-01

Aerosol particles may be generated from rupturing liquid films through a droplet formation mechanism. The present work was undertaken with the aim to throw some light on the influence of film dimensions on droplet formation with possible consequences for exhaled breath aerosol formation. The film droplet formation process was mimicked by using a purpose-built device, where fluid films were spanned across holes of known diameters. As the films burst, droplets were formed and the number and size distributions of the resulting droplets were determined. No general relation could be found between hole diameter and the number of droplets generated per unit surface area of fluid film. Averaged over all film sizes, a higher surface tension yielded higher concentrations of droplets. Surface tension did not influence the resulting droplet diameter, but it was found that smaller films generated smaller droplets. This study shows that small fluid films generate droplets as efficiently as large films, and that droplets may well be generated from films with diameters below 1 mm. This has implications for the formation of film droplets from reopening of closed airways because human terminal bronchioles are of similar dimensions. Thus, the results provide support for the earlier proposed mechanism where reopening of closed airways is one origin of exhaled particles.

Small-scale modelling of cementation by descending silica-bearing fluids: Explanation of the origin of arenitic caves in South American tepuis

Science.gov (United States)

Aubrecht, R.; Lánczos, T.; Schlögl, J.; Audy, M.

2017-12-01

Geoscientific research was performed on South American table mountains (tepuis) and in their sandstone cave systems. To explain speleogenesis in these poorly soluble rocks, two theories were introduced: a) arenization theory implying selective weathering of quartz along grain boundaries and releasing of sand grains, b) selective lithification theory implying cementation by descending silica-bearing fluid flow. The latter theory presumes that the descending fluid flow becomes unstable on the interface between two layers with different porosity and splits to separate flow channels (so-called ;finger flow;). The arenites outside these channels remain uncemented. To verify the latter theory, small-scale modelling was performed, using layered sands and sodium-silicate solution. Fine to medium sand was used (0.08-0.5 mm), along with a coarse sand fraction (0.5-1.5 mm). The sands were layered and compacted in a transparent plastic boxes. Three liters of sodium-silicate solution (so-called water glass) were left to drip for several hours to the top of the sediment. The fine-grained layers were perfectly laterally impregnated, whereas the descending fluid flows split to ;fingers; in the coarse-grained layers due their higher hydraulic conductivity. This small-scale laboratory simulation mimics the real diagenesis by descending silica-bearing fluids and matches the real phenomena observed on the tepuis. The resulting cemented constructions closely mimic many geomorphological features observed on tepuis and inside their caves, e.g. ;finger-flow; pillars, overhangs, imperfectly formed (aborted) pillars in forms of hummocks hanging from ceilings, locally also thicker central pillars that originated by merging of smaller fluid-flow channels. The modelling showed that selective lithification theory can explain most of the geomorphological aspects related to the speleogenesis in tepuis.

Travelling-wave similarity solutions for a steadily translating slender dry patch in a thin fluid film

KAUST Repository

Yatim, Y. M.; Duffy, B. R.; Wilson, S. K.

2013-01-01

A novel family of three-dimensional travelling-wave similarity solutions describing a steadily translating slender dry patch in an infinitely wide thin fluid film on an inclined planar substrate when surface-tension effects are negligible

Multiscale Computational Fluid Dynamics: Methodology and Application to PECVD of Thin Film Solar Cells

Directory of Open Access Journals (Sweden)

Marquis Crose

2017-02-01

Full Text Available This work focuses on the development of a multiscale computational fluid dynamics (CFD simulation framework with application to plasma-enhanced chemical vapor deposition of thin film solar cells. A macroscopic, CFD model is proposed which is capable of accurately reproducing plasma chemistry and transport phenomena within a 2D axisymmetric reactor geometry. Additionally, the complex interactions that take place on the surface of a-Si:H thin films are coupled with the CFD simulation using a novel kinetic Monte Carlo scheme which describes the thin film growth, leading to a multiscale CFD model. Due to the significant computational challenges imposed by this multiscale CFD model, a parallel computation strategy is presented which allows for reduced processing time via the discretization of both the gas-phase mesh and microscopic thin film growth processes. Finally, the multiscale CFD model has been applied to the PECVD process at industrially relevant operating conditions revealing non-uniformities greater than 20% in the growth rate of amorphous silicon films across the radius of the wafer.

Global dynamics of shaft lines of turbo-machineries coupled to surrounding fluids: application to the case of fluid sheets; Dynamique globale des lignes d'arbres de turbomachines couplees aux fluides environnants: application au cas des lames fluides

Energy Technology Data Exchange (ETDEWEB)

Lornage, D.

2001-12-15

Shaft lines of turbo-machineries have to stand increasing reliability, efficiency and safety requirements. A precise modeling of the rotating parts with all possible coupling has become necessary. In this context, this work aims to develop a global modeling of rotating wheel/shaft system inside a surrounding fluid in order to foresee its dynamical behaviour. The use and advantage of Eulerian, Lagrangian and mixed (arbitrary Lagrangian Eulerian - ALE) formulations is recalled first. A bibliographic synthesis of the classical techniques used in structure mechanics and of coupling techniques for rotating machines is presented. The coupling technique retained is presented. It uses fluid and structure models independently developed and validated. The structure domain is discretized by the finite-element method. The fluid domain is discretized by the finite-difference method taking into consideration the hypotheses linked with thin films. A modal base projection combined with a mesh at the fluid-structure interface allows an efficient, adaptable and evolutive coupling. Finally, the method is applied to 3 test-cases. The first two ones comprise a shaft/disc system coupled to a fluid sheet between the disc and the casing and to an hydrodynamic bearing. Both cases allow a first validation of the coupling method. The third case aims to study a structure closer to a real system made of a shaft and a wheel coupled to a fluid sheet between a flange and a casing. These three applications allow to show the trends linked with the fluid effects and the coupling between the flexible sub-parts of the structure. (J.S.)

Influence of Stern Shaft Inclination on the Cooling Performance of Water-Lubricated Bearing

Directory of Open Access Journals (Sweden)

Zou Li

2016-01-01

Full Text Available The water film model of the marine water-lubricated stern bearing was established by FLUENT. The influence law of water flow rate on the cooling performance of water-lubricated bearing was studied in consideration of the stern shaft inclination. It will be helpful to improve the performance of marine water-lubricated stern bearing and both security and reliability of propulsion system. The simulation results show that the increase of cooling water flow rate in a certain range can effectively reduce bearing temperature. The bearing temperature rises sharply with thinning of water film thickness which is caused by the increase of inclination angle. Larger inclination angle can deteriorate the operating reliability of bearing.

Metal ion concentrations in body fluids after implantation of hip replacements with metal-on-metal bearing--systematic review of clinical and epidemiological studies.

Directory of Open Access Journals (Sweden)

Albrecht Hartmann

Full Text Available INTRODUCTION: The use of metal-on-metal (MoM total hip arthroplasty (THA increased in the last decades. A release of metal products (i.e. particles, ions, metallo-organic compounds in these implants may cause local and/or systemic adverse reactions. Metal ion concentrations in body fluids are surrogate measures of metal exposure. OBJECTIVE: To systematically summarize and critically appraise published studies concerning metal ion concentrations after MoM THA. METHODS: Systematic review of clinical trials (RCTs and epidemiological studies with assessment of metal ion levels (cobalt, chromium, titanium, nickel, molybdenum in body fluids after implantation of metalliferous hip replacements. Systematic search in PubMed and Embase in January 2012 supplemented by hand search. Standardized abstraction of pre- and postoperative metal ion concentrations stratified by type of bearing (primary explanatory factor, patient characteristics as well as study quality characteristics (secondary explanatory factors. RESULTS: Overall, 104 studies (11 RCTs, 93 epidemiological studies totaling 9.957 patients with measurement of metal ions in body fluids were identified and analyzed. Consistently, median metal ion concentrations were persistently elevated after implantation of MoM-bearings in all investigated mediums (whole blood, serum, plasma, erythrocytes, urine irrespective of patient characteristics and study characteristics. In several studies very high serum cobalt concentrations above 50 µg/L were measured (detection limit typically 0.3 µg/L. Highest metal ion concentrations were observed after treatment with stemmed large-head MoM-implants and hip resurfacing arthroplasty. DISCUSSION: Due to the risk of local and systemic accumulation of metallic products after treatment with MoM-bearing, risk and benefits should be carefully balanced preoperatively. The authors support a proposed "time out" for stemmed large-head MoM-THA and recommend a restricted

Tribo-characteristics of self-lubricating ball bearings for the LE-7 liquid hydrogen rocket-turbopump

Science.gov (United States)

Nosaka, Masataka; Oike, Mamoru; Kikuchi, Masataka; Kamijo, Kenjiro; Tajiri, Masanori

1993-07-01

The tribo characteristics of self-lubricating 40-mm-bore ball bearings with a retainer of glass cloth-polytetrafluoroethylene (PTFE) laminate, which has elliptical pockets with a large pocket clearance, were tested under thrust loads at speeds up to 50,000 rpm, 2 million DN, in liquid hydrogen (LH2) and in liquid nitrogen (LN2). During testing, the bearing torque, outer-race temperature, and electric resistance between the inner and outer races were monitored to verify the formation and rupture of a PTFE transfer film. Testing showed that the bearings having the elliptical retainer pockets were superior to the conventional bearings with circular pockets. It was determined that, at the maximum inner race spinning velocity of about 5 m/s, a PTFE transfer film could sustain the maximum Hertz stress, up to about 2000 N/sq mm, in LH2, without severe film rupture resulting in bearing seizure. In LN2, the critical load capacity of PTFE transfer film with bearing seizure was about 2700 N/sq mm.

Experimental contribution to the study of gas bearings; Contribution experimentale a l'etude des paliers a gaz

Energy Technology Data Exchange (ETDEWEB)

Gobert, G

1962-07-01

Developments for gas-lubricated bearings are discussed. The study of how the fluid film behaves compared to what one can expect is discussed. Various devices are described which have allowed us to go up to peripheral velocity greater than 400 m/s, leading to rotational speed of several thousand revolutions per second. This is obtained by using an automatic setting for the distance between fixed and rotating walls. (author) [French] Le present travail debute par un apercu de l'etat actuel des connaissances sur le processus de la lubrification, notamment sur les paliers a lubrification par gaz. Apres une analyse effectuee au moyen des recentes theories de R. Comolet sur le film fluide entre disques paralleles, nous decrivons des machines dont les charges axiales et radiales specialement etudiees ont permis, au moyen d'un reglage automatique des jeux entre parois fixes et parois tournantes, d'atteindre des vitesses peripheriques superieures a 400 m/s correspondant a des vitesses de plusieurs milliers de tours par seconde. (auteur)

MEDULLOBLASTOMA IN A GRIZZLY BEAR (URSUS ARCTOS HORRIBLIS).

Science.gov (United States)

Mitchell, Jeffrey W; Thomovsky, Stephanie A; Chen, Annie V; Layton, Arthur W; Haldorson, Gary; Tucker, Russell L; Roberts, Gregory

2015-09-01

A 3-yr-old female spayed grizzly bear (Ursus arctos horribilis) was evaluated for seizure activity along with lethargy, inappetence, dull mentation, and aggressive behavior. Magnetic resonance (MR) examination of the brain revealed a contrast-enhanced right cerebellar mass with multifocal smaller nodules located in the left cerebellum, thalamus, hippocampus, and cerebrum with resultant obstructive hydrocephalus. Cerebrospinal fluid analysis revealed mild mononuclear pleocytosis, with differentials including inflammatory versus neoplastic processes. Blood and cerebrospinal fluid were also submitted for polymerase chain reaction and agar gel immunodiffusion to rule out infectious causes of meningitis/encephalitis. While awaiting these results, the bear was placed on steroid and antibiotic therapy. Over the next week, the bear deteriorated; she died 1 wk after MR. A complete postmortem examination, including immunohistochemisty, revealed the cerebellar mass to be a medulloblastoma. This is the only case report, to the authors' knowledge, describing a medulloblastoma in a grizzly bear.

Nonlinear Dynamic Response of Compliant Journal Bearings

Directory of Open Access Journals (Sweden)

Glavatskih S.

2012-07-01

Full Text Available This paper investigates the dynamic response of the compliant tilting pad journal bearings subjected to synchronous excitation. Bearing compliance is affected by the properties of pad liner and pad support geometry. Different unbalance eccentricities are considered. It is shown that bearing dynamic response is non-linear. Journal orbit complexity increases with pad compliance though the orbit amplitudes are marginally affected at low loads. At high loads, the journal is forced to operate outside the bearing clearance. The polymer liner reduces the maximum oil film pressure by a factor of 2 when compared to the white metal liner. The nonlinear dynamic response of compliant tilting pad journal bearings is thoroughly discussed.

Metal Ion Concentrations in Body Fluids after Implantation of Hip Replacements with Metal-on-Metal Bearing – Systematic Review of Clinical and Epidemiological Studies

Science.gov (United States)

Hartmann, Albrecht; Hannemann, Franziska; Lützner, Jörg; Seidler, Andreas; Drexler, Hans; Günther, Klaus-Peter; Schmitt, Jochen

2013-01-01

Introduction The use of metal-on-metal (MoM) total hip arthroplasty (THA) increased in the last decades. A release of metal products (i.e. particles, ions, metallo-organic compounds) in these implants may cause local and/or systemic adverse reactions. Metal ion concentrations in body fluids are surrogate measures of metal exposure. Objective To systematically summarize and critically appraise published studies concerning metal ion concentrations after MoM THA. Methods Systematic review of clinical trials (RCTs) and epidemiological studies with assessment of metal ion levels (cobalt, chromium, titanium, nickel, molybdenum) in body fluids after implantation of metalliferous hip replacements. Systematic search in PubMed and Embase in January 2012 supplemented by hand search. Standardized abstraction of pre- and postoperative metal ion concentrations stratified by type of bearing (primary explanatory factor), patient characteristics as well as study quality characteristics (secondary explanatory factors). Results Overall, 104 studies (11 RCTs, 93 epidemiological studies) totaling 9.957 patients with measurement of metal ions in body fluids were identified and analyzed. Consistently, median metal ion concentrations were persistently elevated after implantation of MoM-bearings in all investigated mediums (whole blood, serum, plasma, erythrocytes, urine) irrespective of patient characteristics and study characteristics. In several studies very high serum cobalt concentrations above 50 µg/L were measured (detection limit typically 0.3 µg/L). Highest metal ion concentrations were observed after treatment with stemmed large-head MoM-implants and hip resurfacing arthroplasty. Discussion Due to the risk of local and systemic accumulation of metallic products after treatment with MoM-bearing, risk and benefits should be carefully balanced preoperatively. The authors support a proposed „time out“ for stemmed large-head MoM-THA and recommend a restricted indication for hip

Nonlinear effects caused by coupling misalignment in rotors equipped with journal bearings

Science.gov (United States)

Pennacchi, Paolo; Vania, Andrea; Chatterton, Steven

2012-07-01

Misalignment is one of the most common sources of trouble of rotating machinery when rigid couplings connect the shafts. Ideal alignment of the shafts is difficult to be obtained and rotors may present angular and/or parallel misalignment (defined also as radial misalignment or offset). During a complete shaft revolution, a periodical change of the bearings load occurs in hyperstatic shaft-lines, if coupling misalignment between the shafts is excessive. If the rotating machine is equipped with fluid-film journal bearings, the change of the loads on the bearing causes also the variation of their instantaneous dynamic characteristics, i.e. damping and stiffness, and the complete system cannot be considered any longer as linear. Despite misalignment is often observed in the practice, there are relatively few studies about this phenomenon in literature and their results are sometimes conflicting. The authors aim at modeling accurately this phenomenon, for the first time in this paper, and giving pertinent diagnostic information. The proposed method is suitable for every type of shaft-line supported by journal bearings. A finite element model is used for the hyperstatic shaft-line, while bearing characteristics are calculated by integrating Reynolds equation as a function of the instantaneous load acting on the bearings, caused also by the coupling misalignment. The results obtained by applying the proposed method are shown by means of the simulation, in the time domain, of the dynamical response of a hyperstatic shaft-line. Nonlinear effects are highlighted and the spectral components of the system response are analyzed, in order to give diagnostic information about the signature of this type of fault.

Experimental test of static and dynamic characteristics of tilting-pad thrust bearings

Directory of Open Access Journals (Sweden)

Annan Guo

2015-07-01

Full Text Available The axial vibration in turbine machine has attracted more and more interest. Tilting-pad thrust bearings are widely used in turbine machines to support the axial load. The dynamic properties generated by oil film of the thrust pad have important effects on the axial vibration of the rotor-bearing system. It is necessary to develop the method to test the dynamic characteristics of thrust bearings. A new rig has been developed. The facility allows a complete set of bearing operating parameters to be measured. Parameters measured include oil temperatures, oil-film thickness, and pressure. The static load and dynamic load can be added on the thrust bearing in the vertical direction at the same time. The relative and absolute displacement vibrations of the test experimental bearing with the changes of dynamic force are measured, and the dynamic characteristics of the test bearing are obtained. The experimental results show clearly that the operating conditions influence largely on the pad static and dynamic characteristics.

60NiTi Intermetallic Material Evaluation for Lightweight and Corrosion Resistant Spherical Sliding Bearings for Aerospace Applications

Science.gov (United States)

DellaCorte, Christopher; Jefferson, Michael

2015-01-01

NASA Glenn Research Center and the Kamatics subsidiary of the Kaman Corporation conducted the experimental evaluation of spherical sliding bearings made with 60NiTi inner races. The goal of the project was to assess the feasibility of manufacturing lightweight, corrosion resistant bearings utilizing 60NiTi for aerospace and industrial applications. NASA produced the bearings in collaboration with Abbott Ball Corporation and Kamatics fabricated bearing assemblies utilizing their standard reinforced polymer liner material. The assembled bearings were tested in oscillatory motion at a load of 4.54kN (10,000 lb), according to the requirements of the plain bearing specification SAE AS81820. Several test bearings were exposed to hydraulic fluid or aircraft deicing fluid prior to and during testing. The results show that the 60NiTi bearings exhibit tribological performance comparable to conventional stainless steel (440C) bearings. Further, exposure of 60NiTi bearings to the contaminant fluids had no apparent performance effect. It is concluded that 60NiTi is a feasible bearing material for aerospace and industrial spherical bearing applications.

Design of instantaneous liquid film thickness measurement system for conductive or non-conductive fluid with high viscosity

Directory of Open Access Journals (Sweden)

Yongxin Yu

2017-06-01

Full Text Available In the paper, a new capacitive sensor with a dielectric film coating was designed to measure the thickness of the liquid film on a flat surface. The measured medium can be conductive or non-conductive fluid with high viscosity such as silicone oil, syrup, CMC solution and melt. With the dielectric film coating, the defects caused by the humidity in a capacitor can be avoided completely. With a excitation frequency 0-20kHz, the static permittivity of capacitive sensor is obtained and stable when small thicknesses are monitored within the frequency of 0-3kHz. Based on the measurement principle, an experimental system was designed and verified including calibration and actual measurement for different liquid film thickness. Experimental results showed that the sensitivity, the resolution, repeatability and linear range of the capacitive sensor are satisfied to the liquid film thickness measurement. Finally, the capacitive measuring system was successfully applied to the water, silicone oil and syrup film thickness measurement.

Travelling-wave similarity solutions for a steadily translating slender dry patch in a thin fluid film

KAUST Repository

Yatim, Y. M.

2013-01-01

A novel family of three-dimensional travelling-wave similarity solutions describing a steadily translating slender dry patch in an infinitely wide thin fluid film on an inclined planar substrate when surface-tension effects are negligible is obtained, the flow being driven by gravity and/or a prescribed constant shear stress on the free surface of the film. For both driving mechanisms, the dry patch has a parabolic shape (which may be concave up or concave down the substrate), and the film thickness increases monotonically away from the contact lines to its uniform far-field value. The two most practically important cases of purely gravity-driven flow and of purely surface-shear-stress-driven flow are analysed separately. © 2013 AIP Publishing LLC.

Squeeze-film Lubrication of the Human Ankle Joint with Synovial Fluid Filtrated by Articular Cartilage with the Superficial Zone Worn out

Czech Academy of Sciences Publication Activity Database

Hlaváček, Miroslav

2000-01-01

Roč. 33, č. 11 (2000), s. 1415-1422 ISSN 0021-9290 R&D Projects: GA ČR GA103/00/0008 Keywords : human ankle joint * squeeze-film lubrication * synovial fluid filtration * worn-out cartilage superficial zone Subject RIV: BK - Fluid Dynamics Impact factor: 1.474, year: 2000

Nuclear reactor core support incorporating also a cooling fluid flow system

International Nuclear Information System (INIS)

Pennell, W.E.

1975-01-01

A description is given of a core bearing plate with several modular intake units having cooling fluid intake openings on their lower extensions, and on their upper ends located above the bearing plate, at least one fuel assembly which is thus in communication with the area under the bearing plate through the modular intake unit. The means for introducing the cooling fluid into the reactor vessel area are located under the bearing plate. The lower ends of the modular intake have ribs arranged essentially on a plane and join together with openings provided between the seals, in such a manner that the ribs form a barrier. The cooling fluid intake openings are located above this barrier, so that the cooling fluid is compelled to cross it before penetrating into the modular intake units [fr

Ore bearing system and hydrological characteristics of mineralized sector in Hushiliang area

International Nuclear Information System (INIS)

Zhang Zhaolin; Liu Zhengbang; Miao Aisheng

2010-01-01

Hushiliang area is one of the best uranium ore bearing areas in Erdos basin from the point of fluvial sedimentary system and uranium geochemical environment, So far, three mineralized sector has been found that are Nalingou, Nongshengxin, Baobeigou. By using the first-hand data of uranium regional survey in this area lately and systematically comparing and analyzing of the hydrological structure in the mineralized sector of this area, the thesis ascertain the ore and water bearing fluid reservoir's spatial relationship generally, and argues that the Zhiluo formation ore and water bearing fluid reservoir in this area is a unified underwater ore bearing system, and the orebody's hydrological structure is propitious in the distributary channel and unpropitious in the main channel because of deep ore bearing layer to the ISL. (authors)

An improved FT-TIMS method of measuring uranium isotope ratios in the uranium-bearing particles

International Nuclear Information System (INIS)

Chen, Yan; Wang, Fan; Zhao, Yong-Gang; Li, Li-Li; Zhang, Yan; Shen, Yan; Chang, Zhi-Yuan; Guo, Shi-Lun; Wang, Xiao-Ming; Cui, Jian-Yong; Liu, Yu-Ang

2015-01-01

An improved method of Fission Track technique combined with Thermal Ionization Mass Spectrometry (FT-TIMS) was established in order to determine isotope ratio of uranium-bearing particle. Working standard of uranium oxide particles with a defined diameter and isotopic composition were prepared and used to review the method. Results showed an excellent agreement with certified values. The developed method was used to analyze isotope ratio of single uranium-bearing particle in swipe samples successfully. The analysis results of uranium-bearing particles in swipe samples accorded with the operation history of the origin. - Highlights: • The developed method was successfully applied in the analysis of real swipe sample. • Uranium-bearing particles were confined in the middle of track detector. • The fission tracks of collodion film and PC film could be confirmed each other. • The thickness of collodion film should be no more than about 60 μm. • The method could avoid losing uranium-bearing particles in the etching step.

A study on compliant layers and its influence on dynamic response of a hydrodynamic journal bearing

DEFF Research Database (Denmark)

Thomsen, Kim; Klit, Peder

2011-01-01

For some hydrodynamic bearing applications polymer-lined bearings are chosen over traditional metal alloy bearings due to their better wear and friction properties when operating at very thin films, e.g. in the mixed lubrication region. The introduction of a compliant layer also affects the dynamic...... used to evaluate hydrodynamic bearing designs: dynamic response, maximum pressure, minimum film thickness, wear, power loss and temperature response. The primary findings are that the maximum pressures are reduced significantly and this comes at the expense of slightly higher eccentricity ratios during...

Design Optimization of Tilting-Pad Journal Bearing Using a Genetic Algorithm

Directory of Open Access Journals (Sweden)

Hamit Saruhan

2004-01-01

Full Text Available This article focuses on the use of genetic algorithms in developing an efficient optimum design method for tilting pad bearings. The approach optimizes based on minimum film thickness, power loss, maximum film temperature, and a global objective. Results for a five tilting-pad preloaded bearing are presented to provide a comparison with more traditional optimum design methods such as the gradient-based global criterion method, and also to provide insight into the potential of genetic algorithms in the design of rotor bearings. Genetic algorithms are efficient search techniques based on the idea of natural selection and genetics. These robust methods have gained recognition as general problem solving techniques in many applications.

Study about the influence of cavitation on the dynamic characteristics for the sliding bearing

International Nuclear Information System (INIS)

Zhai, L M; Luo, Y Y; Wang, Z W

2015-01-01

Sliding bearings are employed to support the rotor system and limit the vibration amplitude. In high speed rotor system, cavitation often occurs in the oil film and affects the dynamic characteristics of the sliding bearing greatly. In this paper, numerical method is adopted to simulate the cavitation in the oil film with homogeneous two-phase mixture flow using Singhal-et-al cavitation model in the commercial code FLUENT-solver. Cases without cavitation model were also calculated at the same time. Many computations with different frequency ratios were conducted. Then the rotor dynamic characteristics of the sliding bearing were retrieved. The results show that the cavitation has great influences on the pressure distribution in the oil film. As the rotational speed or whirling speed of the journal increases, the cavitation will become prominent. The dynamic coefficients of the bearing such as stiffness and damping with cavitation model considered are quite different from that without cavitation. So it is worth to pay attention to and do further study about the cavitation in the sliding bearing in the high speed rotor system

Numerical Modelling and Analysis of Hydrostatic Thrust Air Bearings for High Loading Capacities and Low Air Consumption

Science.gov (United States)

Yu, Yunluo; Pu, Guang; Jiang, Kyle

2017-12-01

The paper presents a numerical simulation study on hydrostatic thrust air bearings to assess the load capacity, compressed air consumptions, and the dynamic response. Finite Difference Method (FDM) and Finite Volume Method (FVM) are combined to solve the non-linear Reynolds equation to find the pressure distribution of the air bearing gas film and the total loading capacity of the bearing. The influence of design parameters on air film gap characteristics, including the air film thickness, supplied pressure, depth of the groove and external load, are investigated based on the proposed FDM model. The simulation results show that the thrust air bearings with a groove have a higher load capacity and air consumption than without a groove, and the load capacity and air consumption both increase with the depth of the groove. Bearings without the groove are better damped than those with the grooves, and the stability of thrust bearing decreases when the groove depth increases. The stability of the thrust bearings is also affected by their loading.

Active lubrication applied to internal combustion engines - evaluation of control strategies

DEFF Research Database (Denmark)

Estupinan, Edgar Alberto; Santos, Ilmar

2009-01-01

surface. The behaviour of a main bearing of a medium size combustion engine, operating with radial oil injection and with four different control strategies is analyzed, giving some insights into the minimum fluid film thickness, maximum fluid film pressure, friction losses and maximum vibration levels...... of reducing friction losses and vibrations between the crankshaft and the bearings. The conventional hydrodynamic lubrication is combined with hydrostatic lubrication which is actively modified by radially injecting oil at controllable pressures, through orifices circumferentially located around the bearing...

Comparison of Models for the Steady-State Analysis of Tilting-Pad Thrust Bearings

DEFF Research Database (Denmark)

Heinrichson, Niels; Santos, Ilmar

2005-01-01

Prediction of the minimum oil film thickness and the maximum temperature on the surface of the bearing pad is crucial in the design and dimensioning of bearings. Friction loss, oil bath temperature and pad deflection are other parameters of interest. Depending on the desired information a numerical...... for the groove between pads and the oil bath temperature from energy equilibrium for the entire bearing. The main theoretical contribution of this paper is the elaboration and comparison of 7 different mathematical models of increasing complexity. The results are compared to experimental data for steady......-state operation of a 228 mm outer diameter bearing. It is found that for the given bearing a two dimensional model is sufficient to estimate the minimum oil film thickness and the maximum temperature on the pad surface. Three dimensional modelling does not improve the quality of the results....

Intra-slab COH fluid fluxes evidenced by fluid-mediated decarbonation of lawsonite eclogite-facies altered oceanic metabasalts

Science.gov (United States)

Vitale Brovarone, Alberto; Chu, Xu; Martin, Laure; Ague, Jay J.; Monié, Patrick; Groppo, Chiara; Martinez, Isabelle; Chaduteau, Carine

2018-04-01

The interplay between the processes controlling the mobility of H2O and C-bearing species during subduction zone metamorphism exerts a critical control on plate tectonics and global volatile recycling. Here we present the first study on fresh, carbonate-bearing, lawsonite eclogite-facies metabasalts from Alpine Corsica, France, which reached the critical depths at which important devolatilization reactions occur in subducting slabs. The studied samples indicate that the evolution of oceanic crustal sequences subducted under present-day thermal regimes is dominated by localized fluid-rock interactions that are strongly controlled by the nature and extent of inherited (sub)seafloor hydrothermal processes, and by the possibility of deep fluids to be channelized along inherited or newly-formed discontinuities. Fluid channelization along inherited discontinuities controlled local rehydration and dehydration/decarbonation reactions and the stability of carbonate and silicate minerals at the blueschist-eclogite transition. Fluid-mediated decarbonation was driven by upward, up-temperature fluid flow in the inverted geothermal gradient of a subducting oceanic slab, a process that has not been documented in natural samples to date. We estimate that the observed fluid-rock reactions released 20-60 kg CO2 per m3 of rock (i.e. 0.7-2.1 wt% CO2), which is in line with the values predicted from decarbonation of metabasalts in open systems at these depths. Conversely, the estimated time-integrated fluid fluxes (20-50 t/m2) indicate that the amount of carbon transported by channelized fluid flow within the volcanic part of subducting oceanic plates is potentially much higher than previous numerical estimates, testifying to the percolation of C-bearing fluids resulting from devolatilization/dissolution processes operative in large reservoirs.

Analysis of hopanes and steranes in single oil-bearing fluid inclusions using time-of-flight secondary ion mass spectrometry (ToF-SIMS).

Science.gov (United States)

Siljeström, S; Lausmaa, J; Sjövall, P; Broman, C; Thiel, V; Hode, T

2010-01-01

Steranes and hopanes are organic biomarkers used as indicators for the first appearance of eukaryotes and cyanobacteria on Earth. Oil-bearing fluid inclusions may provide a contamination-free source of Precambrian biomarkers, as the oil has been secluded from the environment since the formation of the inclusion. However, analysis of biomarkers in single oil-bearing fluid inclusions, which is often necessary due to the presence of different generations of inclusions, has not been possible due to the small size of most inclusions. Here, we have used time-of-flight secondary ion mass spectrometry (ToF-SIMS) to monitor in real time the opening of individual inclusions trapped in hydrothermal veins of fluorite and calcite and containing oil from Ordovician source rocks. Opening of the inclusions was performed by using a focused C(60)(+) ion beam and the in situ content was precisely analysed for C(27)-C(29) steranes and C(29)-C(32) hopanes using Bi(3)(+) as primary ions. The capacity to unambiguously detect these biomarkers in the picoliter amount of crude oil from a single, normal-sized (15-30 mum in diameter) inclusion makes the approach promising in the search of organic biomarkers for life's early evolution on Earth.

A Three-Dimensional Foil Bearing Performance Map Applied to Oil-Free Turbomachinery

Science.gov (United States)

2009-04-01

stress brought on by excessive viscous power loss; therefore a map that graphically relates component and system-level parameters (bearing size, applied...Introduction Foil bearings are self-acting, hydrodynamic gas bearings that use air as their working fluid . Their use in rotating systems eliminates the...weight, maintenance requirements, speed, and temperature limitations associated with conventional oil-lubricated rotor supports (i.e., bearings, dampers

Rheological Properties of Quasi-2D Fluids in Microgravity

Science.gov (United States)

Stannarius, Ralf; Trittel, Torsten; Eremin, Alexey; Harth, Kirsten; Clark, Noel; Maclennan, Joseph; Glaser, Matthew; Park, Cheol; Hall, Nancy; Tin, Padetha

2015-01-01

In recent years, research on complex fluids and fluids in restricted geometries has attracted much attention in the scientific community. This can be attributed not only to the development of novel materials based on complex fluids but also to a variety of important physical phenomena which have barely been explored. One example is the behavior of membranes and thin fluid films, which can be described by two-dimensional (2D) rheology behavior that is quite different from 3D fluids. In this study, we have investigated the rheological properties of freely suspended films of a thermotropic liquid crystal in microgravity experiments. This model system mimics isotropic and anisotropic quasi 2D fluids [46]. We use inkjet printing technology to dispense small droplets (inclusions) onto the film surface. The motion of these inclusions provides information on the rheological properties of the films and allows the study of a variety of flow instabilities. Flat films have been investigated on a sub-orbital rocket flight and curved films (bubbles) have been studied in the ISS project OASIS. Microgravity is essential when the films are curved in order to avoid sedimentation. The experiments yield the mobility of the droplets in the films as well as the mutual mobility of pairs of particles. Experimental results will be presented for 2D-isotropic (smectic-A) and 2D-nematic (smectic-C) phases.

Analysis of wear of antifriction bearing using radioisotope method

International Nuclear Information System (INIS)

Bejcek, V.

1986-01-01

The time course was studied of the wear of one type of antifriction bearing in dependence on the thickness of lubricating film for five types of lubricating oil. The theory is described of the development of lubricating film, the experiment and its evaluation, and a detailed list is given of numerical results and practical conclusions. Briefly mentioned is the principle of the radioisotope method which has been described elsewhere: prior to the experiment the balls of the bearing were activated with a neutron beam from a nuclear reactor and the wear was determined from the activity of the worn material carried away by the lubricant. (A.K.)

Investigation of film flow of a conducting fluid in a transverse magnetic field, (1)

International Nuclear Information System (INIS)

Oshima, Shuzo; Yamane, Ryuichiro; Mochimaru, Yoshihiro; Sudo, Kouzo.

1985-01-01

Accompanying the development of large electromagnetic pumps transporting liquid metals used as the heat transfer media for nuclear power plants and the electromagnetic flow meters of large capacity, many researches have been carried out on the flow of liquid metals under the action of magnetic field. The utilization of electromagnetic force for continuous casting facilities seems very effective for the total processes from refining to solidification. Hereafter, it will be a technologically important problem to clarify the behavior of electro-conductive fluid with free surface under the action of magnetic field concerning the non-contact control of the interface form of molten metals as well as the cooling problem in nuclear fusion reactors. In this study, first the flow phenomena of MHD liquid film flow in a magnetic field with intensity gradient was analytically examined, and the effect of magnetic field gradient exerted on liquid film thickness and liquid surface form was clarified. Next, the experiment using mercury was carried out. For liquid film flow, magnetic field gradient acted as a kind of non-contact weir. (Kako, I.)

The Development of A Squeeze Film Damper Parametric Model in the Context of a Fluid-structural Interaction Task

Science.gov (United States)

Novikov, Dmitrii K.; Diligenskii, Dmitrii S.

2018-01-01

The article considers the work of some squeeze film damper with elastic rings parts. This type of damper is widely used in gas turbine engines supports. Nevertheless, modern analytical solutions have a number of limitations. The article considers the behavior of simple hydrodynamic damping systems. It describes the analysis of fluid-solid interaction simulation applicability for the defying properties of hydrodynamic damper with elastic rings (“allison ring”). There are some recommendations on the fluid structural interaction analysis of the hydrodynamic damper with elastic rings.

Capillary bending of a thin polymer film floating on a liquid bath

Science.gov (United States)

Twohig, Timothy; Croll, Andrew B.

Thin elastic films and shells are very important in schemes for the encapsulation and protection of fluids from their environment. Capillary origami is a particularly poignant example of how useful fluid/film structures can be formed. The interactions of fluids on thin-films which themselves lie on another surface (fluid or low friction solid) need to be studied if the differences from fluid-fluid and fluid-solid film interfaces are to be fully appreciated. In this experiment, we examine the triple line that occurs when a fluid is resting on a thin polymer film which is itself floating on a second fluid. The top fluid has a high-energy air/fluid interface which can be minimized by deforming the film in a manner that reduces the total air/fluid interface. We create a one-dimensional experiment in order to isolate the basic physics that occurs as the tension of the top fluid pulls on the thin film. Notably, the 1D geometry removes all the complexity incurred by thin films in biaxial stress states (such as wrinkling, folding and crumpling) from the problem. AFOSR under the Young Investigator Program (FA9550-15-1-0168).

Method of making supercritical fluid molecular spray films, powder and fibers

Science.gov (United States)

Smith, Richard D.

1988-01-01

Solid films are deposited, or fine powders formed, by dissolving a solid material into a supercritical fluid solution at an elevated pressure and then rapidly expanding the solution through a heated nozzle having a short orifice into a region of relatively low pressure. This produces a molecular spray which is directed against a substrate to deposit a solid thin film thereon, or discharged into a collection chamber to collect a fine powder. In another embodiment, the temperature of the solution and nozzle is elevated above the melting point of the solute, which is preferably a polymer, and the solution is maintained at a pressure such that, during expansion, the solute precipitates out of solution within the nozzle in a liquid state. Alternatively, a secondary solvent mutually soluble with the solute and primary solvent and having a higher critical temperature than that of primary solvent is used in a low concentration (<20%) to maintain the solute in a transient liquid state. The solute is discharged in the form of long, thin fibers. The fibers are collected at sufficient distance from the orifice to allow them to solidify in the low pressure/temperature region.

Entropy generation in non-Newtonian fluid flow in a slider bearing

Indian Academy of Sciences (India)

In the present study, entropy production in flow fields due to slider bearings is formulated. The rate of entropy generation is computed for different fluid properties and geometric configurations of the slider bearing. In order to account for the non-Newtonian effect, a special type of third-grade fluid is considered. It is found that ...

Improvement of Thrust Bearing Calculation Considering the Convectional Heating within the Space between the Pads

OpenAIRE

Monika Chmielowiec-Jablczyk; Andreas Schubert; Christian Kraft; Hubert Schwarze; Michal Wodtke; Michal Wasilczuk

2018-01-01

A modern thrust bearing tool is used to estimate the behavior of tilting pad thrust bearings not only in the oil film between pad and rotating collar, but also in the space between the pads. The oil flow in the space significantly influences the oil film inlet temperature and the heating of pad and collar. For that reason, it is necessary to define an oil mixing model for the space between the pads. In the bearing tool, the solutions of the Reynolds equation including a cavitation model, the ...

The solubility of thorium and uranium from respirable monazite bearing dust in simulated lung and gut fluids

International Nuclear Information System (INIS)

Twining, J.; McGlinn, P.; Hart, K.

1993-01-01

The accurate assessment of the radiological dose to workers in the mineral sands industry requires information on the human bio-availability of thorium and uranium from monazite bearing respirable dust. The results of a short-term test to determine some of the solubility characteristics of these radionuclides are presented, together with a discussion on the optimum methods which may be applied to longer term studies. The solubility of thorium and uranium were found to be generally less than that of the parent monazite bearing dust in simulated lung and gut fluids over the one month extraction period. In particular, thorium was up to two orders of magnitude less soluble than its host mineral matrix. Assuming that the conservative nature of these radioactive constituents can be extrapolated to longer term exposures, these results imply that radiological dose estimates to the lung should be increased. Solubility of both elements was proportional to particle size. An exponential increase in solubility with decreasing diameter was observed, which implies a time variable solubility. There was also some indication of preferential solubility of radium progeny in both decay series. These factors may have to be accounted for in model estimates of committed dose. 16 refs., 4 tabs., 2 figs

Measurement and calculation of dynamic coefficients in hydrodynamic bearings of gas films; Medicion y calculo de coeficientes dinamicos en cojinetes hidrodinamicos de peliculas de gas

Energy Technology Data Exchange (ETDEWEB)

Ruiz, Rafael O.; Di Liscia, Marcelo H.; Diaz, Sergio E. [Universidad Simon Bolivar, Sartendejas, Baruta (Venezuela)

2007-11-15

The identification of the dynamic coefficients in air bearings is fundamental for a suitable roto-dynamic analysis. The present paper shows the development of an algorithm that allows the direct obtaining of the dynamic coefficients in hydrodynamic air bearings as much of numerical form as experimental. The testing bench used consists of two magnetic bearings, which support the rotor in their ends and work as well as actuators allowing inducing controlled orbits in the rotor. The test bearing is located between the magnetic bearings. The dynamic forces generated in the air bearing are registered from three load cells. The algorithm was developed in a commercial code of graphical programming, through which the signals can be collected, controlled and processed. The nonlinear behavior of this type of bearings makes difficult the calculation of the dynamic coefficients, therefore the processing of the signals in frequencial space facilitates, in a certain way, its handling. On the other hand, the numerical model was compared with the experimental results obtaining acceptable approaches in magnitude as well as in behavior. The numerical dynamic coefficients calculation was realized solving the Reynolds differential equation for a compressible fluid in the thickness of the gas film, taking into consideration the fluid mass flow that is introduced, as well as the pressure loss suffered by the same in passing through the feeding orifices. The numerical methods utilized include the solution of the differential equation of Reynolds for finite differences, the calculation of the profile realizing successive iterations and the calculation of the hydrodynamics forces through the Simpson numerical integration. The numerical dynamic coefficients were found applying a minimum squared technique to the hydrodynamic stresses generated in simulating an orbit of the rotor at a determined frequency and velocity, allowing in this way the calculation of the synchronous and asynchronous

Evaluation of the Thermal Effects in Tilting Pad Bearing

Directory of Open Access Journals (Sweden)

G. B. Daniel

2013-01-01

Full Text Available The analysis of thermal effects is of expressive importance in the context of rotordynamics to evaluate the behavior of hydrodynamic bearings because these effects can influence their dynamic characteristics under specific operational conditions. For this reason, a thermohydrodynamic model is developed in this work, in which the pressure distribution in the oil film and the temperature distribution are calculated together. From the pressure distribution, the velocity distribution field is determined, as well as the viscous dissipation, and consequently, the temperature distribution. The finite volume method is applied to solve the Reynolds equation and the energy equation in the thermohydrodynamic model (THD. The results show that the temperature is higher as the rotational speed increases due to the shear rate of the oil film. The maximum temperature in the bearing occurs in the overloaded pad, near the outlet boundary. The experimental tests were performed in a tilting pad journal bearing operating in a steam turbine to validate the model. The comparison between the experimental and numerical results provides a good correlation. The thermohydrodynamic lubrication developed in this assignment is promising to consistently evaluate the behavior of the tilting pad journal bearing operating in relatively high rotational speeds.

Dynamic behavior of hybrid sodium bearings. Theoretical and experimental studies

International Nuclear Information System (INIS)

Guidez, J.; Juignet, N.; Queval, M.

1981-08-01

The primary sodium pump shaft lower section of a fast breeder reactor is guided by a hydrostatic sodium bearing. This recess type bearing is supplied via orifices restrictors. Sodium is sampled at hight pressure at the diffuser outlet and is then centrifuged towards the orifices restrictors. Bearing stiffness and damping data is essential for the study of rotor dynamic behavior. Two points in particular may then be studied: - calculation of rotor instability ranges and critical speeds, - dynamic behavior of the rotor in the event of an earthquake. As regards the bearing design, the problem is to obtain the pressure fields in the liquid film. The integration of these pressure fields will then give the stiffness coefficients. The damping coefficients can then be obtained by the same calculation after slight displacement. The Reynolds equation can be used to study the liquid film (under any conditions for the turbulent and inertia effects). Then the computer code DELPAL is explained that solves the modified Reynolds equation using a finite element method. The presentation of tests conducted in 1981 on the Super-Phenix 1 full scall bearing (diameter 850 mm) in water is made. In conclusion this paper describes a method for calculating the stiffness and damping matrices of a hydrostatic bearing using the DELPAL calculation code and shows the loop of behavior tests on a bearing with sinusoidal excitation. The results, obtained by calculation and by testing, are indispensable when calculating the dynamic behavior of the shaft line

Superconducting bearings for a LHe transfer pump

Science.gov (United States)

Kloeppel, S.; Muehsig, C.; Funke, T.; Haberstroh, C.; Hesse, U.; Lindackers, D.; Zielke, S.; Sass, P.; Schoendube, R.

2017-12-01

Superconducting bearings are used in a number of applications for high speed, low loss suspension. Most of these applications suspend a warm shaft and thus require continuous cooling, which leads to additional power consumption. Therefore, it seems advantageous to use these bearings in systems that are inherently cold. One respective application is a submerged pump for the transfer of liquid helium into mobile dewars. Centrifugal pumps require tight sealing clearances, especially for low viscosity fluids and small sizes. This paper covers the design and qualification of superconducting YBCO bearings for a laboratory sized liquid helium transfer pump. Emphasis is given to the axial positioning, which strongly influences the achievable volumetric efficiency.

On the normal stress effect in grease-lubricated bearing seals

NARCIS (Netherlands)

Baart, P.; Lugt, Pieter Martin; Prakash, B.

2014-01-01

The film formation in lip seals, due to the non-Newtonian rheology of the lubricant, has been a topic of speculation. Earlier work suggests that normal stresses in grease would be favorable for the film buildup between the seal lip and shaft or bearing ring. In the current article, we evaluate this

Measuring fluid pressure

International Nuclear Information System (INIS)

Lee, A.S.

1978-01-01

A method and apparatus are described for measuring the pressure of a fluid having characteristics that make it unsuitable for connection directly to a pressure gauge. The method is particularly suitable for the periodic measurement of the pressure of a supply of liquid Na to Na-lubricated bearings of pumps for pumping Na from a reservoir to the bearing via a filter, the reservoir being contained in a closed vessel containing an inert blanket gas, such as Ar, above the Na. (UK)

Remote query measurement of pressure, fluid-flow velocity, and humidity using magnetoelastic thick-film sensors

Science.gov (United States)

Grimes, C. A.; Kouzoudis, D.

2000-01-01

Free-standing magnetoelastic thick-film sensors have a characteristic resonant frequency that can be determined by monitoring the magnetic flux emitted from the sensor in response to a time varying magnetic field. This property allows the sensors to be monitored remotely without the use of direct physical connections, such as wires, enabling measurement of environmental parameters from within sealed, opaque containers. In this work, we report on application of magnetoelastic sensors to measurement of atmospheric pressure, fluid-flow velocity, temperature, and mass load. Mass loading effects are demonstrated by fabrication of a remote query humidity sensor, made by coating the magnetoelastic thick film with a thin layer of solgel deposited Al2O3 that reversibly changes mass in response to humidity. c2000 Elsevier Science S.A. All rights reserved.

Interferometric characterization of tear film dynamics

Science.gov (United States)

Primeau, Brian Christopher

The anterior refracting surface of the eye is the thin tear film that forms on the surface of the cornea. When a contact lens is on worn, the tear film covers the contact lens as it would a bare cornea, and is affected by the contact lens material properties. Tear film irregularity can cause both discomfort and vision quality degradation. Under normal conditions, the tear film is less than 10 microns thick and the thickness and topography change in the time between blinks. In order to both better understand the tear film, and to characterize how contact lenses affect tear film behavior, two interferometers were designed and built to separately measure tear film behavior in vitro and in vivo. An in vitro method of characterizing dynamic fluid layers applied to contact lenses mounted on mechanical substrates has been developed using a phase-shifting Twyman-Green interferometer. This interferometer continuously measures light reflected from the surface of the fluid layer, allowing precision analysis of the dynamic fluid layer. Movies showing this fluid layer behavior can be generated. The fluid behavior on the contact lens surface is measured, allowing quantitative analysis beyond what typical contact angle or visual inspection methods provide. The in vivo interferometer is a similar system, with additional modules included to provide capability for human testing. This tear film measurement allows analysis beyond capabilities of typical fluorescein visual inspection or videokeratometry and provides better sensitivity and resolution than shearing interferometry methods.

Experimental test of static and dynamic characteristics of tilting-pad thrust bearings

OpenAIRE

Annan Guo; Xiaojing Wang; Jian Jin; Diann Y Hua; Zikai Hua

2015-01-01

The axial vibration in turbine machine has attracted more and more interest. Tilting-pad thrust bearings are widely used in turbine machines to support the axial load. The dynamic properties generated by oil film of the thrust pad have important effects on the axial vibration of the rotor-bearing system. It is necessary to develop the method to test the dynamic characteristics of thrust bearings. A new rig has been developed. The facility allows a complete set of bearing operating parameters ...

Ideal glass transitions in thin films: An energy landscape perspective

Science.gov (United States)

Truskett, Thomas M.; Ganesan, Venkat

2003-07-01

We introduce a mean-field model for the potential energy landscape of a thin fluid film confined between parallel substrates. The model predicts how the number of accessible basins on the energy landscape and, consequently, the film's ideal glass transition temperature depend on bulk pressure, film thickness, and the strength of the fluid-fluid and fluid-substrate interactions. The predictions are in qualitative agreement with the experimental trends for the kinetic glass transition temperature of thin films, suggesting the utility of landscape-based approaches for studying the behavior of confined fluids.

An experimental study on oil supply in a space bearing with an oil-impregnated retainer

Science.gov (United States)

Liu, Jianhai; Fan, Youwen; Wen, Shizhu

1993-06-01

Parched elastohydrodynamic lubrication (EHL) film thickness in a space ball bearing is measured by electrical capacitance and resistance, and parched transients of oil film and lubricant breakdown are observed. With different oil-impregnated polymer retainers, which are employed as oil supply resources, parched degradation is restricted to some degree, even lubricant breakdown disappears and a steady state of the oil film is produced. A long-term space bail bearing demands both the lowest driving torque and a steady state oil film, which depends on a strictly controlled oil supply from oil-impregnated retainers. The results of this experimental research describe the effects of oil supply by amounts of oil in retainers on parched EHL.

Analysis of thin film flow over a vertical oscillating belt with a second grade fluid

Directory of Open Access Journals (Sweden)

Taza Gul

2015-06-01

Full Text Available An analysis is performed to study the unsteady thin film flow of a second grade fluid over a vertical oscillating belt. The governing equation for velocity field with appropriate boundary conditions is solved analytically using Adomian decomposition method (ADM. Expressions for velocity field have been obtained. Optimal asymptotic method (OHAM has also been used for comparison. The effects of Stocks number, frequency parameter and pressure gradient parameters have been sketched graphically and discussed.

Connection Between Thermodynamics and Dynamics of Simple Fluids in Pores: Impact of Fluid-Fluid Interaction Range and Fluid-Solid Interaction Strength.

Science.gov (United States)

Krekelberg, William P; Siderius, Daniel W; Shen, Vincent K; Truskett, Thomas M; Errington, Jeffrey R

2017-08-03

Using molecular simulations, we investigate how the range of fluid-fluid (adsorbate-adsorbate) interactions and the strength of fluid-solid (adsorbate-adsorbent) interactions impact the strong connection between distinct adsorptive regimes and distinct self-diffusivity regimes reported in [Krekelberg, W. P.; Siderius, D. W.; Shen, V. K.; Truskett, T. M.; Errington, J. R. Langmuir 2013 , 29 , 14527-14535]. Although increasing the fluid-fluid interaction range changes both the thermodynamics and the dynamic properties of adsorbed fluids, the previously reported connection between adsorptive filling regimes and self-diffusivity regimes remains. Increasing the fluid-fluid interaction range leads to enhanced layering and decreased self-diffusivity in the multilayer-formation regime but has little effect on the properties within film-formation and pore-filling regimes. We also find that weakly attractive adsorbents, which do not display distinct multilayer formation, are hard-sphere-like at super- and subcritical temperatures. In this case, the self-diffusivity of the confined and bulk fluid has a nearly identical scaling-relationship with effective density.

Drag reduction and improvement of material transport in creeping films

Energy Technology Data Exchange (ETDEWEB)

Scholle, M.; Rund, A.; Aksel, N. [University of Bayreuth, Department of Applied Mechanics and Fluid Dynamics, Bayreuth (Germany)

2006-01-01

It is widely accepted that for bodies in turbulent flows a reduction of skin friction can be reached if the surface of the body is provided with small ridges aligned in the local flow direction. This surprising and counterintuitive phenomenon is called the shark-skin effect, motivated from the dermal surface morphology of sharks. In the present article we examine the possibility of resistance reduction due to a rippled surface topography in Stokes flow. We especially analyse the influence of wall riblets perpendicular to the flow direction on the mean transport velocity in gravity-driven creeping film flows following the idea that eddies generated in the valleys of the riblets act like fluid roller bearings and hence may reduce drag. Using a theoretical treatment of the Stokes equations with complex function theory, parameter studies with varying flow rate, bottom amplitude and bottom shape are presented. For the given bottom shapes the maximum enhancement of transport velocity is found by optimising the film thickness. (orig.)

Testing of Bearing Materials for Large Two-stroke Marine Diesel Engines

DEFF Research Database (Denmark)

Klit, Peder; Persson, Sebastian; Vølund, Anders

2013-01-01

In large two-stroke marine diesel engines bearings are designed with the intention that these need not be replaced during the life of the engine. The design has shown very good service experiences. The design parameters of the main bearings are, among others, based on the average maximum specific...... load which the bearing should operate under. In general, the frictional loss is less than 1% of the nominal power of the engine but is still a target for optimization. Fatigue mechanisms of bearing lining material are not fully understood and the design limits with regards to minimum oil film thickness...

On almost inviscid film flows

NARCIS (Netherlands)

Kuiken, H.K.

1970-01-01

This study is concerned with flow of liquid films down inclined plates, which carry an increasing amount of fluid in the downstream direction. It is supposed that by some mechanism, e.g. condensation, the fluid enters the film at its outer edge. The rate at which this mass-addition occurs is

Performance Improvement of tilting-pad journal bearings by means of controllable lubrication

DEFF Research Database (Denmark)

Cerda, Alejandro; Santos, Ilmar

2012-01-01

Tilting-Pad Journal Bearings (TPJB) are commonly used on high-performance turbomachinery due to their excellent stability properties at high speed when compared to other designs for oil film bearings. Hence, efforts have been made to improve the accuracy for the available models for these mechani...... is used to show the benefits of applying a controllable lubrication regime, by means of the modification of the thermal and dynamic behaviour of the bearing....

Application of hydrophilic magnetic fluid to oil seal

Science.gov (United States)

Kim, Y. S.; Nakatsuka, K.; Fujita, T.; Atarashi, T.

1999-07-01

Bearing and gear are important components in machines. Lubricant for bearing or gear is usually confined in working space by rubber retainer or mechanical seal, and its lifetime which is determined by the friction wear of sealing material is important. In this report, the basic characteristics of magnetic fluid seal applied to lubricant retainer is studied. The fluid used for this purpose is ethyleneglycol-based magnetic fluid in which silica-coated iron particles are dispersed. The lubricant oil seal set consisting of six stages of pole piece and Nd-permanent magnets (4.0 Wb/m 2) in seal housing showed an excellent pressure resistance of 618 kPa under a rotating speed of 1800 rpm.

Topological Fluid Mechanics with Applications to Free Surfaces and Axisymmetric Flows

DEFF Research Database (Denmark)

Brøns, Morten

1996-01-01

Topological fluid mechanics is the study of qualitative features of fluid patterns. We discuss applications to the flow beneath a stagnant surface film, and to patterns in axisymmetric flow.......Topological fluid mechanics is the study of qualitative features of fluid patterns. We discuss applications to the flow beneath a stagnant surface film, and to patterns in axisymmetric flow....

Effect of oil around the pin boss bearing on bearing friction force; Piston pin jikuukebu kinbo no junkatsuyu ga masatsuryoku ni oyobosu eikyo

Energy Technology Data Exchange (ETDEWEB)

Takiguchi, M; Suhara, T; Ato, S; Someya, T [Musashi Institute of Technology, Tokyo (Japan)

1997-10-01

Piston pin bearings are engine parts placed under severe lubricating condition because of the high unit load and temperature and the low sliding speeds. Therefore, they are vulnerable to many lubrication problems such as abnormal wear, scuffs and seizures. In our recent study, the bearing friction were measured using a original measuring device and it was found out that the lubricating conditions of piston pin boss bearings are non-fluid lubrication due to the oil starvation. In this study, we have also measured the lubricating oil behavior around the pin boss bearing using a special cylinder with glass window, and analyzed the relationship between the friction force and the oil behavior at the pin boss bearings in a actual operating gasoline engine. 2 refs., 9 figs., 1 tab.

[Correlative analysis on metatarsalgia and the X-ray measurement indexes under weight-bearing and non-weight-bearing of hallux valgus].

Science.gov (United States)

Gong, Hao; Sang, Zhi-Cheng; Wen, Jian-Min; Sun, Wei-Dong; Hu, Hai-Wei; Zhang, Yong-Chao; Zuo, Jian-Gang; Wang, Hai-Xiong

2014-04-01

To study changes in the radiographic appearance during weight-bearing and non-weigh-bearing in hallux valgus, and to analyse the correlation between the elasticity of plantar soft tissue of hallux valgus and the pain under the metatarsal head. From May 2012 to October 2012, 240 feet of 120 patients with hallux valgus were enrolled in the study. The degrees of the pian under the metatarsal head of all the patients were observed. AP and lateral X-ray films of feet were taken on the condition of weight-bearing and non-weight-bearing. So the hallux valgus angle (HVA), the inter-metatarsal angle between the first and second metatarsals (IM1-2), the inter-metatarsal angle between the first and fifth metatarsals (IM1-5), top angle of the medial longitudinal arch (TAOTMLA),and anterior angle of the medial longitudinal arch (AAOTMLA) were measured on the X-ray films. The differences of HVA, IM1-2, IM1-5, TAOTMLA and AAOTMLA between two groups were compared, and the correlation between the changes of IM1-2, IM 1-5, TAOTMLA, AAOTMLA and the degree of the pain under the metatarsal head were analysed. One hundred and forty-eight feet had the pain under the metatarsal head. The IM1-2, IM1-5 and TAOTMLA increased on weight-bearing position compared with those on non-weight-bearing position, but the HVA and AAOTMLA decreased on weight-bearing position compared with those on non-weight-bearing position. There was a moderate relationship between the changes of IM 1-2,IM1-5 and the degree of the hallux valgus deformity, as well as the relationship between the different of IM1-5 and the degree of the pian under the metatarsal head. The degree of the collapse of the arch of foot with hallux valgus becomes serious with its deformity increasing. The pain under the metatarsal head of hallux valgus increases with the increased changes of IM 1-2,IM 1-5 and TAOTMLA. Analysis of the X-ray observation indexes of hallux valgus on weight-bearing position and non-weight-bearing position has

Magmatic nature of Sn-bearing fluids from isotopic (H,O) data of tourmalines (Solnechnoye deposit, Far East of Russia)

Science.gov (United States)

Sushchevskaya, Tatiana; Ignatiev, Alexander; Velivetskaya, Tatiana

2010-05-01

It was shown, that the main factors, controlled Sn-W ore deposition in hydrothermal systems in connection with granites were: a) cooling, b) mixing of fluids of different composition and genesis, c) heterogenization (boiling) of mineral forming fluids (Heinrich, 1990; et al). The results of physical chemical modelling of water-rock interaction pointed to magmatic nature of tin-bearing fluids in the hydrothermal systems, connected with granites. Tin concentration in model magmatogeneous fluid was calculated to be three times higher than in the model exogenic fluid (Sushchevskaya, Ryzhenko, 1998). New data on the source of ore forming fluids, which had formed the large economic Solnechnoye Sn deposit (Far East of Russia), were obtained from hydrogen and oxygen isotopic composition of tourmalines from successive mineral associations. Hydrogen position in the tourmaline crystal structure allows to suppose, that postproductive processes did not change the initial δD values, in contrast to phyllosilicates, often used for this purpose. During mineral formation at the Solnechnoye deposit tourmaline was formed practically without interruption. Its composition was gradually changed from schorl to dravite, when temperature decreased. The ores of cassiterite-tourmaline type were formed in a vertically dipping fracture zones, extended in a metamorphosed sandstone-shale rocks. Hydrogene and oxygen isotopic composition of fluids were calculated from tourmaline data with the help of equations, proposed in (Kotzer et al., 1993). The temperature intervals for these calculations were accepted as: 1- 450-400o C for quartz-tourmaline preore stage, 2 - 400-350o C -for early productive quartz-cassiterite stage, 3 - 350-300o C - for late quartz- cassiterite stage. The obtained results corresponded to magmatic character of the fluids of productive stage of the Solnechnoye deposit, because their isotopic composition lied in the interval: δ18О (3.2-9.3)‰, δD -(31.7-76.6)‰. The

Self-propagating exothermic reaction analysis in Ti/Al reactive films using experiments and computational fluid dynamics simulation

Energy Technology Data Exchange (ETDEWEB)

Sen, Seema, E-mail: seema.sen@tu-ilmenau.de [Technical University of Ilmenau, Department of Materials for Electronics, Gustav-Kirchhoff-Str. 5, 98693 Ilmenau (Germany); Niederrhein University of Applied Science, Department of Mechanical and Process Engineering, Reinarzstraße 49, 47805 Krefeld (Germany); Lake, Markus; Kroppen, Norman; Farber, Peter; Wilden, Johannes [Niederrhein University of Applied Science, Department of Mechanical and Process Engineering, Reinarzstraße 49, 47805 Krefeld (Germany); Schaaf, Peter [Technical University of Ilmenau, Department of Materials for Electronics, Gustav-Kirchhoff-Str. 5, 98693 Ilmenau (Germany)

2017-02-28

Highlights: • Development of nanoscale Ti/Al multilayer films with 1:1, 1:2 and 1:3 molar ratios. • Characterization of exothermic reaction propagation by experiments and simulation. • The reaction velocity depends on the ignition potentials and molar ratios of the films. • Only 1Ti/3Al films exhibit the unsteady reaction propagation with ripple formation. • CFD simulation shows the time dependent atom mixing and temperature flow during exothermic reaction. - Abstract: This study describes the self-propagating exothermic reaction in Ti/Al reactive multilayer foils by using experiments and computational fluid dynamics simulation. The Ti/Al foils with different molar ratios of 1Ti/1Al, 1Ti/2Al and 1Ti/3Al were fabricated by magnetron sputtering method. Microstructural characteristics of the unreacted and reacted foils were analyzed by using electronic and atomic force microscopes. After an electrical ignition, the influence of ignition potentials on reaction propagation has been experimentally investigated. The reaction front propagates with a velocity of minimum 0.68 ± 0.4 m/s and maximum 2.57 ± 0.6 m/s depending on the input ignition potentials and the chemical compositions. Here, the 1Ti/3Al reactive foil exhibits both steady state and unsteady wavelike reaction propagation. Moreover, the numerical computational fluid dynamics (CFD) simulation shows the time dependent temperature flow and atomic mixing in a nanoscale reaction zone. The CFD simulation also indicates the potentiality for simulating exothermic reaction in the nanoscale Ti/Al foil.

Multiple sulfur isotopes monitor fluid evolution of an Archean orogenic gold deposit

Science.gov (United States)

LaFlamme, Crystal; Sugiono, Dennis; Thébaud, Nicolas; Caruso, Stefano; Fiorentini, Marco; Selvaraja, Vikraman; Jeon, Heejin; Voute, François; Martin, Laure

2018-02-01

The evolution of a gold-bearing hydrothermal fluid from its source to the locus of gold deposition is complex as it experiences rapid changes in thermochemical conditions during ascent through the crust. Although it is well established that orogenic gold deposits are generated during time periods of abundant crustal growth and/or reworking, the source of fluid and the thermochemical processes that control gold precipitation remain poorly understood. In situ analyses of multiple sulfur isotopes offer a new window into the relationship between source reservoirs of Au-bearing fluids and the thermochemical processes that occur along their pathway to the final site of mineralisation. Whereas δ34S is able to track changes in the evolution of the thermodynamic conditions of ore-forming fluids, Δ33S is virtually indelible and can uniquely fingerprint an Archean sedimentary reservoir that has undergone mass independent fractionation of sulfur (MIF-S). We combine these two tracers (δ34S and Δ33S) to characterise a gold-bearing laminated quartz breccia ore zone and its sulfide-bearing alteration halo in the (+6 Moz Au) structurally-controlled Archean Waroonga deposit located in the Eastern Goldfields Superterrane of the Yilgarn Craton, Western Australia. Over 250 analyses of gold-associated sulfides yield a δ34S shift from what is interpreted as an early pre-mineralisation phase, with chalcopyrite-pyrrhotite (δ34S = +0.7‰ to +2.9‰) and arsenopyrite cores (δ34S = ∼-0.5‰), to a syn-mineralisation stage, reflected in Au-bearing arsenopyrite rims (δ34S = -7.6‰ to +1.5‰). This shift coincides with an unchanging Δ33S value (Δ33S = +0.3‰), both temporally throughout the Au-hosting hydrothermal sulfide paragenesis and spatially across the Au ore zone. These results indicate that sulfur is at least partially recycled from MIF-S-bearing Archean sediments. Further, the invariant nature of the observed MIF-S signature demonstrates that sulfur is derived from a

Survey of Damage Investigation of Babbitted Industrial Bearings

Directory of Open Access Journals (Sweden)

Lyle A. Branagan

2015-04-01

Full Text Available This survey collects the efforts to understand the sources and consequences of damage to babbitted industrial bearings, which operate by means of a hydrodynamic, or hydrostatic, film. Major individual damage types are discussed in the context of major damage categories.

Bearing development program for a 25 kWe solar-powered organic Rankine-cycle engine

Science.gov (United States)

Nesmith, B.

1985-01-01

The bearing development program is summarized for a 25-kWe power conversion subsystem (PCS) consisting of an organic Rankine-cycle engine, and permanent magnetic alternator (PMA) and rectifier to be used in a 100-kWe point-focusing distributed receiver solar power plant. The engine and alternator were hermetically sealed and used toluene as the working fluid. The turbine, alternator, and feed pump (TAP) were mounted on a single shaft operating at speeds up to 60,000 rev/min. Net thermal-to-electric efficiencies in the range of 21 to 23% were demonstrated at the maximum working fluid temperature of 400 C (750 F). A chronological summary of the bearing development program is presented. The primary causes of bearing wear problems were traced to a combination of rotordynamic instability and electrodynamic discharge across the bearing surfaces caused by recirculating currents from the PMA. These problems were resolved by implementing an externally supplied, flooded-bearing lubrication system and by electrically insulating all bearings from the TAP housing. This program resulted in the successful development of a stable, high-speed, toluene-lubricated five-pad tilting-pad journal bearing and Rayleigh step thrust bearing system capable of operating at all inclinations between horizontal and vertical.

Ideal glass transitions in thin films: An energy landscape perspective

OpenAIRE

Truskett, Thomas M.; Ganesan, Venkat

2003-01-01

We introduce a mean-field model for the potential energy landscape of a thin fluid film confined between parallel substrates. The model predicts how the number of accessible basins on the energy landscape and, consequently, the film's ideal glass transition temperature depend on bulk pressure, film thickness, and the strength of the fluid-fluid and fluid-substrate interactions. The predictions are in qualitative agreement with the experimental trends for the kinetic glass transition temperatu...

From Hybrid to Actively-Controlled Gas Lubricated Bearings – Theory and Experiment

DEFF Research Database (Denmark)

Morosi, Stefano

bearings, tilting pad and flexure pivot gas bearings. These solutions proved to be effective in improving static and dynamic properties of the bearings, however issues related to the manufacturing and accuracy of predictions has so far limited their applications. Another drawback is that passive bearings......-rig are backed by a comprehensive mathematical model that couples a finite element model of a flexible rotor, a thermohydrodynamic model based on a modified form of the Reynold’s equation for hybrid aerostatic-aerodynamic lubrication of compressible fluid, a piezoelectric injection system and a proportional...

60NiTi Intermetallic Material Evaluation for Lightweight and Corrosion Resistant Spherical Sliding Bearings for Aerospace Applications, Report on NASA-Kamatics SAA3-1288

Science.gov (United States)

Dellacorte, Christopher; Jefferson, Michael

2015-01-01

Under NASA Space Act Agreement (SAA3-1288), NASA Glenn Research Center and the Kamatics subsidiary of the Kaman Corporation conducted the experimental evaluation of spherical sliding bearings made with 60NiTi inner races. The goal of the project was to assess the feasibility of manufacturing lightweight, corrosion resistant bearings utilizing 60NiTi for aerospace and industrial applications. NASA produced the bearings in collaboration with Abbott Ball Corporation and Kamatics fabricated bearing assemblies utilizing their standard reinforced polymer liner material. The assembled bearings were tested in oscillatory motion at a load of 4.54 kN (10,000 lb), according to the requirements of the plain bearing specification SAE AS81820. Several test bearings were exposed to hydraulic fluid or aircraft deicing fluid prior to and during testing. The results show that the 60NiTi bearings exhibit tribological performance comparable to conventional stainless steel (440C) bearings. Further, exposure of 60NiTi bearings to the contaminant fluids had no apparent performance effect. It is concluded that 60NiTi is a feasible bearing material for aerospace and industrial spherical bearing applications.

Mantle wedge infiltrated with saline fluids from dehydration and decarbonation of subducting slab.

Science.gov (United States)

Kawamoto, Tatsuhiko; Yoshikawa, Masako; Kumagai, Yoshitaka; Mirabueno, Ma Hannah T; Okuno, Mitsuru; Kobayashi, Tetsuo

2013-06-11

Slab-derived fluids play an important role in heat and material transfer in subduction zones. Dehydration and decarbonation reactions of minerals in the subducting slab have been investigated using phase equilibria and modeling of fluid flow. Nevertheless, direct observations of the fluid chemistry and pressure-temperature conditions of fluids are few. This report describes CO2-bearing saline fluid inclusions in spinel-harzburgite xenoliths collected from the 1991 Pinatubo pumice deposits. The fluid inclusions are filled with saline solutions with 5.1 ± 1.0% (wt) NaCl-equivalent magnesite crystals, CO2-bearing vapor bubbles, and a talc and/or chrysotile layer on the walls. The xenoliths contain tremolite amphibole, which is stable in temperatures lower than 830 °C at the uppermost mantle. The Pinatubo volcano is located at the volcanic front of the Luzon arc associated with subduction of warm oceanic plate. The present observation suggests hydration of forearc mantle and the uppermost mantle by slab-derived CO2-bearing saline fluids. Dehydration and decarbonation take place, and seawater-like saline fluids migrate from the subducting slab to the mantle wedge. The presence of saline fluids is important because they can dissolve more metals than pure H2O and affect the chemical evolution of the mantle wedge.

Lubrication of Space Shuttle Main Engine Turbopump Bearings

Science.gov (United States)

Gibson, Howard; Munafo, Paul (Technical Monitor)

2001-01-01

The Space Shuttle has three main engines that are used for propulsion into orbit. These engines are fed propellants by four turbopumps on each engine. A main element in the turbopump is the bearings supporting the rotor that spins the turbine blades and the pump impeller. These bearings are required to spin at very high speeds, support radial and thrust loads, and have high wear resistance without the benefit of lubrication. The liquid hydrogen and oxygen propellants flow through the bearings to cool the surfaces. The volatile nature of the propellants excludes any conventional means of lubrication. Lubrication for these bearings is provided by the ball separator inside the bearing. The separator is a composite material that supplies a transfer film of lubrication to the rings and balls. New separator materials and lubrication schemes have been investigated at Marshall Space Flight Center in a bearing test rig with promising results. Hybrid bearings with silicon nitride balls have also been evaluated. The use of hybrid, silicon nitride ball bearings in conjunction -with better separator materials has shown excellent results. The work that Marshall has done is being utilized in turbopumps flying on the space shuttle fleet and will be utilized in future space travel. This result of this work is valuable for all aerospace and commercial applications where high-speed bearings are used.

Cell Adhesion and Proliferation on Sulfonated and Non-Modified Chitosan Films.

Science.gov (United States)

Martínez-Campos, Enrique; Civantos, Ana; Redondo, Juan Alfonso; Guzmán, Rodrigo; Pérez-Perrino, Mónica; Gallardo, Alberto; Ramos, Viviana; Aranaz, Inmaculada

2017-05-01

Three types of chitosan-based films have been prepared and evaluated: a non-modified chitosan film bearing cationizable aliphatic amines and two films made of N-sulfopropyl chitosan derivatives bearing both aliphatic amines and negative sulfonate groups at different ratios. Cell adhesion and proliferation on chitosan films of C2C12 pre-myoblastic cells and B16 cells as tumoral model have been tested. A differential cell behavior has been observed on chitosan films due to their different surface modification. B16 cells have shown lower vinculin expression when cultured on sulfonated chitosan films. This study shows how the interaction among cells and material surface can be modulated by physicochemical characteristics of the biomaterial surface, altering tumoral cell adhesion and proliferation processes.

Dynamic Performance Characteristics of a Curved Slider Bearing Operating with Ferrofluids

Directory of Open Access Journals (Sweden)

Udaya P. Singh

2012-01-01

Full Text Available In the present theoretical investigation, the effect of ferrofluid on the dynamic characteristics of curved slider bearings is presented using Shliomis model which accounts for the rotation of magnetic particles, their magnetic moments, and the volume concentration in the fluid. The modified Reynolds equation for the dynamic state of the bearing is obtained. The results of dynamic stiffness and damping characteristics are presented. It is observed that the effect of rotation of magnetic particles improves the stiffness and damping capacities of the bearings.

Fluid flow dynamics in MAS systems

Science.gov (United States)

Wilhelm, Dirk; Purea, Armin; Engelke, Frank

2015-08-01

The turbine system and the radial bearing of a high performance magic angle spinning (MAS) probe with 1.3 mm-rotor diameter has been analyzed for spinning rates up to 67 kHz. We focused mainly on the fluid flow properties of the MAS system. Therefore, computational fluid dynamics (CFD) simulations and fluid measurements of the turbine and the radial bearings have been performed. CFD simulation and measurement results of the 1.3 mm-MAS rotor system show relatively low efficiency (about 25%) compared to standard turbo machines outside the realm of MAS. However, in particular, MAS turbines are mainly optimized for speed and stability instead of efficiency. We have compared MAS systems for rotor diameter of 1.3-7 mm converted to dimensionless values with classical turbomachinery systems showing that the operation parameters (rotor diameter, inlet mass flow, spinning rate) are in the favorable range. This dimensionless analysis also supports radial turbines for low speed MAS probes and diagonal turbines for high speed MAS probes. Consequently, a change from Pelton type MAS turbines to diagonal turbines might be worth considering for high speed applications. CFD simulations of the radial bearings have been compared with basic theoretical values proposing considerably smaller frictional loss values. The discrepancies might be due to the simple linear flow profile employed for the theoretical model. Frictional losses generated inside the radial bearings result in undesired heat-up of the rotor. The rotor surface temperature distribution computed by CFD simulations show a large temperature gradient over the rotor.

Nonlinear Dynamics Analysis of Tilting Pad Journal Bearing-Rotor System

Directory of Open Access Journals (Sweden)

Jiayang Ying

2011-01-01

Full Text Available The nonlinear dynamics theory is increasingly applied in the dynamics analysis of tilting pad journal bearing-rotor system. However, extensive work on system dynamics done previously neglects the influence caused by the moment of inertia of the pad. In this paper, a comparison is made between the responses of the rotor in the bearings with and without pad inertia effect. Taking the Jeffcott rotor system as an example, the characteristics of bearing-rotor system, such as bifurcation diagram, cycle response, frequency spectrum, phase trajectories, and Poincaré maps, were attained within a certain rotation rate range. The pivotal oil-film force of tilting pad journal bearing was calculated by database method. The results directly demonstrate that considering the influence of the pad moment of inertia, system dynamics characteristics are found more complicated when rotor-bearing system works around natural frequency and system bifurcation is observed forward when rotor-bearing system works on high-speed range.

Embeddability behaviour of tin-based bearing material in dry sliding

International Nuclear Information System (INIS)

Zeren, Adalet

2007-01-01

In this study, tin-based bearing material has been investigated in dry sliding conditions. The low Sb content (7%) is known as SAE 12 and is Sn-Sb-Cu alloy and is widely used in the automotive industry. Wear and friction characteristics were determined with respect to sliding distance, sliding speed and bearing load, using a Tecquipment HFN type 5 journal bearing test equipment. Scanning electron microscopy (SEM) and energy-disperse X-ray spectrography (EDX) are used to understand the tribological events, especially embeddability. Thus, the purpose of this study is to investigate the tribological properties of tin-based bearing alloy used especially in heavy industrial service conditions. Tests were carried out in dry sliding conditions, since despite the presence of lubricant film, under heavy service conditions dry sliding may occur from time to time, causing local wear. As a result of local wear, bearing materials and bearing may be out of their tolerance limits in their early lifetime. Embeddability is an important property due to inversely affecting the hardness and the strength of the bearing

On the validity of the classical hydrodynamic lubrication theory applied to squeeze film dampers

International Nuclear Information System (INIS)

Danaila, S; Moraru, L

2010-01-01

Squeeze film dampers (SFD) are devices utilized to control vibrations of the shafts of high-speed rotating machinery. The SFD - squirrel cage combination is probably the most used system for tuning the stiffness and damping of the supports for rotors installed on ball bearings. Squeeze film dampers are essentially hydrodynamic bearings which contain the ball bearings housings of ball-bearings supported shafts. Consequently, the oil film within the SFD are influenced only by the precession and nutation of the shaft, that is the flow of the oil within the damper is not directly influenced by the spin of the rotor. However, in the classical theory, the flow in the thin film is also governed by the Reynolds equation. In this paper, some of the limits of the classical theory of the SFD are discussed and theoretical and experimental studies, which illustrate the ideas presented herein, are presented as well. The orbits of an unbalanced rotor that is supported by a ball-bearings-SFD-squirrel-cage assembly at one end and by rigidly mounted ball bearings at the other end are computed using the bearing forces provided by the classical short bearing theory. The numerical model also includes the properties of the squirrel cage. The parameters of the squirrel cage were measured, together with the effect of the friction within the assembly. Experimental unbalance responses were also collected for various rotation speeds and unbalances to validate the numerical simulations.

The Effect of Surface Tension on the Gravity-driven Thin Film Flow of Newtonian and Power-law Fluids

Science.gov (United States)

Hu, Bin; Kieweg, Sarah L.

2012-01-01

Gravity-driven thin film flow is of importance in many fields, as well as for the design of polymeric drug delivery vehicles, such as anti-HIV topical microbicides. There have been many prior works on gravity-driven thin films. However, the incorporation of surface tension effect has not been well studied for non-Newtonian fluids. After surface tension effect was incorporated into our 2D (i.e. 1D spreading) power-law model, we found that surface tension effect not only impacted the spreading speed of the microbicide gel, but also had an influence on the shape of the 2D spreading profile. We observed a capillary ridge at the front of the fluid bolus. Previous literature shows that the emergence of a capillary ridge is strongly related to the contact line fingering instability. Fingering instabilities during epithelial coating may change the microbicide gel distribution and therefore impact how well it can protect the epithelium. In this study, we focused on the capillary ridge in 2D flow and performed a series of simulations and showed how the capillary ridge height varies with other parameters, such as surface tension coefficient, inclination angle, initial thickness, and power-law parameters. As shown in our results, we found that capillary ridge height increased with higher surface tension, steeper inclination angle, bigger initial thickness, and more Newtonian fluids. This study provides the initial insights of how to optimize the flow and prevent the appearance of a capillary ridge and fingering instability. PMID:23687391

Numerical study on modeling of liquid film flow under countercurrent flow limitation in volume of fluid method

Energy Technology Data Exchange (ETDEWEB)

Watanabe, Taro, E-mail: watanabe_t@qe.see.eng.osaka-u.ac.jp [Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita-shi, Osaka 565-7895 (Japan); Takata, Takashi, E-mail: takata.takashi@jaea.go.jp [Japan Atomic Energy Agency, 4002 Narita-chou, Oarai-machi, Higashi-Ibaraki-gun, Ibaraki 331-1393 (Japan); Yamaguchi, Akira, E-mail: yamaguchi@n.t.u-tokyo.ac.jp [Graduate School of Engineering, The University of Tokyo, 2-22 Shirakata-Shirane, Tokai-mura, Naka-gun, Ibaraki 319-1188 (Japan)

2017-03-15

Highlights: • Thin liquid film flow under CCFL was modeled and coupled with the VOF method. • The difference of the liquid flow rate in experiments of CCFL was evaluated. • The proposed VOF method can quantitatively predict CCFL with low computational cost. - Abstract: Countercurrent flow limitation (CCFL) in a heat transfer tube at a steam generator (SG) of pressurized water reactor (PWR) is one of the important issues on the core cooling under a loss of coolant accident (LOCA). In order to improve the prediction accuracy of the CCFL characteristics in numerical simulations using the volume of fluid (VOF) method with less computational cost, a thin liquid film flow in a countercurrent flow is modeled independently and is coupled with the VOF method. The CCFL characteristics is evaluated analytically in condition of a maximizing down-flow rate as a function of a void fraction or a liquid film thickness considering a critical thickness. Then, we have carried out numerical simulations of a countercurrent flow in a vertical tube so as to investigate the CCFL characteristics and compare them with the previous experimental results. As a result, it has been concluded that the effect of liquid film entrainment by upward gas flux will cause the difference in the experiments.

Impact of pore-water freshening on clays and the compressibility of hydrate-bearing reservoirs during production

Energy Technology Data Exchange (ETDEWEB)

Jang, Junbong [U.S. Geological Survey, Woods Hole, MA; Cao, Shuang [Louisiana State University, Baton Rouge, LA; Waite, William [U.S. Geological Survey, Woods Hole, MA; Jung, Jongwon [Chungbuk National University, Cheongju-si, Chungbuk, South Korea

2017-06-25

Gas production efficiency from natural hydrate-bearing sediments depends in part on geotechnical properties of fine-grained materials, which are ubiquitous even in sandy hydrate-bearing sediments. The responses of fine-grained material to pore fluid chemistry changes due to freshening during hydrate dissociation could alter critical sediment characteristics during gas production activities. We investigate the electrical sensitivity of fine grains to pore fluid freshening and the implications of freshening on sediment compression and recompression parameters.

Free convection film flows and heat transfer

CERN Document Server

Shang, Deyi

2010-01-01

Presents development of systematic studies for hydrodynamics and heat and mass transfer in laminar free convection, accelerating film boiling and condensation of Newtonian fluids, and accelerating film flow of non-Newtonian power-law fluids. This book provides a system of analysis models with a developed velocity component method.

A wash fluid for drilling into a field

Energy Technology Data Exchange (ETDEWEB)

Belyakov, V M; Badzhurak, R F; Koptelova, Ye K; Rogovoy, V K; Sapozhnikov, N G

1979-01-18

A wash fluid is proposed, used in drilling wells in water and a content of 3-5% by weight starch products. To speed up destruction of the starch products, to the fluid are added amylolytic enzymes in the amount of 0.01-0.1 percent by weight of the starch products' weight. To lower the use of starch products, up to 3% clay can be added to the fluid. The wash fluid is prepared directly at the work site. Dry powder of modified starch is mixed with cold water until a colloidal solution is obtained. Such a wash fluid preserves the required structural-mechanical properties for 3-5 days, which ensures prompt drilling into the waterbearing layer and installation of the filter. Then, during the work process, 5-6 hours before the moment required for lowering the viscosity, to the wash fluid is added the amylolytic enzyme; under its influence, the starch molecules split up, and the viscosity drops sharply. Using this wash fluid enables a reduction in well construction times from the beginning of drilling to the end of development of the water-bearing layer, and a rise in outputs and well service lives by reducing sedimentation of the water-bearing formation and elimination of down times during work required while waiting for destruction of the starch wash fluid under natural conditions.

Supercritical-Carbon Dioxide Fluid Extract from Chrysanthemum indicum Enhances Anti-Tumor Effect and Reduces Toxicity of Bleomycin in Tumor-Bearing Mice

Directory of Open Access Journals (Sweden)

Hong-Mei Yang

2017-02-01

Full Text Available Bleomycin (BLM, a family of anti-tumor drugs, was reported to exhibit severe side effects limiting its usage in clinical treatment. Therefore, finding adjuvants that enhance the anti-tumor effect and reduce the detrimental effect of BLM is a prerequisite. Chrysanthemum indicum, an edible flower, possesses abundant bioactivities; the supercritical-carbon dioxide fluid extract from flowers and buds of C. indicum (CISCFE have strong anti-inflammatory, anti-oxidant, and lung protective effects. However, the role of CISCFE combined with BLM treatment on tumor-bearing mice remains unclear. The present study aimed to investigate the potential synergistic effect and the underlying mechanism of CISCFE combined with BLM in the treatment of hepatoma 22 (H22 tumor-bearing mice. The results suggested that the oral administration of CISCFE combined with BLM could markedly prolong the life span, attenuate the BLM-induced pulmonary fibrosis, suppress the production of pro-inflammatory cytokines (interleukin-6, tumor necrosis factor-α, activities of myeloperoxidase, and malondiadehyde. Moreover, CISCFE combined with BLM promoted the ascites cell apoptosis, the activities of caspases 3 and 8, and up-regulated the protein expression of p53 and down-regulated the transforming growth factor-β1 by activating the gene expression of miR-29b. Taken together, these results indicated that CISCFE could enhance the anti-cancer activity of BLM and reduce the BLM-induced pulmonary injury in H22 tumor-bearing mice, rendering it as a potential adjuvant drug with chemotherapy after further investigation in the future.

Investigation of bearing inner ring-cage thermal characteristics based on CdTe quantum dots fluorescence thermometry

International Nuclear Information System (INIS)

Yan, Ke; Yan, Bei; Li, Ben Q.; Hong, Jun

2017-01-01

Highlights: • A novel method for bearing inner ring/cage thermal monitoring was first presented. • Temperature rise of bearing inner ring in real work condition was obtained. • The rotation speed (6000 r/min) measured here is much higher than all the existing methods. - Abstract: A novel wireless temperature sensor and non-intrusive temperature measurement method for bearing monitoring were proposed in this paper, based on spectrum parameter analysis of CdTe quantum dots films. The CdTe QDs were synthesized and were used in constructing of a sensor film by means of Layer-by-layer Electrostatic Self-assembly method. The fluorescence spectrum properties of the sensor were characterized. At rotation speed 5000–6000 r/min, bearing cage and inner ring temperature were presented first in this paper by the CdTe QDs sensor. The results were verified by theoretical analysis and by thermocouples, with an error typically below 10% or smaller. Compared to the traditional outer ring monitoring, the measurement and monitoring of bearing rolling elements is of very importance, especially at high rotation speed.

Method to Increase Performance of Foil Bearings Through Passive Thermal Management

Science.gov (United States)

Bruckner, Robert

2013-01-01

This invention is a new approach to designing foil bearings to increase their load capacity and improve their reliability through passive thermal management. In the present case, the bearing is designed in such a way as to prevent the carryover of lubricant from the exit of one sector to the inlet of the ensuing sector of the foil bearing. When such passive thermal management techniques are used, bearing load capacity is improved by multiples, and reliability is enhanced when compared to current foil bearings. This concept has recently been tested and validated, and shows that load capacity performance of foil bearings can be improved by a factor of two at relatively low speeds with potentially greater relative improvements at higher speeds. Such improvements in performance with respect to speed are typical of foil bearings. Additionally, operation of these newly conceived bearings shows much more reliability and repeatable performance. This trait can be exploited in machine design to enhance safety, reliability, and overall performance. Finally, lower frictional torque has been demonstrated when operating at lower (non-load capacity) loads, thus providing another improvement above the current state of the art. The objective of the invention is to incorporate features into a foil bearing that both enhance passive thermal management and temperature control, while at the same time improve the hydrodynamic (load capacity) performance of the foil bearing. Foil bearings are unique antifriction devices that can utilize the working fluid of a machine as a lubricant (typically air for turbines and motors, liquids for pumps), and as a coolant to remove excess energy due to frictional heating. The current state of the art of foil bearings utilizes forced cooling of the bearing and shaft, which represents poor efficiency and poor reliability. This invention embodies features that utilize the bearing geometry in such a manner as to both support load and provide an inherent and

A Systems Approach to the Solid Lubrication of Foil Air Bearings for Oil-Free Turbomachinery

Science.gov (United States)

DellaCorte, Christopher; Zaldana, Antonio R.; Radil, Kevin C.

2002-01-01

Foil air bearings are self-acting hydrodynamic bearings which rely upon solid lubricants to reduce friction and minimize wear during sliding which occurs at start-up and shut-down when surface speeds are too low to allow the formation of a hydrodynamic air film. This solid lubrication is typically accomplished by coating the non-moving foil surface with a thin, soft polymeric film. The following paper introduces a systems approach in which the solid lubrication is provided by a combination of self lubricating shaft coatings coupled with various wear resistant and lubricating foil coatings. The use of multiple materials, each providing different functions is modeled after oil-lubricated hydrodynamic sleeve bearing technology which utilizes various coatings and surface treatments in conjunction with oil lubricants to achieve optimum performance. In this study, room temperature load capacity tests are performed on journal foil air bearings operating at 14,000 rpm. Different shaft and foil coating technologies such as plasma sprayed composites, ceramic, polymer and inorganic lubricant coatings are evaluated as foil bearing lubricants. The results indicate that bearing performance is improved through the individual use of the lubricants and treatments tested. Further, combining several solid lubricants together yielded synergistically better results than any material alone.

The Characteristics of Fluid Potential in Mud Diapirs Associated with Gas Hydrates in the Okinawa Trough

Directory of Open Access Journals (Sweden)

Ning Xu

2006-01-01

Full Text Available Many mud diapirs have been identified in the southern Okinawa Trough from a seismic survey using R/V KEXUE I in 2001. The movement and accumulation of free gas related to mud diapirs are discussed in detail by an analysis of fluid potential which is based upon velocity data. It can be found that free gas moves from the higher fluid potential strata to the lower ones and the gas hydrate comes into being during free gas movement meeting the proper criteria of temperature and pressure. In fact, gas hydrates have been found in the upper layers above the mud diapirs and in host rocks exhibiting other geophysical characteristics. As the result of the formation of the gas hydrate, the free gas bearing strata are enclosed by the gas hydrate bearing strata. Due to the high pressure anomalies of the free gas bearing strata the fluid potential increases noticeably. It can then be concluded that the high fluid potential anomaly on the low fluid potential background may be caused by the presence of the free gas below the gas hydrate bearing strata.

Improvement of Thrust Bearing Calculation Considering the Convectional Heating within the Space between the Pads

Directory of Open Access Journals (Sweden)

Monika Chmielowiec-Jablczyk

2018-02-01

Full Text Available A modern thrust bearing tool is used to estimate the behavior of tilting pad thrust bearings not only in the oil film between pad and rotating collar, but also in the space between the pads. The oil flow in the space significantly influences the oil film inlet temperature and the heating of pad and collar. For that reason, it is necessary to define an oil mixing model for the space between the pads. In the bearing tool, the solutions of the Reynolds equation including a cavitation model, the energy equation and the heat transfer equation are done iteratively with the finite volume method by considering a constant flow rate. Both effects—laminar/turbulent flow and centrifugal force—are considered. The calculation results are compared with measurements done for a flooded thrust bearing with nominal eight tilting pads with an outer diameter of 180 mm. The heat convection coefficients for the pad surfaces mainly influence the pad temperature field and are adjusted to the measurement results. In the following paper, the calculation results for variable space distances, influence of different parameters on the bearing behavior and operating condition at high load are presented.

A lattice Boltzmann investigation of steady-state fluid distribution, capillary pressure and relative permeability of a porous medium: Effects of fluid and geometrical properties

Science.gov (United States)

Li, Zi; Galindo-Torres, Sergio; Yan, Guanxi; Scheuermann, Alexander; Li, Ling

2018-06-01

Simulations of simultaneous steady-state two-phase flow in the capillary force-dominated regime were conducted using the state-of-the-art Shan-Chen multi-component lattice Boltzmann model (SCMC-LBM) based on two-dimensional porous media. We focused on analyzing the fluid distribution (i.e., WP fluid-solid, NP fluid-solid and fluid-fluid interfacial areas) as well as the capillary pressure versus saturation curve which was affected by fluid and geometrical properties (i.e., wettability, adhesive strength, pore size distribution and specific surface area). How these properties influenced the relative permeability versus saturation relation through apparent effective permeability and threshold pressure gradient was also explored. The SCMC-LBM simulations showed that, a thin WP fluid film formed around the solid surface due to the adhesive fluid-solid interaction, resulting in discrete WP fluid distributions and reduction of the WP fluid mobility. Also, the adhesive interaction provided another source of capillary pressure in addition to capillary force, which, however, did not affect the mobility of the NP fluid. The film fluid effect could be enhanced by large adhesive strength and fine pores in heterogeneous porous media. In the steady-state infiltration, not only the NP fluid but also the WP fluid were subjected to the capillary resistance. The capillary pressure effect could be alleviated by decreased wettability, large average pore radius and improved fluid connectivity in heterogeneous porous media. The present work based on the SCMC-LBM investigations elucidated the role of film fluid as well as capillary pressure in the two-phase flow system. The findings have implications for ways to improve the macroscopic flow equation based on balance of force for the steady-state infiltration.

Modelling and Identification for Control of Gas Bearings

DEFF Research Database (Denmark)

Theisen, Lukas Roy Svane; Niemann, Hans Henrik; Santos, Ilmar

2015-01-01

Gas bearings are popular for their high speed capabilities, low friction and clean operation, but suffer from poor damping, which poses challenges for safe operation in presence of disturbances. Enhanced damping can be achieved through active lubrication techniques using feedback control laws....... Such control design requires models with low complexity, able to describe the dominant dynamics from actuator input to sensor output over the relevant range of operation. The mathematical models based on first principles are not easy to obtain, and in many cases, they cannot be directly used for control design...... to industrial rotating machinery with gas bearings and to allow for subsequent control design. The paper shows how piezoelectric actuators in a gas bearing are efficiently used to perturb the gas film for identification over relevant ranges of rotational speed and gas injection pressure. Parameter...

Faunal communities at sites of gas- and oil-bearing fluids in Lake Baikal

Science.gov (United States)

Zemskaya, Tamara I.; Sitnikova, Tatiana Y.; Kiyashko, Sergei I.; Kalmychkov, Gennady V.; Pogodaeva, Tatiana V.; Mekhanikova, Irina V.; Naumova, Tatiana V.; Shubenkova, Olga V.; Chernitsina, Svetlana M.; Kotsar, Oleg V.; Chernyaev, Evgeny S.; Khlystov, Oleg M.

2012-12-01

Macro- and meiofaunal communities were examined at four geomorphologically distinct sites with different gas- and oil-bearing fluid characteristics in the northern, central and southern basins of Lake Baikal. All sites had elevated concentrations of bicarbonate, nitrate, sulphate and chloride ions in pore fluids, with highest values at the Frolikha vent. Elevated levels of iron ions were found in pore waters of the St. Petersburg methane seep and the Gorevoy Utes oil seep. The chemical composition of pore waters at the Malenky mud volcano was similar to that reported in earlier work. Consistent with published data, the Frolikha vent (northern basin) and the St. Petersburg methane seep (central basin) were characterised by methane of mixed genesis (thermogenic + biogenic), whereas the methane source was mainly thermogenic at the Gorevoy Utes oil seep (central basin) and biogenic at the Malenky mud volcano (southern basin). In contrast to marine seep ecosystems, the macrofauna was dominated only by amphipods, giant planarians and oligochaetes, whereas bivalves were absent; the meiofauna was similar to its marine counterpart, being dominated by nematodes, cyclops, harpacticoids and ostracods. A statistically significant positive relationship was revealed between faunal abundance and the availability of bacterial mats on seep sediments. Moreover, ANOVA tests showed significant increases in both meiozoobenthic and macrozoobenthic densities at "hot spot" vent/seep sites relative to discharge-free reference sites. The isotopic composition of carbon and nitrogen at various trophic levels of these benthic vent/seep communities was found to differ markedly from that reported by earlier studies for the pelagic and other benthic food webs in Lake Baikal. As in marine seeps, the macrofauna had variable isotopic signatures. Light δ13C and δ15N values suggest the utilization of chemosynthetically fixed and/or methane-derived organic matter. By contrast, the heavy δ13C

An investigation of material properties and tribological performance of magnetron sputtered thin film coatings

Science.gov (United States)

Singh, Harpal

This dissertation is divided into two categories based upon lubrication functionality and its application. The categories are: Dry film lubrication and Fluid film lubrication with thin film coatings. Thin film coatings examined in this work were deposited using closed field unbalanced magnetron sputtering and RF-DC coupled magnetron sputtering systems. In Dry/Solid film lubrication, the mechanical, structural and tribological properties of two Molybdenum disulphide (MoS2) based coatings are examined and evaluated. Among the two coatings, one coating is doped with Ti (Ti-MoS2) and the other is a combination of metal, lubricant and oxide (Sb2O3/Au - MoS2). These coatings are known to provide low friction in vacuum environments. The goal of this work was to evaluate friction and wear performance of MoS2 doped coatings in unidirectional and reciprocating sliding contact under different environmental conditions. Sliding contact results showed friction and wear dependence on temperature and humidity. The formation and removal of transfer films and the recrystallization and reorientation of basal layers on the steel counterface was observed as the mechanism for low friction. Structural analysis revealed a relationship between the microstructural properties and tribological performance. It was also observed that the addition of dopants (Ti, Au, Sb 2O3) improved the mechanical properties as compared to pure MoS2 coatings. Further, the rolling contact performance of the coatings was measured on a five ball on rod tribometer and a Thrust bearing tribometer under vacuum and air environments. The rolling contact experiments indicated that life of the rolling components depend on the amount of material present between the contacts. Fluid film lubrication with thin film coatings investigates the possibilities to improve the performance and durability of tribological components when oils and thin films are synergistically coupled. In this work, the ability of a Diamond Like Carbon

Fluid-injection and the mechanics of frictional stability of shale-bearing faults

Science.gov (United States)

Scuderi, Marco Maria; Collettini, Cristiano; Marone, Chris

2017-04-01

Fluid overpressure is one of the primary mechanisms for triggering tectonic fault slip and human-induced seismicity. This mechanism is appealing because fluids lubricate the fault and reduce the effective normal stress that holds the fault in place. However, current models of earthquake nucleation, based on rate- and state- friction, imply that stable sliding is favored by the increase of pore fluid pressure. Despite this apparent dilemma, there are a few studies on the role of fluid pressure in frictional stability under controlled, laboratory conditions. Here, we describe laboratory experiments on shale fault gouge, conducted in the double direct shear configuration in a true-triaxial machine. To characterize frictional stability and hydrological properties we performed three types of experiments: 1) stable sliding shear experiment to determine the material failure envelope resulting in fault strength of µ=0.28 and fault zone permeability (k 10-19m2); 2) velocity step experiments to determine the rate- and state- frictional properties, characterized by a velocity strengthening behavior with a negative rate parameter b, indicative of stable aseismic creep; 3) creep experiment to study fault slip evolution with increasing pore-fluid pressure. In these creep experiments fault slip history can be divided in three main stages: a) for low fluid pressure the fault is locked and undergoes compaction; b) with increasing fluid pressurization, we observe aseismic creep (i.e. v=0.0001 µm/s) associated with fault dilation, with maintained low permeability; c) As fluid pressure is further increased and we approach the failure criteria fault begins to accelerate, the dilation rate increases causing an increase in permeability. Following the first acceleration we document complex fault slip behavior characterized by periodic accelerations and decelerations with slip velocity that remains slow (i.e. v 200 µm/s), never approaching dynamic slip rates. Surprisingly, this complex

Unsteady thin film flow of a fourth grade fluid over a vertical moving and oscillating belt

Directory of Open Access Journals (Sweden)

Taza Gul

2016-09-01

Full Text Available This article studies the unsteady thin film flow of a fourth grade fluid over a moving and oscillating vertical belt. The problem is modeled in terms of non-nonlinear partial differential equations with some physical conditions. Both problems of lift and drainage are studied. Two different techniques namely the adomian decomposition method (ADM and the optimal homotopy asymptotic method (OHAM are used for finding the analytical solutions. These solutions are compared and found in excellent agreement. For the physical analysis of the problem, graphical results are provided and discussed for various embedded flow parameters.

Free-Standing, Flexible, Superomniphobic Films.

Science.gov (United States)

Vahabi, Hamed; Wang, Wei; Movafaghi, Sanli; Kota, Arun K

2016-08-31

Fabrication of most superomniphobic surfaces requires complex process conditions or specialized and expensive equipment or skilled personnel. In order to circumvent these issues and make them end-user-friendly, we developed the free-standing, flexible, superomniphobic films. These films can be stored and delivered to the end-users, who can readily attach them to virtually any surface (even irregular shapes) and impart superomniphobicity. The hierarchical structure, the re-entrant texture, and the low solid surface energy render our films superomniphobic for a wide variety of liquids. We demonstrate that our free-standing, flexible, superomniphobic films have applications in enhanced chemical resistance and enhanced weight bearing.

Tribological behaviour of conventional Al–Sn and equivalent Al–Pb ...

Indian Academy of Sciences (India)

Unknown

Al–Sn alloys have a very long history (Forrester 1960) to be used as bearing ... has a low modulus of elasticity and apart from indium, lead has the lowest .... film (figures 5a,b), which consists of a thin fluid film and a mixed film of oil-lead ...

Enhancing damping of gas bearings using linear parameter-varying control

DEFF Research Database (Denmark)

Theisen, Lukas Roy Svane; Niemann, Hans Henrik; Galeazzi, Roberto

2017-01-01

systems to regulate the injection pressure of the fluid. Due to the strong dependencies of system performance on system parameters, the sought controller should be robust over a large range of operational conditions. This paper addresses the damping enhancement of controllable gas bearings through robust...... control approaches. Through an extensive experimental campaign the paper evaluates two robust controllers, a linear parametervarying (LPV) controller and ∞ controller, on their capability to guarantee stability and performance of a gas bearing across the large operational envelopes in rotational speed...

The Research Status and Progress of Heavy/Large Hydrostatic Thrust Bearing

Directory of Open Access Journals (Sweden)

Xibing Li

2014-03-01

Full Text Available How to improve the rotation speed of heavy/large CNC vertical lathe, the machining efficiency, and machining precision is one of the key issues which need to be solved urgently. Hydrostatic thrust bearing is the key part to the heavy/large CNC vertical lathe; its performance directly affects the machining quality and operation efficiency. This paper analyses the latest research results from the perspective of the mechanical properties of hydrostatic thrust bearing, oil film lubrication, static pressure bearing thermal deformation, and the high efficiency refrigeration and evaluates the future scientific research direction in this area. Analysis shows that with the development of hydrostatic thrust bearing to the high speed, high precision, high efficiency, high stability, high multifunction, and high power, the study of hydrostatic thrust bearing will focus on the optimal design of the oil chamber to produce the least amount of heat, how to control the thermal deformation of hydrostatic thrust bearing, and the high efficiency refrigeration to ensure the machining accuracy of CNC equipment.

Structure and corrosion properties of Cr coating deposited on aerospace bearing steel

Science.gov (United States)

Wang, Fangfang; Zhang, Fengxiang; Zheng, Lijing; Zhang, Hu

2017-11-01

The corrosion protection of chromium coating deposited on aerospace bearing steels by using the Filtered Cathodic Vacuum Arc deposition- Metal Evaporation Vacuum Arc duplex technique (MEVVA-FCVA) had been investigated. The protection efficiency of chromium coating on different substrate materials had also been evaluated. The chromium coating was mainly composed of nanocrystallineα-Cr in a range of 50-200 nm. The orientation distributions of α-Cr film on substrates with different composition had a certain difference to each other. Electrochemical experimental results indicated that the chromium coating significantly improved the corrosion resistance of experimental bearing steels in 3.5% NaCl solution. The protective efficiency of chromium films were all over 98%. The corrosion resistance of chromium coating was influenced by the chemical composition of substrate material. The chromium coatings on higher Cr-containing substrate displayed lower corrosion current density and more positive corrosion potential. The increase of passive film thickness and the formation of a mass of chromium oxide and hydroxide on the surface are responsible for the improved corrosion properties.

Solar advanced internal film receiver

International Nuclear Information System (INIS)

Torre Cabezas, M. de la

1990-01-01

In a Solar Central Internal Film Receiver, the heat absorbing fluid (a molten nitrate salt) flows in a thin film down over the non illuminated side of an absorber panel. Since the molten salt working fluid is not contained in complicated tube manifolds, the receiver design is simples than a conventional tube type-receiver resulting in a lower cost and a more reliable receiver. The Internal Film Receiver can be considered as an alternative to the Direct Absorption Receiver, in the event that the current problems of the last one can not be solved. It also describes here the test facility which will be used for its solar test, and the test plans foreseen. (Author) 17 refs

Bifurcation and nonlinear dynamic analysis of a flexible rotor supported by relative short gas journal bearings

International Nuclear Information System (INIS)

Wang, C.-C.; Jang, M.-J.; Yeh, Y.-L.

2007-01-01

This paper studies the bifurcation and nonlinear behaviors of a flexible rotor supported by relative short gas film bearings. A time-dependent mathematical model for gas journal bearings is presented. The finite difference method with successive over relation method is employed to solve the Reynolds' equation. The system state trajectory, Poincare maps, power spectra, and bifurcation diagrams are used to analyze the dynamic behavior of the rotor and journal center in the horizontal and vertical directions under different operating conditions. The analysis reveals a complex dynamic behavior comprising periodic and subharmonic response of the rotor and journal center. This paper shows how the dynamic behavior of this type of system varies with changes in rotor mass and rotational velocity. The results of this study contribute to a further understanding of the nonlinear dynamics of gas film rotor-bearing systems

Comparison of in vivo polyethylene wear particles between mobile- and fixed-bearing TKA in the same patients.

Science.gov (United States)

Minoda, Yukihide; Hata, Kanako; Ikebuchi, Mitsuhiko; Mizokawa, Shigekazu; Ohta, Yoichi; Nakamura, Hiroaki

2017-09-01

Polyethylene wear particle generation is one of the most important factors that affects the mid- to long-term results of total knee arthroplasties (TKA). Mobile-bearing total knee prostheses were developed to reduce polyethylene wear generation. However, whether mobile-bearing prostheses actually generate fewer polyethylene wear particles than fixed-bearing prostheses remains controversial. The aim of this study was to compare, within individual patients, the in vivo polyethylene wear particles created by a newly introduced mobile-bearing prosthesis in one knee and a conventional fixed-bearing prosthesis in other knee. Eighteen patients receiving bilateral TKAs to treat osteoarthritis were included. The synovial fluid was obtained from 36 knees at an average of 3.5 years after the operation. The in vivo polyethylene wear particles were isolated from the synovial fluid using a previously validated method and examined using a scanning electron microscope and an image analyser. The size and shape of the polyethylene wear particles from the mobile-bearing prostheses were similar to those from the conventional fixed-bearing prostheses. Although the number of wear particles from the mobile-bearing prosthesis (1.63 × 10 7  counts/knee) appeared smaller than that from the fixed-bearing prosthesis (2.16 × 10 7  counts/knee), the difference was not statistically significant. The current in vivo study shows that no statistically significant differences were found between the polyethylene wear particles generated by a newly introduced mobile-bearing PS prosthesis and a conventional fixed-bearing PS prosthesis during the early clinical stage after implantation. Therapeutic study, Level III.

Tilting-Pad Journal Bearings with Active Lubrication Applied as Calibrated Shakers: Theory and Experiment

DEFF Research Database (Denmark)

Cerda Varela, Alejandro Javier; Santos, Ilmar

2014-01-01

In recent years, a continuous research effort has transformed the conventional tilting-pad journal bearing into a mechatronic machine element. The addition of electromechanical elements provides the possibility of generating controllable forces over the rotor as a function of a suitable control...... directly into the bearing clearance. The injected flow is controlled by means of a servovalve. The theoretical model includes the dynamics of servovalves and pipelines using a lumped parameter approach, whereas the coupling between the hydraulic system and the bearing oil film is modeled using a modified...

Effect of Magnetohydrodynamic Couple Stresses on Dynamic Characteristics of Exponential Slider Bearing

Directory of Open Access Journals (Sweden)

N.B. Naduvinamani

2017-05-01

Full Text Available The effect of couple stresses on static and dynamic characteristics of exponential slider bearing in the presence of magnetic field considering squeeze action is theoretically analyzed in this paper. The modified magnetohydrodynamic couple stress Reynolds type equation is derived on the basis of Stokes couple stress model and closed form expressions are obtained for static and dynamic character coefficients. Comparing with bearing lubricated with non-conducting Newtonian lubricants, the magnetohydrodynamic couple stress lubrication provides the higher steady load carrying capacity, dynamic stiffness and damping coefficient. The exponential bearing shows higher efficiency for small film thickness at higher value of couple stress parameter and Hartmann number.

Fluid diversion in oil recovery

International Nuclear Information System (INIS)

Nimir, Hassan B.

1999-01-01

In any oil recovery process, large scale heterogeneities, such as fractures, channels, or high-permeability streaks, can cause early break through of injected fluid which will reduce oil recovery efficiency. In waterflooding, enhanced oil recovery, and acidizing operations, this problem is particularly acute because of the cost of the injected fluid. On the other hand coping with excess water production is always a challenging task for field operators. The cost of handling and disposing produced water can significantly shorten the economic production life of an oil well. The hydrostatic pressure created by high fluid levels in a well (water coning) is also detrimental to oil production. In this paper, the concept of fluid diversion is explained. Different methods that are suggested to divert the fluid into the oil-bearing-zones are briefly discussed, to show their advantages and disadvantages. Methods of reducing water production in production well are also discussed. (Author)

Polymer Drilling Fluid with Micron-Grade Cenosphere for Deep Coal Seam

Directory of Open Access Journals (Sweden)

Peng Xu

2015-01-01

Full Text Available Traditional shallow coal seam uses clean water, solid-free system, and foam system as drilling fluid, while they are not suitable for deep coal seam drilling due to mismatching density, insufficient bearing capacity, and poor reservoir protection effect. According to the existing problems of drilling fluid, micron-grade cenosphere with high bearing capacity and ultralow true density is selected as density regulator; it, together with polymer “XC + CMC” and some other auxiliary agents, is jointly used to build micron-grade polymer drilling fluid with cenosphere which is suitable for deep coal seam. Basic performance test shows that the drilling fluid has good rheological property, low filtration loss, good density adjustability, shear thinning, and thixotropy; besides, drilling fluid flow is in line with the power law rheological model. Compared with traditional drilling fluid, dispersion stability basically does not change within 26 h; settlement stability evaluated with two methods only shows a small amount of change; permeability recovery rate evaluated with Qinshui Basin deep coal seam core exceeds 80%. Polymer drilling fluid with cenosphere provides a new thought to solve the problem of drilling fluid density and pressure for deep coal seam drilling and also effectively improves the performance of reservoir protection ability.

Fabrication of nanochannels on polyimide films using dynamic plowing lithography

Science.gov (United States)

Stoica, Iuliana; Barzic, Andreea Irina; Hulubei, Camelia

2017-12-01

Three distinct polyimide films were analyzed from the point of view of their morphology in order to determine if their surface features can be adapted for applications where surface anisotropy is mandatory. Channels of nanometric dimensions were created on surface of the specimens by using a less common atomic force microscopy (AFM) method, namely Dynamic Plowing Lithography (DPL). The changes generated by DPL procedure were monitored through the surface texture and other functional parameters, denoting the surface orientation degree and also bearing and fluid retention properties. The results revealed that in the same nanolithography conditions, the diamine and dianhydride moieties have affected the characteristics of the nanochannels. This was explained based on the aliphatic/aromatic nature of the monomers and the backbone flexibility. The reported data are of great importance in designing custom nanostructures with enhanced anisotropy on surface of polyimide films for liquid crystal orientation or guided cell growth purposes. At the end, to track the effect of the nanolithography process on the tip sharpness, degradation and contamination, the blind tip reconstruction was performed on AFM probe, before and after lithography experiments, using TGT1 test grating AFM image.

Heat transfer for falling film evaporation of industrially relevant fluids up to very high Prandtl numbers

Science.gov (United States)

Gourdon, Mathias; Karlsson, Erik; Innings, Fredrik; Jongsma, Alfred; Vamling, Lennart

2016-02-01

In many industrial applications, falling film evaporation is an attractive technique for solvent removal due to high heat transfer and low residence times. Examples are the powder production in the dairy industry and in kraft pulp production process to remove water from so called black liquor. Common for both applications is that the fluids exhibit high viscosities in industrial practice. In this paper, results from experimental studies on both black liquor and a dairy product are reported for Prandtl numbers up to 800. The results are compared with several existing correlation in literature, and the need for a modified correlation is recognized especially to cover higher Prandtl-numbers. The following correlation for the turbulent flow region with 3 < Pr < 800 was derived from the data: {Nu}t = 0.0085 \\cdot Re^{0.2} \\cdot {Pr^{0.65}} The correlation has been compared to literature data from one additional study on two other fluids (propylene glycol and cyclohexanol) with fairly high Prandtl-numbers, from 40 to 58 and from 45 to 155 respectively and the agreement was within ±40 %.

Several particular aspects of hydrostatic shaft guide bearings in mechanical liquid sodium pumps

International Nuclear Information System (INIS)

Elie, X.

A number of problems arise with immersed hydrostatic shaft guide bearings in sodium pumps, mainly at high-temperature operation. Experience has shown that a substantial bearing clearance is required which, in present designs, takes a considerable amount of fluid from the pumps. A new design is suggested, resulting in a very appreciable reduction in the additional flow requirement, while maintaining a comparable load capacity by a hydrodynamic effect

Analysis of the gas-lubricated flat-sector-pad thrust bearing

Science.gov (United States)

Etsion, I.

1976-01-01

A flat sector-shaped pad geometry for a gas-lubricated thrust bearing is analyzed considering both the pitch and roll of the pad. It is shown that maximum load capacity is achieved when the pad is tilted so as to create uniform minimum film thickness along the pad trailing edge. Performance characteristics for various geometries and operating conditions of gas thrust bearings are presented in the form of design curves, and a comparison is made with the rectangular slider approximation. It is found that this approximation is unsafe for practical design, since it always overestimates load capacity.

Numerical research on rotating speed influence and flow state distribution of water-lubricated thrust bearing

International Nuclear Information System (INIS)

Deng Xiao; Deng Liping; Huang Wei

2015-01-01

Water-lubricated thrust bearing is one of the key parts in canned motor pump, for example, the RCP in AP1000, and it functions to balance axial loads. A calculation model which can handle all flow state lubrication performance for water-lubricated thrust bearing has been presented. The model first includes laminar and turbulent Reynolds' equation. Then to get continuous viscosity coefficients cross critical Reynolds number, a transition zone which ranges based on engineering experience is put up, through which Hermite interpolation is employed. The model is numerically solved in finite difference method with uniform grids. To accelerate the calculation process, multigrid method and line relaxation is adopted within the iteration procedure. A medium sized water-lubricated tilting pad thrust bearing is exampled to verify the calculation model. Results suggest that as rotating speed enlarges, lubrication state distribution of the thrust bearing gradually tends to turbulent lubrication from the intersection corner of pad outer diameter and pad inlet to the opposite, minimum water film thickness increases approximately linearly, maximum water film pressure has little change, meanwhile the friction power grows nearly in exponential law which could result in bad effect by yielding much more heat. (author)

Modelling Hermetic Compressors Using Different Constraint Equations to Accommodate Multibody Dynamics and Hydrodynamic Lubrication

DEFF Research Database (Denmark)

Estupinan, Edgar Alberto; Santos, Ilmar

2009-01-01

elements are supported by fluid film bearings, where the hydrodynamic interaction forces are described by the Reynolds equation. The system of nonlinear equations is numerically solved for three different restrictive conditions of the motion of the crank, where the third case takes into account lateral...... and tilting oscillations of the extremity of the crankshaft. The numerical results of the behaviour of the journal bearings for each case are presented giving some insights into design parameters such as, maximum oil film pressure, minimum oil film thickness, maximum vibration levels and dynamic reaction...

Meniscal Tear Film Fluid Dynamics Near Marx’s Line

KAUST Repository

Zubkov, V. S.; Breward, C. J. W.; Gaffney, E. A.

2013-01-01

meniscus. However, resolving tear film behaviour within the meniscus and especially its apices is required to characterise the flow dynamics where the tear film is especially thin, and thus most susceptible to evaporatively induced hyperosmolarity

Dynamics Modeling and Analysis of Local Fault of Rolling Element Bearing

Directory of Open Access Journals (Sweden)

Lingli Cui

2015-01-01

Full Text Available This paper presents a nonlinear vibration model of rolling element bearings with 5 degrees of freedom based on Hertz contact theory and relevant bearing knowledge of kinematics and dynamics. The slipping of ball, oil film stiffness, and the nonlinear time-varying stiffness of the bearing are taken into consideration in the model proposed here. The single-point local fault model of rolling element bearing is introduced into the nonlinear model with 5 degrees of freedom according to the loss of the contact deformation of ball when it rolls into and out of the local fault location. The functions of spall depth corresponding to defects of different shapes are discussed separately in this paper. Then the ode solver in Matlab is adopted to perform a numerical solution on the nonlinear vibration model to simulate the vibration response of the rolling elements bearings with local fault. The simulation signals analysis results show a similar behavior and pattern to that observed in the processed experimental signals of rolling element bearings in both time domain and frequency domain which validated the nonlinear vibration model proposed here to generate typical rolling element bearings local fault signals for possible and effective fault diagnostic algorithms research.

Coupling Fluid and Solute Dynamics Within the Ocular Surface Tear Film: A Modelling Study of Black Line Osmolarity

KAUST Repository

Zubkov, V. S.

2012-07-06

We present a mathematical model describing the spatial distribution of tear film osmolarity across the ocular surface of a human eye during one blink cycle, incorporating detailed fluid and solute dynamics. Based on the lubrication approximation, our model comprises three coupled equations tracking the depth of the aqueous layer of the tear film, the concentration of the polar lipid, and the concentration of physiological salts contained in the aqueous layer. Diffusive boundary layers in the salt concentration occur at the thinnest regions of the tear film, the black lines. Thus, despite large Peclet numbers, diffusion ameliorates osmolarity around the black lines, but nonetheless is insufficient to eliminate the build-up of solute in these regions. More generally, a heterogeneous distribution of solute concentration is predicted across the ocular surface, indicating that measurements of lower meniscus osmolarity are not globally representative, especially in the presence of dry eye. Vertical saccadic eyelid motion can reduce osmolarity at the lower black line, raising the prospect that select eyeball motions more generally can assist in alleviating tear film hyperosmolarity. Finally, our results indicate that measured evaporative rates will induce excessive hyperosmolarity at the black lines, even for the healthy eye. This suggests that further evaporative retardation at the black lines, for instance due to the cellular glycocalyx at the ocular surface or increasing concentrations of mucus, will be important for controlling hyperosmolarity as the black line thins. © 2012 Society for Mathematical Biology.

Field dependent shape variation of magnetic fluid droplets on magnetic dots

International Nuclear Information System (INIS)

Lee, Chiun-Peng; Yang, Shu-Ting; Wei, Zung-Hang

2012-01-01

The morphology of magnetic fluid droplets on magnetic thin film dots is studied experimentally, including the aspect ratio and the contact angle variation of the droplets. Under a uniform external magnetic field, the droplet's aspect ratio increases with the external field and with the diameter of the magnetic dot due to the concentrated magnetic flux inside the magnetic fluid droplet. Similar to the electrical wetting phenomenon, the induced magnetic dipoles in the magnetic film and in the magnetic fluid near the solid–liquid interface change the solid–liquid interfacial tension, and in consequence reduce the apparent contact angle of the magnetic fluid droplet. - Highlights: ► Morphology of ferrofluid droplets on magnetic thin film dots was studied experimentally. ► Aspect ratio of ferrofluid droplets was found to increase with increasing of magnetic field. ► Liquid–solid contact angle of ferrofluid droplets was found to vary with magnetic field. ► Relationship between magnetic field and the liquid–solid interfacial tension was modeled.

Rb-Sr, K-Ar, and stable isotope evidence for the ages and sources of fluid components of gold-bearing quartz veins in the northern Sierra Nevada foothills metamorphic belt, California

Science.gov (United States)

Böhlke, John Karl; Kistler, R. W.

1986-01-01

Gold-bearing quartz veins occur in and near major fault zones in deformed oceanic and island-arc rocks west of the main outcrop of the Sierra Nevada composite batholith. Veins typically occupy minor reverse faults that crosscut blueschist to amphibolite-grade metamorphic rocks whose metamorphic ages range from early Paleozoic to Jurassic. Vein micas and carbonate-quartz-mica assemblages that formed by hydrothermal metasomatism of ultramafic wall rocks in the Alleghany, Grass Valley, Washington, and Mother Lode districts yield concordant K-Ar and Rb-Sr ages. The dated veins are significantly younger than prograde metamorphism, penetrative deformation, and accretion of their host rocks to the continental margin. New and previously published mineralization ages from 13 localities in the Sierra foothills range from about 140 to 110 m.y. ago, with mean and median between 120 and 115 m.y. The age relations suggest that mineralizing fluids were set in motion by deep magmatic activity related to the resumption of east-dipping subduction along the western margin of North America following the Late Jurassic Nevadan collision event.CO 2 -bearing fluids responsible for metasomatism and much of the vein mica, carbonate, albite, and quartz deposition in several northern mines were isotopically heavy (delta 18 O [asymp] 8-14ppm; delta D between about -10 and -50ppm) and do not resemble seawater, magmatic, or meteoric waters. Metasomatic and vein-filling mica, dolomite, magnesite, and quartz in altered ultramafic rocks generally formed from fluids with similar Sr and O isotope ratios at a given locality. Consistent quartz-mica delta 18 O fractionations (delta 18 O (sub Q-M) = 4.5-4.9ppm) from various localities imply uniform equilibration temperatures, probably between 300 degrees and 350 degrees C. On a local (mine) scale, fluids responsible for both carbonate alteration of mafic and ultramafic wall rocks and albitic alteration of felsic and pelitic rocks had similar Sr isotope

The Chevron Foil Thrust Bearing: Improved Performance Through Passive Thermal Management and Effective Lubricant Mixing

Science.gov (United States)

Bruckner, Robert

2013-01-01

An improved foil thrust bearing is described that eliminates or reduces the need for forced cooling of the bearing foils while at the same time improves the load capacity of the bearing, enhances damping, provides overload tolerance, and eliminates the high speed load capacity drop-off that plagues the current state of the art. The performance improvement demonstrated by the chevron foil thrust bearing stems from a novel trailing edge shape that splays the hot lubricant in the thin film radially, thus preventing hot lubricant carry-over into the ensuing bearing sector. Additionally, the chevron shaped trailing edge induces vortical mixing of the hot lubricant with the gas that is naturally resident within the inter-pad region of a foil thrust bearing. The elimination of hot gas carry-over in combination with the enhanced mixing has enabled a completely passive thermally managed foil bearing design. Laboratory testing at NASA has confirmed the original analysis and reduced this concept to practice.

Development, implementation and assessment of specific closure laws for inverted-annular film-boiling in a two-fluid model

International Nuclear Information System (INIS)

Cachard, F. de

1994-10-01

Inverted-annular film-boiling (IAFB) is one of the post-burnout heat transfer modes taking place, in particular, during the reflooding phase of the loss-of-coolant accident, when the liquid at the quench front is subcooled. Under IAFB conditions, a continuous liquid core is separated from the wall by a superheated vapour film. The heat transfer rate in IAFB is influenced by the flooding rate, liquid subcooling, pressure, and the wall geometry and temperature. These influences can be accounted by a two-fluid model with physically sound closure laws for mass, momentum and heat transfer between the wall, the vapour film, the vapour-liquid interface, and the liquid core. The applicability of existing IAFB two-fluid models is limited. This is attributed to shortcomings in the description of heat transfer within the liquid core, to use of certain correlations outside their validity range, and to a limited use of experimental information on IAFB. The usual approach has been to develop models employing generally applicable closure laws including, however, adjustable parameters, and to adjust these using global experimental results. The present approach has been to develop IAFB-specific closure laws in such a form that they could be adjusted separately using detailed, IAFB-relevant, experimental result. Steady-state results, including heat flux, wall temperature and void fraction data have been used for the adjustment. A key issue in IAFB modeling is to predict how the heat flux reaching the vapour-liquid interface is split into a liquid heating term and a vaporization term. In the model proposed, convective liquid heating is related to the liquid velocity relative to the interface, and not to the absolute liquid velocity, as in previous models. This relative velocity is deduced from the interfacial shear stress, using the liquid-interface friction law. With this modification, the prediction of the experimental trends is greatly improved. (author) figs., tabs., refs

Combined Effect of Piezoviscous Dependency and Non-Newtonian Couple Stress on Squeeze-Film Porous Annular Plate

Science.gov (United States)

Vasanth, K. R.; Hanumagowda, B. N.; Santhosh Kumar, J.

2018-04-01

Squeeze film investigations focus upon film pressure, load bearing quantity and the minimum thickness of film. The combined effect of pressure viscous dependent and non- Newtonian couple stress in porous annular plate is studied. The modified equations of one dimensional pressure, load bearing quantity, non dimensional squeeze time are obtained. The conclusions obtained in the study are found to be in very good agreement compared to the previous results which are published. The load carrying capacity is increased due to the variation in the pressure dependent viscosity and also due to the couple stress effect. Finally this results in change in the squeeze film timings.

Diagnostic evaluation of rolling behavior in ball bearings by ultrasonic technique

International Nuclear Information System (INIS)

Wakabayashi, T

2012-01-01

Failures of machines having rotating parts are mostly caused by damage to bearings and there exist increasing demands for detecting damaged bearings at an early stage. However, conventional diagnostic methods, such as measuring temperature and observing vibration, have found difficulties in performing the early detection, so that more advanced diagnosis is necessary. This study therefore applies an ultrasonic technique as an advanced diagnostic method to bearing life tests. Ultrasonic wave pulses (UWP) emitted from a piezoelectric UWP generator can partially reflect from the interfaces of contact zones within the housing and the bearing with regard to the different acoustic impedance between a solid-to-solid contact and a contact dominated by some fluid layers. Hence, the intensity of the resultant UWP echoes can be determined by the real contact area formed at the interfaces. The experimental results of UWP echoes under the different operating conditions have demonstrated that the time intervals between peaks of UWP echoes varied in accordance with the movement of rolling balls and the lubricating phenomena in bearings. This behavior has further suggested the possibility of the early detection of abnormalities in ball bearings by using the variation in UWP echoes.

Preparation and characterization of layer-by-layer self-assembled polyelectrolyte multilayer films doped with surface-capped SiO2 nanoparticles.

Science.gov (United States)

Yang, Guangbin; Ma, Hongxia; Yu, Laigui; Zhang, Pingyu

2009-05-15

SiO(2) nanoparticles capped with gamma-aminopropyltrimethoxysilane were doped into polyelectrolyte (poly(allylamine hydrochloride), PAH, and poly(acrylic acid), PAA) multilayer films via spin-assisted layer-by-layer self-assembly. The resulting as-prepared multilayer films were heated at a proper temperature to generate cross-linked composite films with increased adhesion to substrates. The tribological behavior of the multilayer films was evaluated on a microtribometer. It was found that SiO(2)-doped composite films had better wear resistance than pure polyelectrolyte multilayers, possibly because doped SiO(2) nanoparticles were capable of enhancing load-carrying capacity and had "miniature ball bearings" effect. Moreover, heat-treatment had significant effect on the morphology of the composite films. Namely, heat-treated (SiO(2)/PAA)(9) film had a larger roughness than the as-prepared one, due to heat-treatment-induced agglomeration of SiO(2) nanoparticles and initiation of defects. However, heat-treated (PAH/PAA)(3)/(SiO(2)/PAA)(3)(PAH/PAA)(3) film had greatly reduced roughness than the as-prepared one, and it showed considerably improved wear resistance as well. This could be closely related to the "sandwich-like" structure of the composite multilayer film. Namely, the outermost strata of composite multilayer film were able to eliminate defects associated with the middle strata, allowing nanoparticles therein to maintain strength and robustness while keeping soft and fluid-like exposed surface. And the inner strata were well anchored to substrate and acted as an initial "bed" for SiO(2) nanoparticles to be inhabited, resulting in good antiwear ability.

Improved adaptability of polyaryl-ether-ether-ketone with texture pattern and graphite-like carbon film for bio-tribological applications

Science.gov (United States)

Ren, Siming; Huang, Jinxia; Cui, Mingjun; Pu, Jibin; Wang, Liping

2017-04-01

With the development of surface treatment technology, an increasing number of bearings, seals, dynamic friction drive or even biomedical devices involve a textured surface to improve lubrication and anti-wear. The present investigation has been conducted in order to evaluate the friction and wear behaviours of textured polyaryl-ether-ether-ketone (PEEK) coated with a graphite-like carbon (GLC) film sliding against stainless steel pin in biological medium. Compared with pure PEEK, the PEEK coated with GLC film shows excellent tribological performance with a low friction of 0.08 and long lifetime (wear volumes are about 3.78 × 10-4 mm3 for un-textured one and 2.60 × 10-4 mm3 for textured GLC film after 36,000 s of sliding) under physiological saline solution. In particular, the GLC film with appropriate dimple area density is effective to improve friction reduction and wear resistance properties of PEEK substrate under biological solution, which is attributed to the entrapment of wear debris in the dimples to inhibit the graphitization and the fluid dynamic pressure effect derived from the texture surface to increase the thickness in elastohydrodynamic lubrication (EHL) film during sliding motions. Moreover, the friction coefficient of GLC film under physiological saline solution decreases with the increase in the applied load. With the increasing applied load, the texture surface is responsible for accounting the improved wear resistance and a much lower graphitization of the GLC film during whole test.

Simulations geometric structures of the stepped profile bearing surface of the piston

Directory of Open Access Journals (Sweden)

Wroblewski Emil

2017-01-01

Full Text Available The main node piston-pin-piston rings are most responsible for the formation of mechanical losses. It is advisable to reduce friction losses in the piston-cylinder group lead to an increase in the overall efficiency of the engine and thus reduce the fuel consumption. The method to reduce the area covered by the oil film is a modification of the bearing surface of the piston by adjusting the profile. In this paper the results of simulation for the stepped microgeometry piston bearing surface are presented.

An algorithm for nonlinear thermal analysis of fuel bearing pads

International Nuclear Information System (INIS)

Attia, M.H.; D'Silva, N.

1983-01-01

An algorithm has been developed for accurate prediction of the temperature field in a CANDU fuel bearing pad and the extent of the nucleate boiling in the crevice region. The methodology recognizes the nonlinear nature of the problem due to the fact that local boiling is both controlling and being controlled by the conditions of heat transfer at the boundaries. The finite difference model accounts for the volumetric effect of the thermal contact resistance at the bearing pad/pressure tube interface. It also allows the evaluation of the thermal barrier effect caused by applying an oxide film on the radiused surface of the bearing pad. Information pertaining to the distribution of the coefficient of heat transfer over water-cooled surfaces has been generated. Analysis of the results indicated the significance of considering the nonlinear behaviour of the system in determining its state of equilibrium. It also indicated that, depending on the thickness of the oxide layer and the position of the bearing pad along the core of the reactor, the nucleate boiling process can be prevented

The spectral analysis of an aero-engine assembly incorporating a squeeze-film damper

Science.gov (United States)

Holmes, R.; Dede, M. M.

1989-01-01

Aero-engine structures have very low inherent damping and so artificial damping is often introduced by pumping oil into annular gaps between the casings and the outer races of some or all of the rolling-element bearings supporting the rotors. The thin oil films so formed are called squeeze film dampers and they can be beneficial in reducing rotor vibration due to unbalance and keeping to reasonable limits the forces transmitted to the engine casing. However, squeeze-film dampers are notoriously non-linear and as a result can introduce into the assembly such phenomena as subharmonic oscillations, jumps and combination frequencies. The purpose of the research is to investigate such phenomena both theoretically and experimentally on a test facility reproducing the essential features of a medium-size aero engine. The forerunner of this work was published. It was concerned with the examination of a squeeze-film damper in series with housing flexibility when supporting a rotor. The structure represented to a limited extent the essentials of the projected Rolls Royce RB401 engine. That research demonstrated the ability to calculate the oil-film forces arising from the squeeze film from known motions of the bearing components and showed that the dynamics of a shaft fitted with a squeeze film bearing can be predicted reasonably accurately. An aero-engine will normally have at least two shafts and so in addition to the excitation forces which are synchronous with the rotation of one shaft, there will also be forces at other frequencies from other shafts operating on the squeeze-film damper. Theoretical and experimental work to consider severe loading of squeeze-film dampers and to include these additional effects are examined.

Isotopic studies of mariposite-bearing rocks from the south- central Mother Lode, California.

Science.gov (United States)

Kistler, R.W.; Dodge, F.C.W.; Silberman, M.L.

1983-01-01

Gold-bearing vein formation in the Mother Lode belt of the study area apparently occurred during the Early Cretaceous between 127 and 108 m.y. B.P. The hydrothermal fluids that carried the gold precipitated quartz and mariposite at approx 320oC, similar to the T of precipitation of gold-bearing quartz veins in the Allegheny district. The O- and H-isotopic composition calculated for the fluid indicate that it was similar to formation water or was metamorphic in origin. If the carbonate in the veins was in isotopic equilibrium with this same fluid, it apparently precipitated at a higher T of approx 400oC. The Sr in the carbonate is much less radiogenic than that in any known marine carbonate, but is similar in isotopic composition to that in metamorphosed mafic volcanic rocks of the general region. These mafic rocks could have been the source for the Sr in the hydrothermal veins. This observation supports the contention that the gold-mariposite-quartz-carbonate rocks were formed as an alteration product of serpentinite and other mafic igneous rocks.-A.P.

Adherence and scratching resistance of nanometric titania films

International Nuclear Information System (INIS)

Pascoali, S.; Dominguini, L.; Borges, J.B.

2012-01-01

TiO 2 films has been used to extend the wear resistance in bearing, seals for pumps and bone prostheses. In this study was analyzed the conventional hardness and scratch toughness. The scratching test equipment used was developed at the Laboratory of materials Labmat / UFSC. The tests were performed on Titania films deposited on glass plates and ceramics via reactive DC magnetron sputtering. The films were deposited by 10, 15 and 60 min. One of the samples has a titanium metal film of a few nanometers thick between the substrate and the Titania film, the oxide has been deposited for 30 min. At this rang of tests loads the deposited films show good adhesion to substrate, there was no cracking or spalling of the film. (author)

Methods of Assessing the Resource of the Crankshaft Bearing of Internal Combustion Engine Based on the Calculation of Hydro-Mechanical Characteristics

Directory of Open Access Journals (Sweden)

I.G. Levanov

2015-09-01

Full Text Available The purpose of the article is to develop a tool to assess the theoretical resource crankshaft bearings of internal combustion engine. As a result, two methods for evaluating of the theoretical resource crankshaft bearings have been developed on the basis of the calculation of hydro-mechanical characteristics of bearings: the minimum film thickness and the extent of the zone of boundary friction. Under the theoretical resource of crankshaft bearing it is understood that during his work an increase of the radial clearance in the area of potential exposure (boundary friction is over the limit. The first technique is based on the bearing life dependence on the ratio between the minimum film thickness and its maximum allowable value. The second technique is based on the molecular-mechanical theory of friction and wear fatigue theory. Thus, these techniques may be used to estimate the resource of the crankshaft journal bearings at the design and finishing stage. However, some parameters of mathematical models have to be determined from the experimental test. The use of molecular-mechanical theory of friction and wear fatigue theory takes into account the influence of the physical and mechanical properties of a bearing material on his life.

The fluid dynamics of the chocolate fountain

Science.gov (United States)

Townsend, Adam K.; Wilson, Helen J.

2016-01-01

We consider the fluid dynamics of the chocolate fountain. Molten chocolate is a mildly shear-thinning non-Newtonian fluid. Dividing the flow into three main domains—the pumped flow up the centre, the film flow over each dome, and the freely falling curtain flow between the domes—we generate a wide-ranging study of Newtonian and non-Newtonian fluid mechanics. The central pumped flow is a benchmark to elucidate the effects of shear-thinning. The dome flow can be modelled as a thin-film flow with the leading-order effects being a simple balance of gravity and viscosity. Finally, the curtain flow is analytically intractable but is related to the existing theory of water bells (both inviscid and viscous). In pipe flow, Newtonian fluids exhibit a parabolic velocity profile; shear-thinning makes the profile more blunted. In thin-film flow over the dome, gravitational and viscous effects balance and the dome shape is not important beyond the local slope. We find that the chocolate thins and slows down as it travels down the dome. Finally, in the curtain flow, we predict the shape of the falling sheet for an inviscid fluid, and compare this with the literature to predict the shape for a viscous fluid, having shown that viscous forces are too great to ignore. We also find that the primary effect driving the shape of the curtain (which falls inwards towards the axis of the fountain) is surface tension. We find that the three domains provide excellent introductions to non-Newtonian mechanics, the important mathematical technique of scaling, and how to manipulate existing data to make our own predictions. We also find that the topic generates interest among the public in our engagement work.

The fluid dynamics of the chocolate fountain

International Nuclear Information System (INIS)

Townsend, Adam K; Wilson, Helen J

2016-01-01

We consider the fluid dynamics of the chocolate fountain. Molten chocolate is a mildly shear-thinning non-Newtonian fluid. Dividing the flow into three main domains—the pumped flow up the centre, the film flow over each dome, and the freely falling curtain flow between the domes—we generate a wide-ranging study of Newtonian and non-Newtonian fluid mechanics. The central pumped flow is a benchmark to elucidate the effects of shear-thinning. The dome flow can be modelled as a thin-film flow with the leading-order effects being a simple balance of gravity and viscosity. Finally, the curtain flow is analytically intractable but is related to the existing theory of water bells (both inviscid and viscous). In pipe flow, Newtonian fluids exhibit a parabolic velocity profile; shear-thinning makes the profile more blunted. In thin-film flow over the dome, gravitational and viscous effects balance and the dome shape is not important beyond the local slope. We find that the chocolate thins and slows down as it travels down the dome. Finally, in the curtain flow, we predict the shape of the falling sheet for an inviscid fluid, and compare this with the literature to predict the shape for a viscous fluid, having shown that viscous forces are too great to ignore. We also find that the primary effect driving the shape of the curtain (which falls inwards towards the axis of the fountain) is surface tension. We find that the three domains provide excellent introductions to non-Newtonian mechanics, the important mathematical technique of scaling, and how to manipulate existing data to make our own predictions. We also find that the topic generates interest among the public in our engagement work. (paper)

Determining minimum lubrication film for machine parts

Science.gov (United States)

Hamrock, B. J.; Dowson, D.

1978-01-01

Formula predicts minimum film thickness required for fully-flooded ball bearings, gears, and cams. Formula is result of study to determine complete theoretical solution of isothermal elasto-hydrodynamic lubrication of fully-flooded elliptical contacts.

Ex vivo evaluation of biodegradable poly(ε-caprolactone) films in digestive fluids

Energy Technology Data Exchange (ETDEWEB)

Chang, Hao-Ming [Division of General Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei 100, Taiwan, ROC (China); Prasannan, Adhimoorthy [Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 106, Taiwan, ROC (China); Tsai, Hsieh-Chih, E-mail: h.c.tsai@mail.ntust.edu.tw [Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 106, Taiwan, ROC (China); Jhu, Jheng-Jun [Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei 106, Taiwan, ROC (China)

2014-09-15

Graphical abstract: The biodegradable poly(ε-caprolactone) (PCL) films in several digestive glands using films formed from a solution of PCL in dichloromethane and ether. The PCL films degraded very differently in different digestive glands while they continued to undergo hydrolysis. - Highlights: • Hydrolytic and protein enzymatic degradation of PCL films were studied in terms of weight loss, and the degraded films were characterized using SEM, TGA, FTIR, and DSC. • Degradation of the PCL films in saliva and gastric juice was followed by superficial erosion, while the degradation of the PCL films immersed in bile and PBS was followed by bulk erosion. • For all degraded PCL films, degradation began in the amorphous regions of the films and the fraction of crystalline PCL increased slightly. - Abstract: Successful application of biodegradable implants in the gastrointestinal tract requires intensive research to understand their degradation behavior. We studied biodegradable poly(ε-caprolactone) (PCL) films in several digestive glands using films formed from a solution of PCL in dichloromethane and ether. Examination of the film morphology showed that solvent evaporation resulted in the formation of a smooth and flat surface. In addition, our results revealed that the PCL films degraded very differently in different digestive glands while they continued to undergo hydrolysis. There was also significant weight loss in the PCL films in saliva and gastric juice, which indicates that the degradation was sensitive to protein enzymes. Deconstruction of the PCL film was first discovered when it was incubated with saliva for 6 weeks. These results indicate that the degradation by saliva was mainly responsible for the enzymatic erosion of the film, which was confirmed by scanning electron microscopy.

Fluid inclusion characteristics and geological significance of the Dajinshan W-Sn polymetallic deposit in Yunfu, Guangdong Province

Science.gov (United States)

Yu, Zhangfa; Chen, Maohong; Zhao, Haijie

2015-05-01

The Dajinshan tungsten-tin polymetallic deposit is a quartz-vein-type ore deposit located in Western Guangdong Province. The ore bodies show a fairly simple shape and mainly occur as tungsten-tin polymetallic-bearing sulfide quartz veins, including quartz vein, quartz-greisens, and sulfide quartz veins, and their distribution is spatially related to Dajinshan granitoids. The formation of the deposit experienced three stages: a wolframite-molybdenite-quartz stage, a wolframite-cassiterite-sulfide-quartz stage, and a fluorite-calcite-carbonate stage. Based on detailed petrographic observations, we conducted microthermometric and Raman microspectroscopic studies of fluid inclusions formed at different ore-forming stages in the Dajinshan tungsten-tin polymetallic deposit, identifying four dominant types of fluid inclusions: aqueous two-phase inclusions, CO2-bearing inclusions, solid or daughter mineral-bearing inclusions, and gas-rich inclusions. The gas compositions of ore-forming fluids in the Dajinshan tungsten-tin polymetallic deposit are mostly CO2, CH4, and H2O. The hydrogen, oxygen, and sulfur isotopic data imply that the ore-forming fluids in the Dajinshan tungsten-tin polymetallic deposit were mainly derived from magmatic fluids, mixed with meteoric water in the ore-formation process. These results indicate that the fluid mixing and boiling led to the decomposition of the metal complex in ore-forming fluids and ore deposition.

Bearing system

Science.gov (United States)

Kapich, Davorin D.

1987-01-01

A bearing system includes backup bearings for supporting a rotating shaft upon failure of primary bearings. In the preferred embodiment, the backup bearings are rolling element bearings having their rolling elements disposed out of contact with their associated respective inner races during normal functioning of the primary bearings. Displacement detection sensors are provided for detecting displacement of the shaft upon failure of the primary bearings. Upon detection of the failure of the primary bearings, the rolling elements and inner races of the backup bearings are brought into mutual contact by axial displacement of the shaft.

Tribology experiment. [journal bearings and liquid lubricants

Science.gov (United States)

Wall, W. A.

1981-01-01

A two-dimensional concept for Spacelab rack 7 was developed to study the interaction of liquid lubricants and surfaces under static and dynamic conditions in a low-gravity environment fluid wetting and spreading experiments of a journal bearing experiments, and means to accurately measure and record the low-gravity environment during experimentation are planned. The wetting and spreading process of selected commercial lubricants on representative surface are to the observes in a near-zero gravity environment.

Geology, mineralogy and ore fluid characteristics of the Masjed Daghi gold bearing veins system, NW Iran

Directory of Open Access Journals (Sweden)

Susan Ebrahimi

2017-11-01

Full Text Available Introduction The Masjed- Daghi gold deposit lies in an area of widespread Cenozoic volcanic and plutonic rocks at the intersection of the Alborz- Azarbaijan and Urumieh- Dokhtar belts. The area was covered by a detailed exploration program, including geological maps at 1:1,000 scales (~8 km², several hundred meters of trenches and systematic sampling for Au, Ag, Pb, Zn, Cu, As, Hg analysis, and 16 diamond drill holes at a total of 1200 meters (Mohammadi et al, 2005. The vein type gold deposit in Masjed- Daghi is closely associated with a porphyry type Cu-Au deposit. Our study focuses on the gold bearing veins system in an attempt to understand the characteristics of ore fluids and mechanisms of ore formation, and to develop exploration criteria for Masjed Daghi and similar occurrences in Alborz and other Cenozoic magmatic assemblages in Iran. Materials and methods Various rock types, alteration assemblages and mineral parageneses were characterized by transmitting and reflected light microscopy, X-ray diffraction (XRD and electron microprobe analysis. Microprobe analyses were performed using a JEOL 8600 Superprobe electron microprobe at Saskatchewan University. Operating conditions were an accelerating voltage of 15 kV and a beam current of 50 nA. Representative samples from drill holes were selected for fluid inclusion studies. Fluid inclusion data were obtained using a fluid Inc. adapted USGS gas flow heating and freezing system at the Department of Geological Science at the University of Saskatchewan, Canada. To investigate the source of ore fluids, representative sulfidic samples from drill holes were selected for sulfur isotope studies. Isotopic analyses were performed using a Thermo Finnigan DeltaPlus at the G.G. Hatch Stable Isotope Laboratories, University of Ottawa. The standard error of analyses is less than ±0.1 per mil. Results Auriferous quartz veins in Masjed- Daghi are associated with porphyry style mineralization. Various

Effect of boundary conditions on the performances of gas-lubricated micro journal bearing

International Nuclear Information System (INIS)

Wang Sheng; Lei Kangbin; Kiwamu, Kase; Luo Xilian; Gu Zhaolin

2010-01-01

As significant components of micromechanics, gas-lubricated microbearings are more prevalent for their special advantages than other types. The fluid dynamics of the microbearing is different from their larger cousins due to the noncontinuum effect and surface-dominated effect, which may make the Navier-Stokes equations invalid. In this paper, by considering the accommodation coefficients on journal (α i ) and that on bearing (α o ) separately, the microbearings with different bearing numbers under the assumption of large L/D (length to diameter) are simulated using direct simulation Monte Carlo (DSMC) program incorporated with a Volume-CAD software. The diffuse reflection model and Cercignani-Lampis-Lord (CLL) model are applied to model the molecule-surface interaction. The flow field characteristics, as well as the performances of gas-lubricated journal bearings including load-carrying capacity, attitude angle and bearing drag are obtained. The results reveal that α i and α o have different effects to flow field characteristics and bearing performances. The bearing number has significantly impact on the bearing performances. The method developed in this paper would be very useful for designing and evaluating the gas-lubricated journal microbearing.

Thickness of residual wetting film in liquid-liquid displacement

Science.gov (United States)

Beresnev, Igor; Gaul, William; Vigil, R. Dennis

2011-08-01

Core-annular flow is common in nature, representing, for example, how streams of oil, surrounded by water, move in petroleum reservoirs. Oil, typically a nonwetting fluid, tends to occupy the middle (core) part of a channel, while water forms a surrounding wall-wetting film. What is the thickness of the wetting film? A classic theory has been in existence for nearly 50 years offering a solution, although in a controversial manner, for moving gas bubbles. On the other hand, an acceptable, experimentally verified theory for a body of one liquid flowing in another has not been available. Here we develop a hydrodynamic, testable theory providing an explicit relationship between the thickness of the wetting film and fluid properties for a blob of one fluid moving in another, with neither phase being gas. In its relationship to the capillary number Ca, the thickness of the film is predicted to be proportional to Ca2 at lower Ca and to level off at a constant value of ˜20% the channel radius at higher Ca. The thickness of the film is deduced to be approximately unaffected by the viscosity ratio of the fluids. We have conducted our own laboratory experiments and compiled experimental data from other studies, all of which are mutually consistent and confirm the salient features of the theory. At the same time, the classic law, originally deduced for films surrounding moving gas bubbles but often believed to hold for liquids as well, fails to explain the observations.

Dryout power of a CANFLEX bundle string with raised bearing pads

International Nuclear Information System (INIS)

Leung, L.K.H.; Dimmick, G.R.; Bullock, D.E.; Inch, W.W.R.; Jun, J.S.; Suk, H.C.

2001-01-01

Dryout power data have been obtained with CANFLEX bundle strings equipped with raised bearing pads (1.7 mm and 1.8 mm height as compared to 1.4 mm in the current Mk-IV design) at Stern Laboratories. The experiment covered a wide range of steam-water flow conditions in three flow tubes simulating uncrept, and 3.3% and 5.1% crept profiles. The dryout power follows consistent parametric trends: it increases with increasing mass-flow rate, and decreases with increasing pressure, inlet-fluid temperature and channel creep. Local and boiling-length-average (BLA) critical-heat-flux (CHF) values were evaluated from the dryout-power measurements. The dryout power and BLA CHF values of the high bearing-pad bundles are higher than those of the low bearing-pad bundles at the same channel inlet flow conditions. On average, the dryout powers for bundles with 1.7 mm and 1.8 mm bearing pads are about 8% and 10%, respectively, higher than those for the bundle with 1.4 mm bearing pads. Compared to the 37-element bundle, an enhancement in dryout power is shown with CANFLEX bundles for all bearing-pad heights, at flow conditions of interest for reactor licensing. The average dryout power enhancement varies from 4% for the CANFLEX bundle with 1.4 mm bearing pads in the uncrept channel to 27% for the CANFLEX bundle with 1.8 mm bearing pads in the 5.1% crept channel. (author)

Analysis of Space Station Centrifuge Rotor Bearing Systems: A Case Study

Science.gov (United States)

Poplawski, Joseph V.; Loewenthal, Stuart H.; Oswald, Fred B.; Zaretsky, Erwin V.; Morales, Wilfredo; Street, Kenneth W., Jr.

2014-01-01

A team of NASA bearing and lubrication experts was assembled to assess the risk for the rolling-element bearings used in the International Space Station (ISS) centrifuge rotor (CR) to seize or otherwise fail to survive for the required 10-year life. The CR was designed by the Japan Aerospace Exploration Agency and their subcontractor, NEC Toshiba Space Systems, Ltd. (NTSpace). The NASA team performed a design audit for the most critical rolling-element bearing systems and reviewed the lubricant selected. There is uncertainty regarding the ability of the Braycote 601 grease (Castrol Limited) to reliably provide the 10-year continuous life required without relubrication of the system. The fatigue life of the Rotor Shaft Assembly (RSA) spring loaded face-to-face mount at a 99-percent probability of survival (L1 life) for the ball bearing set was estimated at 700 million hours and the single ball bearing (Row 3) at 58 million hours. These lives satisfy the mission requirements for fatigue. Rolling-element seizure tests on the RSA and fluid slip joint bearings were found unlikely to stop the centrifuge, which can cause damage to the ISS structure. The spin motor encoder duplex angular-contact ball bearings have a hard preload and a large number of small balls have the highest risk of failure. These bearings were not tested for seizure even though they are less tolerant to debris or internal clearance reductions.

Fluid inclusion and stable isotopes studies of epithermal gold-bearing veins in the SE Afar Rift (Djibouti)

Science.gov (United States)

Moussa, N.; Boiron, M. C.; Grassineau, N.; Fouquet, Y.; Le Gall, B.; Mohamed, J.

2015-12-01

The Afar rift results from the interaction of a number of actively-propagating tectono-magmatic axes. Recent field investigations in the SE Afar rift have emphasized the importance of hydrothermal system in rift-related volcanic complexes. Mineralization occur as gold-silver bearing veins and are associated with felsic volcanism. Late carbonate veins barren of sulfides and gold are common. The morphologies and textures of quartz show crustiform colloform banding, massive and breccias. Microthermometric measurements were made on quartz-hosted two phases (liquid + vapor) inclusions; mean homogenization temperature range from 150°C to 340°C and ice-melting temperatures range from -0.2° to 1.6°C indicating that inclusion solutions are dilute and contain 0.35 to 2.7 equivalent wt. % NaCl. Furthermore, δ18O and δ13C values from calcite range from 3.7 to 26.6 ‰ and -7.5 to 0.3‰, respectively. The presence of platy calcite and adularia indicate that boiling condition existed. This study shows that precious-metal deposition mainly occurred from hydrothermal fluids at 200°C at around 300 and 450 m below the present-day surface in a typical low-sulphidation epithermal environment.

Analysis of image factors of x-ray films : study for the intelligent replenishment system of automatic film processor

Energy Technology Data Exchange (ETDEWEB)

Park, Sung Tae; Yoon, Chong Hyun; Park, Kwang BO; Auh, Yong Ho; Lee, Hyoung Jin; In, Kyung Hwan; Kim, Keon Chung [Asan Medical Center, Ulsan Univ. College of Medicine, Ulsan (Korea, Republic of)

1998-06-01

We analyzed image factors to determine the characteristic factors that need for intelligent replenishment system of the auto film processor. We processed the serial 300 sheets of radiographic films of chest phantom without replenishment of developing and fixation replenisher. We took the digital data by using film digitizer which scanned the films and automatically summed up the pixel values of the films. We analyzed characteristic curves, average gradients and relative speeds of individual film using densitometer and step densitometry. We also evaluated the pH of developer, fixer, and washer fluid with digital pH meter. Fixer residual rate and washing effect were measured by densitometer using the reagent methods. There was no significant reduction of the digital density numbers of the serial films without replenishment of developer and fixer. The average gradients were gradually decreased by 0.02 and relative speeds were also gradually decreased by 6.96% relative to initial standard step-densitometric measurement. The pHs of developer and fixer were reflected the inactivation of each fluid. The fixer residual rates and washing effects after processing each 25 sheets of films were in the normal range. We suggest that the digital data are not reliable due to limitation of the hardware and software of the film digitizer. We conclude that average gradient and relative speed which mean the film's contrast and sensitivity respectively are reliable factors for determining the need for the replenishment of the auto film processor. We need more study of simpler equations and programming for more intelligent replenishment system of the auto film processor.

Boundary lubrication of bearing steel in water-based lubricants with functional additives

NARCIS (Netherlands)

Wu, Y.

2017-01-01

This thesis focuses on the effect of additives on boundary lubrication of bearing steel for water-based lubrication systems. The oil-in-water (O/W) emulsion and the water-glycol based liquid were selected as the base fluids for research. Sulfur compounds, nitrogen heterocycles and graphene

Characteristic Analysis and Simulated Test of Hybrid Bearing with the Introduction of Piezoelectric Controller

Directory of Open Access Journals (Sweden)

Runlin Chen

2016-01-01

Full Text Available A novel hybrid bearing with the introduction of piezoelectric controller and tilting pads to control vibration actively is proposed in this paper, and the feasibility of this scheme is verified by theoretical calculation and experimental data. This scheme can control the vibration of bearing actively by using the electromechanical characteristics of piezoelectric ceramic transducer (PZT components. The static internal character of PZT and static external characteristic of piezoelectric control component are analyzed, and the calculation equations of preload coefficient and driving force of the new bearing are given. The simulation setup of the new bearing is designed and developed. The data representing the relationship of displacement of pad pivot, driving force, voltage, and the simulation stiffness of liquid film are obtained in the test, and the feature parameters of piezoelectric control component are amended to analyze the relationship between preload coefficient of the bearing and driving voltage. The proposed new bearing has the function of controlling preload actively. The theoretical and experimental research results provide essential guidance for the detail design of this new bearing and also provide a new idea for the vibration control of high speed rotor systems.

Journal bearing

Science.gov (United States)

Menke, John R.; Boeker, Gilbert F.

1976-05-11

1. An improved journal bearing comprising in combination a non-rotatable cylindrical bearing member having a first bearing surface, a rotatable cylindrical bearing member having a confronting second bearing surface having a plurality of bearing elements, a source of lubricant adjacent said bearing elements for supplying lubricant thereto, each bearing element consisting of a pair of elongated relatively shallowly depressed surfaces lying in a cylindrical surface co-axial with the non-depressed surface and diverging from one another in the direction of rotation and obliquely arranged with respect to the axis of rotation of said rotatable member to cause a flow of lubricant longitudinally along said depressed surfaces from their distal ends toward their proximal ends as said bearing members are rotated relative to one another, each depressed surface subtending a radial angle of less than 360.degree., and means for rotating said rotatable bearing member to cause the lubricant to flow across and along said depressed surfaces, the flow of lubricant being impeded by the non-depressed portions of said second bearing surface to cause an increase in the lubricant pressure.

Annual review of fluid mechanics. Volume 23

International Nuclear Information System (INIS)

Lumley, J.L.; Van Dyke, M.; Reed, H.L.

1991-01-01

Recent advances in theoretical, experimental, and computational fluid mechanics are discussed in a collection of annual review essays. Topics addressed include Lagrangian ocean studies, drag reduction in nature, the hydraulics of rotating strait and sill flow, analytical methods for the development of Reynolds-stress closures in turbulence, and exact solutions of the Navier-Stokes equations. Consideration is given to the theory of hurricanes, flow phenomena in CVD of thin films, particle-imaging techniques for experimental fluid mechanics, symmetry and symmetry-breaking bifurcations in fluid dynamics, turbulent mixing in stratified fluids, numerical simulation of transition in wall-bounded shear flows, fractals and multifractals in fluid turbulence, and coherent motions in the turbulent boundary layer

Camshaft bearing arrangement

Energy Technology Data Exchange (ETDEWEB)

Aoi, K.; Ozawa, T.

1986-06-10

A bearing arrangement is described for the camshaft of an internal combustion engine or the like which camshaft is formed along its length in axial order with a first bearing surface, a first cam lobe, a second bearing surface, a second cam lobe, a third bearing surface, a third cam lobe and a fourth bearing surface, the improvement comprising first bearing means extending around substantially the full circumference of the first bearing surface and journaling the first bearing surface, second bearing means extending around substantially less than the circumference of the second bearing surface and journaling the second bearing surface, third bearing means extending around substantially less than the circumference of the third bearing surface and journaling the third bearing surface, and fourth bearing means extending around substantially the full circumference of the fourth bearing surface and journaling the first bearing surface.

Magnetic fluid seals for DWDM filter manufacturing

International Nuclear Information System (INIS)

Li Zhixin

2002-01-01

Performance requirements of rotary magnetic fluid seals for thin film dense wavelength division multiplexing filter manufacturing are discussed. High speed, large diameter, tight tolerance for rotating accuracy and motion control are some of the technical challenges in this application. Analytical methods for studying these technical issues and experimental data are presented. Innovative design approaches are also discussed. It is shown that using the most advanced magnetic fluid technology and seal design technology, magnetic fluid seals can provide satisfactory performance in this challenging new application

Influence of processing medium on frictional wear properties of ball bearing steel prepared by laser surface melting coupled with bionic principles

International Nuclear Information System (INIS)

Zhou Hong; Wang Chengtao; Guo Qingchun; Yu Jiaxiang; Wang Mingxing; Liao Xunlong; Zhao Yu; Ren Luquan

2010-01-01

Coupling with bionic principles, an attempt to improve the wear resistance of ball bearing steel (GCr15) with biomimetic units on the surface was made using a pulsed Nd: YAG laser. Air and water film was employed as processing medium, respectively. The microstructures of biomimeitc units were examined by scanning electron microscope and X-ray diffraction was used to describe the microstructure and identify the phases as functions of different mediums as well as water film with different thicknesses. The results indicated that the microstructure zones in the biomimetic specimens processed with water film were more refined and had better wear resistance increased by 55.8% in comparison with that processed in air; a significant improvement in microhardness was achieved by laser surface melting. The application of water film provided considerable microstructural changes and much more regular grain shape in biomimetic units, which played a key role in improving the wear resistance of ball bearing steel.

[Which hip articulation bearing for which patient? : Tribology of the future].

Science.gov (United States)

Morlock, M M; Bishop, N; Kaddick, C

2011-12-01

Replacement of the hip joint has become an exceptionally successful procedure since the inauguration of the low friction principle by Charnley. Aseptic osteolysis and joint dislocation have been addressed by the development of wear-optimized materials and the introduction of larger heads. As an increase in head diameter against polyethylene causes wear increase, larger hard-on-hard bearings were introduced, which exhibit reduced wear and reduced dislocation risk with increasing head diameter. These findings were derived from standard simulator testing, not sufficiently considering the risk of fluid film breakdown under adverse conditions, which can cause a dramatic increase in wear and friction proportional to the head diameter. Such adverse conditions can occur clinically in patients due to several factors and have caused the presently observed unexpected problems with these new designs. Standardized preclinical testing has to be viewed as a minimum requirement but certainly not as a guarantee for the clinical success of new materials and designs even if the testing is adapted to the current patient requirements, which is presently not the case. The future of tribology lies in the prevention of adverse conditions in patients, the improvement and optimized use of proven existing materials and not in the use of new materials.

The Development of Open Water-lubricated Polycrystalline Diamond (PCD) Thrust Bearings for Use in Marine Hydrokinetic (MHK) Energy Machines

Energy Technology Data Exchange (ETDEWEB)

Cooley, Craig, H.; Khonsari, Michael,, M; Lingwall, Brent

2012-11-28

Polycrstalline diamond (PCD) bearings were designed, fabricated and tested for marine-hydro-kinetic (MHK) application. Bearing efficiency and life were evaluated using the US Synthetic bearing test facility. Three iterations of design, build and test were conducted to arrive at the best bearing design. In addition life testing that simulated the starting and stopping and the loading of real MHK applications were performed. Results showed polycrystalline diamond bearings are well suited for MHK applications and that diamond bearing technology is TRL4 ready. Based on life tests results bearing life is estimated to be at least 11.5 years. A calculation method for evaluating the performance of diamond bearings of round geometry was also investigated and developed. Finally, as part of this effort test bearings were supplied free of charge to the University of Alaska for further evaluation. The University of Alaska test program will subject the diamond bearings to sediment laden lubricating fluid.

Realization of hydrodynamic experiments on quasi-2D liquid crystal films in microgravity

Science.gov (United States)

Clark, Noel A.; Eremin, Alexey; Glaser, Matthew A.; Hall, Nancy; Harth, Kirsten; Klopp, Christoph; Maclennan, Joseph E.; Park, Cheol S.; Stannarius, Ralf; Tin, Padetha; Thurmes, William N.; Trittel, Torsten

2017-08-01

Freely suspended films of smectic liquid crystals are unique examples of quasi two-dimensional fluids. Mechanically stable and with quantized thickness of the order of only a few molecular layers, smectic films are ideal systems for studying fundamental fluid physics, such as collective molecular ordering, defect and fluctuation phenomena, hydrodynamics, and nonequilibrium behavior in two dimensions (2D), including serving as models of complex biological membranes. Smectic films can be drawn across openings in planar supports resulting in thin, meniscus-bounded membranes, and can also be prepared as bubbles, either supported on an inflation tube or floating freely. The quantized layering renders smectic films uniquely useful in 2D fluid physics. The OASIS team has pursued a variety of ground-based and microgravity applications of thin liquid crystal films to fluid structure and hydrodynamic problems in 2D and quasi-2D systems. Parabolic flights and sounding rocket experiments were carried out in order to explore the shape evolution of free floating smectic bubbles, and to probe Marangoni effects in flat films. The dynamics of emulsions of smectic islands (thicker regions on thin background films) and of microdroplet inclusions in spherical films, as well as thermocapillary effects, were studied over extended periods within the OASIS (Observation and Analysis of Smectic Islands in Space) project on the International Space Station. We summarize the technical details of the OASIS hardware and give preliminary examples of key observations.

The fluid inclusion study in petroleum exploration; O estudo de inclusoes fluidas na exploracao de petroleo

Energy Technology Data Exchange (ETDEWEB)

Coelho, Carlos Eduardo Silva [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas. Gerencia da Geoquimica]. E-mail: cescoelho@petrobras.com.br

2005-05-01

Several oil companies and research centers have been studying petroleum fluid inclusions in reservoirs since the 1980's. The first works have used the fluid inclusion microthermometry technique in order to interpret the thermal history and petroleum migration in relation to the burial history and diagenesis. Lately, the micro thermometric data is being used as a calibration parameter for thermal history modeling in sedimentary basins and reservoirs. Recently, new fluid inclusion study techniques are being used in petroleum exploration. Geochemical data of low molecular weight (up to C{sub 15}) oil-bearing fluid inclusions has been used with the purpose of pinpointing oil-bearing intervals in wells that have not revealed the presence of oil by conventional techniques. Molecular geochemical analyses of oils inside the inclusions technique enable oil-source correlations, oil-oil correlations, and maturity determination. (author)

Comparison Between Oil-mist and Oil-jet Lubrication of High-speed, Small-bore, Angular-contact Ball Bearings

Science.gov (United States)

Pinel, Stanley I.; Signer, Hans R.; Zaretsky, Erwin V.

2001-01-01

Parametric tests were conducted with an optimized 35-mm-bore-angular-contact ball bearing on a high-speed, high-temperature bearing tester. Results from both air-oil mist lubrication and oil-jet lubrication systems used to lubricate the bearing were compared to speeds of 2.5 x 10(exp 6) DN. The maximum obtainable speed with air-oil mist lubrication is 2.5 x 10(exp 6) DN. Lower bearing temperatures and higher power losses are obtained with oil-jet lubrication than with air-oil mist lubrication. Bearing power loss is a direct function of oil flow to the bearing and independent of oil delivery system. For a given oil-flow rate, bearing temperature and power loss increase with increases in speed. Bearing life is an inverse function of temperature, the difference in temperature between the individual bearing ring components, and the resultant elastohydrodynamic (EHD) film thicknesses. Bearing life is independent of the oil delivery system except as it affects temperature. Cage slip increased with increases in speed. Cage slip as high as 7 percent was measured and was generally higher with air-oil mist lubrication than with oil-jet lubrication.

Fluid Characteristics in the Giant Quartz Reef System of the Bundelkhand Craton, India: Constraints from Fluid Inclusion Study

Science.gov (United States)

Rout, D.; Panigrahi, M. K.; Pati, J. K.

2017-12-01

Giant quartz reefs are anomalous features indicating extensive mobilization of silica in the crust. Such reefs in the Abitibi belt, Canada and elsewhere are believed to be the result of activity of fluid of diverse sources on terrain boundaries. The Bundelkhand granitoid complex constituting a major part of the Bundelkhnad Craton in north-Central India is traversed by numerous such quartz reefs all across for a length of about 500 km. There are about 20 major reefs having dimensions of 35 to 40 km in length, 50 to 60 m in width standing out as prominent ridges in the region. Almost all are aligned parallel to each other in a sub-vertical to vertical manner following the NE-SW to NNE-SSW trend. Fluid inclusion petrography in quartz from these reefs reveal four types of inclusions viz. aqueous biphase (type-I), pure carbonic (type-II), aqueous carbonic (type-III) and polyphase (type-IV) inclusions. The type-I aqueous biphase inclusions are the dominant type in all the samples studied so far. Salinities calculated from temperature of melting of last ice (Tm) values are low to moderate, ranging from 0.18 to 18.19 wt% NaCl equivalents. Temperature of liquid-vapor homogenization (Th) values of these inclusions show a wide range from 101 ºC to 386 ºC (cluster around 150-250 ºC) essentially into liquid phase ruling out boiling during its course of evolution. Besides, aqueous Biphase inclusions, some data on pure CO2 inclusions furnish a near constant value of TmCO2 at -56.6 ºC in the Bundelkhand Craton indicating absence of CH4. Bivariate plot between Th and salinity suggest three possible water types which are controlling the overall activity of fluid in quartz reefs of Bundelkhand Craton viz. low-T low saline, high-T low saline and moderate-T and moderate saline. A low saline and CO2-bearing and higher temperature nature resembles a metamorphic fluid that may be a source for these giant quartz reefs. The low temperature low-salinity component could be a meteoric

Fluid-structure interactions of photo-responsive polymer cantilevers

Science.gov (United States)

Bin, Jonghoon; Oates, William S.; Yousuff Hussaini, M.

2013-02-01

A new class of photomechanical liquid crystal networks (LCNs) has emerged, which generate large bending deformation and fast response times that scale with the resonance of the polymer films. Here, a numerical study is presented that describes the photomechanical structural dynamic behavior of an LCN in a fluid medium; however, the methodology is also applicable to fluid-structure interactions of a broader range of adaptive structures. Here, we simulate the oscillation of photomechanical cantilevers excited by light while simultaneously modeling the effect of the surrounding fluid at different ambient pressures. The photoactuated LCN is modeled as an elastic thin cantilever plate, and gradients in photostrain from the external light are computed from the assumptions of light absorption and photoisomerization through the film thickness. Numerical approximations of the equations governing the plate are based on cubic B-spline shape functions and a second order implicit Newmark central scheme for time integration. For the fluid, three dimensional unsteady incompressible Navier-Stokes equations are solved using the arbitrary Lagrangian-Eulerian (ALE) method, which employs a structured body-fitted curvilinear coordinate system where the solid-fluid interface is a mesh line of the system, and the complicated interface boundary conditions are accommodated in a conventional finite-volume formulation. Numerical examples are given which provide new insight into material behavior in a fluid medium as a function of ambient pressure.

Tasmanian tigers and polar bears: The documentary moving image and (species loss

Directory of Open Access Journals (Sweden)

Belinda Smaill

2015-04-01

Full Text Available In this essay I explore how two divergent examples of the nonfiction moving image can be understood in relation to the problem of representing species loss. The species that provide the platform for this consideration are the thylacine, better known as the Tasmanian tiger, and the polar bear. They represent the two contingencies of species loss: endangerment and extinction. My analysis is structured around moving images from the 1930s of the last known thylacine and the very different example of Arctic Tale (Adam Ravetch, Sarah Robertson, 2007, a ‘Disneyfied’ film that dramatises climate change and its impact on the polar bear. Species loss is frequently perceived in a humanist sense, reflecting how we ‘imagine ourselves’ or anthropocentric charactersations of non-human others. I offer a close analysis of the two films, examining the problem of representing extinction through a consideration of the play of absence and presence, vitality and extinguishment, that characterises both the ontology of cinema and narratives about species loss.

Mineralogical and Fluid Inclusions Evidence For The Genesis of Umm Addebaa-Umm Kabu Beryl Belt, South Eastern Desert, Egypt

International Nuclear Information System (INIS)

Omar, S.A.M.

2016-01-01

Beryl mineralization in quartz veins and pegmatites, are common deposits of tectonic-hydrothermal and/or igneous origin. The beryl-specialized granites association at Umm Addebaa-Umm Kabu belt is manifested in the field by the development of a system of beryl-bearing pegmatitic pods and quartz veins. The emplacement of these syn-tectonic pegmatitic leucogranites from which K- and Be-rich fluid phases were derived, are confined to the shear zones, as well as a broad zone of alkali metasomatism. Microthermometic studies of primary fluid inclusions within beryl growth zones are consistent with beryl precipitation from H 2 O-CO 2 ± CH 4 bearing saline brines. The estimated fluid composition is approximately 0.88 mol% H 2 O, 0.017 mol% CO 2 ± 0.001 mol% CH 4 and 0.10 mol% NaCl (2- 11 wt.% NaCl eq.). Fluid inclusion results are consistent with that mineralization in pegmatites and quartz veins that are formed by two genetic stages. The first stage is characterized by temperature of formation in the range of 216.4 - 378.3 °C, with corresponding pressures along fluid inclusion isochore paths ranging from 1.04 to 2.25 bar. The second stage is of aqueous fluid represented with low temperature (177-255°C) and pressure ≤ 1 bar, but high saline (16-22 wt.% NaCl eq.) which might explain mixing of the early carbonaceous fluid with late meteoric water accompanied with pressure release. Thus, it can be inferred that the Be-bearing solutions were moderately saline, but CO 2 (and possible CH 4 )-rich fluid implies that Be was most probably complexed by carbonate ( + CH 4 ) - chloride base. The different paragenetic types of emerald and beryl associated with granitoid rocks indicates that the chemistry of the Be-bearing fluids (rather than that of the bulk rock), and syn-tectonic intrusions of leucogranites and pegmatites (Be deriving sources) along major ductile shear zones are the important factors controlling the crystallization of beryl.

Alignment verification in stereotactic radiosurgery with use of graphic arts film

International Nuclear Information System (INIS)

Sweet, J.; Lamba, M.

1990-01-01

This paper evaluates the use of graphic arts film for field alignment verification of linear accelerator-based stereotactic radiosurgery. The characteristic curve was generated for Fuji RO-100 graphic arts film in a standard leaded radiation therapy cassette at 6 MV. The linear portion of the curve and the film contrast are presented and their clinical advantages discussed. The high contrast of this graphic arts film improves visualization of the 5-mm ball bearing (simulated target) in small, circular treatment fields. Comparison with standard port film demonstrates the large linear range of the graphic arts film, which proved useful in visualization of the simulated target within the small, circular treatment field

Direct Monte Carlo simulation of nanoscale mixed gas bearings

Directory of Open Access Journals (Sweden)

Kyaw Sett Myo

2015-06-01

Full Text Available The conception of sealed hard drives with helium gas mixture has been recently suggested over the current hard drives for achieving higher reliability and less position error. Therefore, it is important to understand the effects of different helium gas mixtures on the slider bearing characteristics in the head–disk interface. In this article, the helium/air and helium/argon gas mixtures are applied as the working fluids and their effects on the bearing characteristics are studied using the direct simulation Monte Carlo method. Based on direct simulation Monte Carlo simulations, the physical properties of these gas mixtures such as mean free path and dynamic viscosity are achieved and compared with those obtained from theoretical models. It is observed that both results are comparable. Using these gas mixture properties, the bearing pressure distributions are calculated under different fractions of helium with conventional molecular gas lubrication models. The outcomes reveal that the molecular gas lubrication results could have relatively good agreement with those of direct simulation Monte Carlo simulations, especially for pure air, helium, or argon gas cases. For gas mixtures, the bearing pressures predicted by molecular gas lubrication model are slightly larger than those from direct simulation Monte Carlo simulation.

Nonlinear Squeeze Film Dampers without Centralized Springs

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Zhu Changsheng

2000-01-01

Full Text Available In this paper, the bifurcation behavior of a flexible rotor supported on nonlinear squeeze film dampers without centralized springs is analyzed numerically by means of rotor trajectories, Poincar maps, bifurcation diagrams and power spectra, based on the short bearing and cavitated film assumptions. It is shown that there also exist two different operations (i.e., socalled bistable operations in some speed regions in the rotor system supported on the nonlinear squeeze film dampers without centralized springs. In the bistable operation speed regions, the rotor system exhibits synchronous, sub-synchronous, sub-super-synchronous and almost-periodic as well as nonperiodic motions. The periodic bifurcation behaviors of the rotor system supported on nonlinear squeeze film dampers without centralized springs are very complex and require further investigations.

Numerical Simulation and Experimental Study on the Gas-Solid Coupling of the Aerostatic Thrust Bearing with Elastic Equalizing Pressure Groove

Directory of Open Access Journals (Sweden)

Zhao Xiao-long

2017-01-01

Full Text Available Aiming at the problem of low stiffness of aerostatic bearing, according to the principle of gas-solid coupling, this paper designs a kind of aerostatic thrust bearing with elastic equalizing pressure groove (EEPG and investigates the effect of elastic equalizing pressure groove (EEPG on the stiffness of aerostatic bearing. According to the physical model of the bearing, one deduces the deformation control equation of the elastic equalizing pressure groove and the control equation of gas lubrication, using finite difference method to derive the control equations and coupling calculation. The bearing capacity and stiffness of aerostatic bearing with EEPG in different gas film clearance are obtained. The calculation results show that the stiffness increased by 59%. The results of numerical calculation and experimental results have good consistency, proving the gas-solid coupling method can improve the bearing stiffness.

Thermal conductivity of hydrate-bearing sediments

Science.gov (United States)

Cortes, Douglas D.; Martin, Ana I.; Yun, Tae Sup; Francisca, Franco M.; Santamarina, J. Carlos; Ruppel, Carolyn D.

2009-01-01

A thorough understanding of the thermal conductivity of hydrate-bearing sediments is necessary for evaluating phase transformation processes that would accompany energy production from gas hydrate deposits and for estimating regional heat flow based on the observed depth to the base of the gas hydrate stability zone. The coexistence of multiple phases (gas hydrate, liquid and gas pore fill, and solid sediment grains) and their complex spatial arrangement hinder the a priori prediction of the thermal conductivity of hydrate-bearing sediments. Previous studies have been unable to capture the full parameter space covered by variations in grain size, specific surface, degree of saturation, nature of pore filling material, and effective stress for hydrate-bearing samples. Here we report on systematic measurements of the thermal conductivity of air dry, water- and tetrohydrofuran (THF)-saturated, and THF hydrate–saturated sand and clay samples at vertical effective stress of 0.05 to 1 MPa (corresponding to depths as great as 100 m below seafloor). Results reveal that the bulk thermal conductivity of the samples in every case reflects a complex interplay among particle size, effective stress, porosity, and fluid-versus-hydrate filled pore spaces. The thermal conductivity of THF hydrate–bearing soils increases upon hydrate formation although the thermal conductivities of THF solution and THF hydrate are almost the same. Several mechanisms can contribute to this effect including cryogenic suction during hydrate crystal growth and the ensuing porosity reduction in the surrounding sediment, increased mean effective stress due to hydrate formation under zero lateral strain conditions, and decreased interface thermal impedance as grain-liquid interfaces are transformed into grain-hydrate interfaces.

Optically induced anisotropy in photo responsive sol-gel matrix bearing a silylated disperse red 1

International Nuclear Information System (INIS)

Choi, Dong Hoon; Cho, Kang Jin; Cha, Young Kwan; Oh, Sang Joon

2000-01-01

We synthesized the simple triethoxysilanes (SGDR1) bearing a disperse red 1 for thin film fabrication. The thin films were prepared using the solution of SGDR1 after hydrolysis and condensation. The films were annealed at two different temperatures such as 150.deg.C and 200.deg.C. Trans-to-cis photoisomerization was observed under the exposure of 532 nm light with UV-Vis absorption spectroscopy. The kinetic study of photoisomerization was performed in the film. Reorientation of the polar azobenzene molecules induced optical anisotropy under a linearly polarized light at 532 nm. The effect of aggregation of the chromophores and annealing of the silicon oxide in the matrix were studied on the dynamic properties of isomerization and induced birefringence

Numerical Analysis of Film Cooling at High Blowing Ratio

Science.gov (United States)

El-Gabry, Lamyaa; Heidmann, James; Ameri, Ali

2009-01-01

Computational Fluid Dynamics is used in the analysis of a film cooling jet in crossflow. Predictions of film effectiveness are compared with experimental results for a circular jet at blowing ratios ranging from 0.5 to 2.0. Film effectiveness is a surface quantity which alone is insufficient in understanding the source and finding a remedy for shortcomings of the numerical model. Therefore, in addition, comparisons are made to flow field measurements of temperature along the jet centerline. These comparisons show that the CFD model is accurately predicting the extent and trajectory of the film cooling jet; however, there is a lack of agreement in the near-wall region downstream of the film hole. The effects of main stream turbulence conditions, boundary layer thickness, turbulence modeling, and numerical artificial dissipation are evaluated and found to have an insufficient impact in the wake region of separated films (i.e. cannot account for the discrepancy between measured and predicted centerline fluid temperatures). Analyses of low and moderate blowing ratio cases are carried out and results are in good agreement with data.

Grizzly bear

Science.gov (United States)

Schwartz, C.C.; Miller, S.D.; Haroldson, M.A.; Feldhamer, G.; Thompson, B.; Chapman, J.

2003-01-01

The grizzly bear inspires fear, awe, and respect in humans to a degree unmatched by any other North American wild mammal. Like other bear species, it can inflict serious injury and death on humans and sometimes does. Unlike the polar bear (Ursus maritimus) of the sparsely inhabited northern arctic, however, grizzly bears still live in areas visited by crowds of people, where presence of the grizzly remains physically real and emotionally dominant. A hike in the wilderness that includes grizzly bears is different from a stroll in a forest from which grizzly bears have been purged; nighttime conversations around the campfire and dreams in the tent reflect the presence of the great bear. Contributing to the aura of the grizzly bear is the mixture of myth and reality about its ferocity. unpredictable disposition, large size, strength, huge canines, long claws, keen senses, swiftness, and playfulness. They share characteristics with humans such as generalist life history strategies. extended periods of maternal care, and omnivorous diets. These factors capture the human imagination in ways distinct from other North American mammals. Precontact Native American legends reflected the same fascination with the grizzly bear as modern stories and legends (Rockwell 1991).

Stability of oxidized iron species and the redox budget of slab-derived fluids

Science.gov (United States)

Sanchez-Valle, C.; Hin, R.; Testemale, D.; Borca, C.; Grolimund, D.

2017-12-01

The high oxidation state of subduction zone magmas compared to magmas from other locations might result from the influx of oxidized fluid from the subducted oceanic plate into the mantle wedge. However, the nature of the chemical agent(s) and the mechanism responsible for the transfer of the oxidized signature from the slab to the mantle wedge remains poorly understood. In this contribution, we will discuss the oxidizing capacity of slab-derived fluids in the light of experimental results of the solubility and speciation of iron in high-pressure fluids that mimic the slab flux. Iron-bearing mineral assemblages were equilibrated with chlorinated aqueous fluids and hydrous granitic melts at different oxygen fugacities relevant for the present day crust/mantle. The concentration of iron and the distribution of stability of oxidized iron species were monitored up to 2.5 GPa and 800 °C using a combination of diamond trap experiments and XANES measurements in diamond anvil cells. The results illustrate the role of coordination chemistry involving halogen and polymerized species in the stability of oxidized iron in the fluids. The concentration of Fe3+ in the fluids progressively decreases as temperature increases, regardless of fluid composition and pressure. This implies that the fluid capacity to transport Fe3+ at high temperature may be limited, even at the redox conditions relevant for the present day crust and mantle. With the new experimental results, we place constrains on the oxidizing capacity of Fe-bearing metasomatic fluids and discuss the transfer of the oxidizing signature and the conditions for the genesis of oxidized arc magmas.

Chaotic Behaviour Investigation of a Front Opposed-Hemispherical Spiral-Grooved Air Bearing System

Directory of Open Access Journals (Sweden)

Cheng-Chi Wang

2017-01-01

Full Text Available In recent years, spiral-grooved air bearing systems have attracted much attention and are especially useful in precision instruments and machines with spindles that rotate at high speed. Load support can be multidirectional and this type of bearing can also be very rigid. Studies show that some of the design problems encountered are dynamic and include critical speed, nonlinearity, gas film pressure, unbalanced rotors, and even poor design, all of which can result in the generation of chaotic aperiodic motion and instability under certain conditions. Such irregular motion on a large scale can cause severe damage to a machine or instrument. Therefore, understanding the conditions under which aperiodic behaviour and vibration arise is crucial for prevention. In this study, numerical analysis, including the Finite Difference and Differential Transformation Methods, is used to study these effects in detail in a front opposed-hemispherical spiral-grooved air bearing system. It was found that different rotor masses and bearing number could cause undesirable behaviour including periodic, subperiodic, quasi-periodic, and chaotic motion. The results obtained in this study can be used as a basis for future bearing system design and the prevention of instability.

An autopsy case related to a terrorist attack using a ball-bearing bomb.

Science.gov (United States)

Takamiya, Masataka; Biwasaka, Hitoshi; Niitsu, Hisae; Saigusa, Kiyoshi; Aoki, Yasuhiro

2009-03-01

We encountered an autopsy case related to a terrorist attack using a ball-bearing bomb. The decedent was a 51-year-old male without significant medical histories. During dinner in a restaurant, the perpetrator suddenly exploded a ball-bearing bomb, the blast from which blew the victim off his chair. The victim was found to be unresponsive, and pronounced dead. X-ray photographs taken before autopsy revealed six spherical shadows. Three penetrating wounds in the head, one in the neck and chest, and two in the left upper arm were observed in vivo. Six projectiles recovered from the body were identified as ball-bearings, one of which traveled through the midbrain, diencephalon, and left temporal lobe. Although blast injuries and penetrating wounds are often combined in bomb attack victims, penetrating brain injury would be the cause of death in this case. Lethal injuries to major organs can thus occur even though the destructive force of a ball-bearing bomb is weak. X-ray films were informative for detecting the ball-bearings in this case, suggesting that autopsy imaging is essential in cases of terrorism victims.

Ball Bearings Equipped for In Situ Lubrication on Demand

Science.gov (United States)

Marchetti, Mario; Jones, William R., Jr.; Pepper, Stephen V.; Jansen, Mark; Predmore, Roamer

2005-01-01

In situ systems that provide fresh lubricants to ball/race contacts on demand have been developed to prolong the operational lives of ball bearings. These systems were originally intended to be incorporated into ball bearings in mechanisms that are required to operate in outer space for years, in conditions in which lubricants tend to deteriorate and/or evaporate. These systems may also be useful for similarly prolonging bearing lifetimes on Earth. Reservoirs have been among the means used previously to resupply lubricants. Lubricant- resupply reservoirs are bulky and add complexity to bearing assemblies. In addition, such a reservoir cannot be turned on or off as needed: it supplies lubricant continuously, often leading to an excess of lubricant in the bearing. A lubricator of the present type includes a porous ring cartridge attached to the inner or the outer ring of a ball bearing (see Figure 1). Oil is stored in the porous cartridge and is released by heating the cartridge: Because the thermal expansion of the oil exceeds that of the cartridge, heating causes the ejection of some oil. A metal film can be deposited on a face of the cartridge to serve as an electrical-resistance heater. The heater can be activated in response to a measured increase in torque that signals depletion of oil from the bearing/race contacts. Because the oil has low surface tension and readily wets the bearing-ring material, it spreads over the bearing ring and eventually reaches the ball/race contacts. The Marangoni effect (a surface-tension gradient associated with a temperature gradient) is utilized to enhance the desired transfer of lubricant to the ball/race contacts during heating. For a test, a ball bearing designed for use at low speed was assembled without lubricant and equipped with a porous-ring lubricator, the resistance heater of which consumed a power of less than 1 W when triggered on by a torque-measuring device. In the test, a load of 20 lb (.89 N) was applied and the

Introducing Non-Newtonian Fluid Mechanics Computations with Mathematica in the Undergraduate Curriculum

Science.gov (United States)

Binous, Housam

2007-01-01

We study four non-Newtonian fluid mechanics problems using Mathematica[R]. Constitutive equations describing the behavior of power-law, Bingham and Carreau models are recalled. The velocity profile is obtained for the horizontal flow of power-law fluids in pipes and annuli. For the vertical laminar film flow of a Bingham fluid we determine the…

Investigation of SSME alternate high pressure fuel turbopump lift-off seal fluid and structural dynamic interaction

Science.gov (United States)

Elrod, David A.

1989-01-01

The Space Shuttle main engine (SSME) alternate turbopump development program (ATD) high pressure fuel turbopump (HPFTP) design utilizes an innovative lift-off seal (LOS) design that is located in close proximity to the turbine end bearing. Cooling flow exiting the bearing passes through the lift-off seal during steady state operation. The potential for fluid excitation of lift-off seal structural resonances is investigated. No fluid excitation of LOS resonances is predicted. However, if predicted LOS natural frequencies are significantly lowered by the presence of the coolant, pressure oscillations caused by synchronous whirl of the HPFTP rotor may excite a resonance.

Seminal Fluid Analysis And Biophysical Profile: Findings And ...

African Journals Online (AJOL)

Seminal Fluid Analysis And Biophysical Profile: Findings And Relevance In Infertile Males In Ilorin, Nigeria. EK Oghagbon, AAG Jimoh, SA Adebisi. Abstract. To determine if there was a bearing of body mass index (BMI) on male infertility, a cross-sectional study of males of infertile couples, attending our infertility clinic was ...

Vibration of a rotating shaft on hydrodynamic bearings: multi-scales surface effects

International Nuclear Information System (INIS)

Rebufa, Jocelyn

2016-01-01

The hydrodynamic bearing provides good damping properties in rotating machineries. However, the performances of rotor-bearings systems are highly impacted by nonlinear effects that are difficult to analyze. The rotor dynamics prediction requires advanced models for the flow in the bearings. The surface of the bearings seems to have a strong impact on the lubricant flow, acting on the static and dynamic properties of the rotating parts. This study aims to enhance the simulation of the bearings' surface state effect on the motion of the rotating shaft. The flexible shaft interacts with textured hydrodynamic bearings. Multi-scales homogenization is used in a multi-physics algorithm in order to describe the fluid-structure interaction. Different models are used to account for the cavitation phenomenon in the bearings. Nonlinear harmonic methods allow efficient parametric studies of periodic solutions as well as their stability. Moreover, a test rig has been designed to compare predictions to real measurements. Several textured shaft samples modified with femto-seconds LASER surface texturing are tested. In most cases the experimental study showed similar results than the simulation. Enhancements of the vibration behaviors of the rotor-bearing system have been revealed for certain texturing patterns. The self-excited vibration, also known as 'oil whirl' phenomenon, is stabilized on a wide rotating frequency range. However, the simulation tool does not predict well the enhancements that are observed. Vortices in surface texturing patterns have been revealed numerically with Navier-Stokes equation resolution. These results are opposed to the classical lubrication hypothesis. It is also a possible explanation of the enhancements that are experimentally measured with textured bearings. (author) [fr

Extended-gate field-effect transistor (EG-FET) with molecularly imprinted polymer (MIP) film for selective inosine determination.

Science.gov (United States)

Iskierko, Zofia; Sosnowska, Marta; Sharma, Piyush Sindhu; Benincori, Tiziana; D'Souza, Francis; Kaminska, Izabela; Fronc, Krzysztof; Noworyta, Krzysztof

2015-12-15

A novel recognition unit of chemical sensor for selective determination of the inosine, renal disfunction biomarker, was devised and prepared. For that purpose, inosine-templated molecularly imprinted polymer (MIP) film was deposited on an extended-gate field-effect transistor (EG-FET) signal transducing unit. The MIP film was prepared by electrochemical polymerization of bis(bithiophene) derivatives bearing cytosine and boronic acid substituents, in the presence of the inosine template and a thiophene cross-linker. After MIP film deposition, the template was removed, and was confirmed by UV-visible spectroscopy. Subsequently, the film composition was characterized by spectroscopic techniques, and its morphology and thickness were determined by AFM. The finally MIP film-coated extended-gate field-effect transistor (EG-FET) was used for signal transduction. This combination is not widely studied in the literature, despite the fact that it allows for facile integration of electrodeposited MIP film with FET transducer. The linear dynamic concentration range of the chemosensor was 0.5-50 μM with inosine detectability of 0.62 μM. The obtained detectability compares well to the levels of the inosine in body fluids which are in the range 0-2.9 µM for patients with diagnosed diabetic nephropathy, gout or hyperuricemia, and can reach 25 µM in certain cases. The imprinting factor for inosine, determined from piezomicrogravimetric experiments with use of the MIP film-coated quartz crystal resonator, was found to be 5.5. Higher selectivity for inosine with respect to common interferents was also achieved with the present molecularly engineered sensing element. The obtained analytical parameters of the devised chemosensor allow for its use for practical sample measurements. Copyright © 2015 Elsevier B.V. All rights reserved.

77 FR 70423 - Black Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC...

Science.gov (United States)

2012-11-26

... Bear Hydro Partners, LLC and Black Bear Development Holdings, LLC and Black Bear SO, LLC; Notice of..., 2012, Black Bear Hydro Partners, LLC, sole licensee (transferor) and Black Bear Development Holdings, LLC and Black Bear SO, LLC (transferees) filed an application for the partial the transfer of licenses...

Eclogite-associated potassic silicate melts and chloride-rich fluids in the mantle: a possible connection

Science.gov (United States)

Safonov, O.; Butvina, V.

2009-04-01

Relics of potassium-rich (4-14 wt. % of K2O and K2O/Na2O > 1.0) melts are a specific features of some partially molten diamondiferous eclogite xenoliths in kimberlites worldwide [1, 2]. In addition, potassic silicic melt inclusions with up to 16 wt. % of K2O are associated with eclogite phases in kimberlitic diamonds (O. Navon, pers. comm.). According to available experimental data, no such potassium contents can be reached by "dry" and hydrous melting of eclogite. These data point to close connection between infiltration of essentially potassic fluids, partial melting and diamond formation in mantle eclogites [2]. Among specific components of these fluids, alkali chlorides, apparently, play an important role. This conclusion follows from assemblages of the melt relics with chlorine-bearing phases in eclogite xenoliths [1], findings of KCl-rich inclusions in diamonds from the xenoliths [3], and concentration of Cl up to 0.5-1.5 wt. % in the melt inclusions in diamonds. In this presentation, we review our experimental data on reactions of KCl melts and KCl-bearing fluids with model and natural eclogite-related minerals and assemblages. Experiments in the model system jadeite(±diopside)-KCl(±H2O) at 4-7 GPa showed that, being immiscible, chloride liquids provoke a strong K-Na exchange with silicates (jadeite). As a result, low-temperature ultrapotassic chlorine-bearing (up to 3 wt. % of Cl) aluminosilicate melts form. These melts is able to produce sanidine, which is characteristic phase in some partially molten eclogites. In addition, in presence of water Si-rich Cl-bearing mica (Al-celadonite-phlogopite) crystallizes in equilibrium with sanidine and/or potassic melt and immiscible chloride liquid. This mica is similar to that observed in some eclogitic diamonds bearing chloride-rich fluid inclusions [4], as well as in diamonds in partially molten eclogites [2]. Interaction of KCl melt with pyrope garnet also produce potassic aluminosilicate melt because of high

Levitation of a drop over a film flow

Science.gov (United States)

Sreenivas, K. R.; de, P. K.; Arakeri, Jaywant H.

1999-02-01

A vertical jet of water impinging on a horizontal surface produces a radial film flow followed by a circular hydraulic jump. We report a phenomenon where fairly large (1 ml) drops of liquid levitate just upstream of the jump on a thin air layer between the drop and the film flow. We explain the phenomenon using lubrication theory. Bearing action both in the air film and the water film seems to be necessary to support large drops. Horizontal support is given to the drop by the hydraulic jump. A variety of drop shapes is observed depending on the volume of the drop and liquid properties. We show that interaction of the forces due to gravity, surface tension, viscosity and inertia produces these various shapes.

Interfacial bubbles formed by plunging thin liquid films in a pool

Science.gov (United States)

Salkin, Louis; Schmit, Alexandre; David, Richard; Delvert, Alexandre; Gicquel, Eric; Panizza, Pascal; Courbin, Laurent

2017-06-01

We show that the immersion of a horizontally suspended thin film of liquid in a pool of the same fluid creates an interfacial bubble, that is, a bubble at the liquid-air interface. Varying the fluid properties, the film's size, and its immersion velocity, our experiments unveil two formation regimes characterized by either a visco-capillary or an inertio-capillary mechanism that controls the size of a produced bubble. To rationalize these results, we compare the pressure exerted by the air flow under a plunging film with the Laplace pressure needed to generate film dimpling, which subsequently yields air entrapment and the production of a bubble. This physical model explains the power-law variations of the bubble size with the governing dimensionless number for each regime.

Discovering geothermal supercritical fluids: a new frontier for seismic exploration.

Science.gov (United States)

Piana Agostinetti, Nicola; Licciardi, Andrea; Piccinini, Davide; Mazzarini, Francesco; Musumeci, Giovanni; Saccorotti, Gilberto; Chiarabba, Claudio

2017-11-06

Exploiting supercritical geothermal resources represents a frontier for the next generation of geothermal electrical power plant, as the heat capacity of supercritical fluids (SCF),which directly impacts on energy production, is much higher than that of fluids at subcritical conditions. Reconnaissance and location of intensively permeable and productive horizons at depth is the present limit for the development of SCF geothermal plants. We use, for the first time, teleseismic converted waves (i.e. receiver function) for discovering those horizons in the crust. Thanks to the capability of receiver function to map buried anisotropic materials, the SCF-bearing horizon is seen as the 4km-depth abrupt termination of a shallow, thick, ultra-high (>30%) anisotropic rock volume, in the center of the Larderello geothermal field. The SCF-bearing horizon develops within the granites of the geothermal field, bounding at depth the vapor-filled heavily-fractured rock matrix that hosts the shallow steam-dominated geothermal reservoirs. The sharp termination at depth of the anisotropic behavior of granites, coinciding with a 2 km-thick stripe of seismicity and diffuse fracturing, points out the sudden change in compressibility of the fluid filling the fractures and is a key-evidence of deep fluids that locally traversed the supercritical conditions. The presence of SCF and fracture permeability in nominally ductile granitic rocks open new scenarios for the understanding of magmatic systems and for geothermal exploitation.

Phylogeography of mitochondrial DNA variation in brown bears and polar bears.

Science.gov (United States)

Shields, G F; Adams, D; Garner, G; Labelle, M; Pietsch, J; Ramsay, M; Schwartz, C; Titus, K; Williamson, S

2000-05-01

We analyzed 286 nucleotides of the middle portion of the mitochondrial cytochrome b gene of 61 brown bears from three locations in Alaska and 55 polar bears from Arctic Canada and Arctic Siberia to test our earlier observations of paraphyly between polar bears and brown bears as well as to test the extreme uniqueness of mitochondrial DNA types of brown bears on Admiralty, Baranof, and Chichagof (ABC) islands of southeastern Alaska. We also investigated the phylogeography of brown bears of Alaska's Kenai Peninsula in relation to other Alaskan brown bears because the former are being threatened by increased human development. We predicted that: (1) mtDNA paraphyly between brown bears and polar bears would be upheld, (2) the mtDNA uniqueness of brown bears of the ABC islands would be upheld, and (3) brown bears of the Kenai Peninsula would belong to either clade II or clade III of brown bears of our earlier studies of mtDNA. All of our predictions were upheld through the analysis of these additional samples. Copyright 2000 Academic Press.

Phylogeography of mitochondrial DNA variation in brown bears and polar bears

Science.gov (United States)

Shields, Gerald F.; Adams, Deborah; Garner, Gerald W.; Labelle, Martine; Pietsch, Jacy; Ramsay, Malcolm; Schwartz, Charles; Titus, Kimberly; Williamson, Scott

2000-01-01

We analyzed 286 nucleotides of the middle portion of the mitochondrial cytochrome b gene of 61 brown bears from three locations in Alaska and 55 polar bears from Arctic Canada and Arctic Siberia to test our earlier observations of paraphyly between polar bears and brown bears as well as to test the extreme uniqueness of mitochondrial DNA types of brown bears on Admiralty, Baranof, and Chichagof (ABC) islands of southeastern Alaska. We also investigated the phylogeography of brown bears of Alaska's Kenai Peninsula in relation to other Alaskan brown bears because the former are being threatened by increased human development. We predicted that: (1) mtDNA paraphyly between brown bears and polar bears would be upheld, (2) the mtDNA uniqueness of brown bears of the ABC islands would be upheld, and (3) brown bears of the Kenai Peninsula would belong to either clade II or clade III of brown bears of our earlier studies of mtDNA. All of our predictions were upheld through the analysis of these additional samples.

Numerical Investigation of Turbulence Models for a Superlaminar Journal Bearing

Directory of Open Access Journals (Sweden)

Aoshuang Ding

2018-01-01

Full Text Available With rotating machineries working at high speeds, oil flow in bearings becomes superlaminar. Under superlaminar conditions, flow exhibits between laminar and fully developed turbulence. In this study, superlaminar oil flow in an oil-lubricated tilting-pad journal bearing is analyzed through computational fluid dynamics (CFD. A three-dimensional bearing model is established. CFD results from the laminar model and 14 turbulence models are compared with experimental findings. The laminar simulation results of pad-side pressure are inconsistent with the experimental data. Thus, the turbulence effects on superlaminar flow should be considered. The simulated temperature and pressure distributions from the classical fully developed turbulence models cannot correctly fit the experimental data. As such, turbulence models should be corrected for superlaminar flow. However, several corrections, such as transition correction, are unsuitable. Among all the flow models, the SST model with low-Re correction exhibits the best pressure distribution and turbulence viscosity ratio. Velocity profile analysis confirms that a buffer layer plays an important role in the superlaminar boundary layer. Classical fully developed turbulence models cannot accurately predict the buffer layer, but this problem can be resolved by initiating an appropriate low-Re correction. Therefore, the SST model with low-Re correction yields suitable results for superlaminar flows in bearings.

The Biotribology of PEEK-on-HXLPE Bearings Is Comparable to Traditional Bearings on a Multidirectional Pin-on-disk Tester.

Science.gov (United States)

Baykal, Doruk; Siskey, Ryan S; Underwood, Richard J; Briscoe, Adam; Kurtz, Steven M

2016-11-01

= 0.73 mm 3 /MC, p = 0.36). Bearing couples with PEEK reinforced with a carbon fiber (CFR-PEEK) counterface had higher wear rates (14.5 ± 15.1 mm 3 /MC; 95% CI, 9.1-20.0 mm 3 /MC) than bearing couples with a PEEK (5.1 ± 3.7 mm 3 /MC; 95% CI, 3.7-6.4 mm 3 /MC) or CoCr (4.1 ± 2.7 mm 3 /MC; 95% CI, 3.2-5.1 mm 3 /MC) counterface (mean difference = 9.5 mm 3 /MC, p PEEK and HXLPE were insensitive to the cross-shear scenario in the contact mechanics (WR: 0.3 ± 0.1 mm 3 /MC for PEEK pins [95% CI, 0.2-0.3 mm 3 /MC] [representing full cross-shear condition] and 0.0 ± 1.0 mm 3 /MC for PEEK disks [95% CI, -0.5 to 0.5 mm 3 /MC] [representing limited cross-shear condition], mean difference = 0.3 mm 3 /MC, p = 0.23; WR: 1.3 ± 1.0 mm 3 /MC for HXLPE pins [95% CI, 0.7-1.9 mm 3 /MC] [full cross-shear] and 2.1 ± 2.2 mm 3 /MC for HXLPE disks [95% CI, 0.8-3.3 mm 3 /MC] [limited cross-shear], mean difference = 0.8 mm 3 /MC, p = 0.24). Qualitatively, the surface morphology of UHMWPE appeared similar with PEEK or CoCr as a counterface, although it had a rougher appearance when coupled with carbon fiber-reinforced PEEK. No transfer film was detected on the specimens. Our in vitro pin-on-disk data suggest that all-polymer bearings, especially PEEK-on-HXLPE bearing couples, may represent a viable alternative to traditional bearings with respect to their wear performance. Our results warrant further testing of all-polymer bearing couples in physiologically relevant joint simulator tests. The in vitro pin-on-disk wear resistance of all-polymer bearings incorporating PEEK-on-HXLPE warrants further investigation using joint simulator testing for their validation as useful, metal-free alternatives to traditional CoCr-on-HXLPE bearings for use in orthopaedic applications.

Density and Phase State of a Confined Nonpolar Fluid

Science.gov (United States)

Kienle, Daniel F.; Kuhl, Tonya L.

2016-07-01

Measurements of the mean refractive index of a spherelike nonpolar fluid, octamethytetracylclosiloxane (OMCTS), confined between mica sheets, demonstrate direct and conclusive experimental evidence of the absence of a first-order liquid-to-solid phase transition in the fluid when confined, which has been suggested to occur from previous experimental and simulation results. The results also show that the density remains constant throughout confinement, and that the fluid is incompressible. This, along with the observation of very large increases (many orders of magnitude) in viscosity during confinement from the literature, demonstrate that the molecular motion is limited by the confining wall and not the molecular packing. In addition, the recently developed refractive index profile correction method, which enables the structural perturbation inherent at a solid-liquid interface and that of a liquid in confinement to be determined independently, was used to show that there was no measurable excess or depleted mass of OMCTS near the mica surface in bulk films or confined films of only two molecular layers.

Superstable Ultrathin Water Film Confined in a Hydrophilized Carbon Nanotube.

Science.gov (United States)

Tomo, Yoko; Askounis, Alexandros; Ikuta, Tatsuya; Takata, Yasuyuki; Sefiane, Khellil; Takahashi, Koji

2018-03-14

Fluids confined in a nanoscale space behave differently than in the bulk due to strong interactions between fluid molecules and solid atoms. Here, we observed water confined inside "open" hydrophilized carbon nanotubes (CNT), with diameter of tens of nanometers, using transmission electron microscopy (TEM). A 1-7 nm water film adhering to most of the inner wall surface was observed and remained stable in the high vacuum (order of 10 -5 Pa) of the TEM. The superstability of this film was attributed to a combination of curvature, nanoroughness, and confinement resulting in a lower vapor pressure for water and hence inhibiting its vaporization. Occasional, suspended ultrathin water film with thickness of 3-20 nm were found and remained stable inside the CNT. This film thickness is 1 order of magnitude smaller than the critical film thickness (about 40 nm) reported by the Derjaguin-Landau-Verwey-Overbeek theory and previous experimental investigations. The stability of the suspended ultrathin water film is attributed to the additional molecular interactions due to the extended water meniscus, which balances the rest of the disjoining pressures.

Introgressive hybridization: brown bears as vectors for polar bear alleles.

Science.gov (United States)

Hailer, Frank

2015-03-01

The dynamics and consequences of introgression can inform about numerous evolutionary processes. Biologists have therefore long been interested in hybridization. One challenge, however, lies in the identification of nonadmixed genotypes that can serve as a baseline for accurate quantification of admixture. In this issue of Molecular Ecology, Cahill et al. (2015) analyse a genomic data set of 28 polar bears, eight brown bears and one American black bear. Polar bear alleles are found to be introgressed into brown bears not only near a previously identified admixture zone on the Alaskan Admiralty, Baranof and Chichagof (ABC) Islands, but also far into the North American mainland. Elegantly contrasting admixture levels at autosomal and X chromosomal markers, Cahill and colleagues infer that male-biased dispersal has spread these introgressed alleles away from the Late Pleistocene contact zone. Compared to a previous study on the ABC Island population in which an Alaskan brown bear served as a putatively admixture-free reference, Cahill et al. (2015) utilize a newly sequenced Swedish brown bear as admixture baseline. This approach reveals that brown bears have been impacted by introgression from polar bears to a larger extent (up to 8.8% of their genome), than previously known, including the bear that had previously served as admixture baseline. No evidence for introgression of brown bear into polar bear is found, which the authors argue could be a consequence of selection. Besides adding new exciting pieces to the puzzle of polar/brown bear evolutionary history, the study by Cahill and colleagues highlights that wildlife genomics is moving from analysing single genomes towards a landscape genomics approach. © 2015 John Wiley & Sons Ltd.

Quantifying the effect of squirt flow dispersion from compliant clay porosity in clay bearing sandstones

DEFF Research Database (Denmark)

Sørensen, Morten Kanne; Fabricius, Ida Lykke

2013-01-01

Compliant porosity in the form of cracks is known to cause significant attenuation and velocity dispersion through pore pressure gradients and consequent relaxation, dubbed squirt flow. Squirt flow from cracks vanish at high confining stress due to crack closing. Studies on clay bearing sandstones......-squirt flow on the bulk modulus of a clay bearing sandstone. The predicted magnitude of the clay-squirt effect on the bulk modulus is compared with experimental data. The clay-squirt effect is found to possibly account for a significant portion of the deviances from Gassmann fluid substitution in claybearing...... sandstones....

Thickness of Residual Wetting Film in Liquid-Liquid Displacement in Capillary Channels

Science.gov (United States)

Beresnev, I. A.; Gaul, W.; Vigil, D.

2010-12-01

Core-annular flow is common in nature, representing, for example, how streams of oil, surrounded by water, move in petroleum reservoirs. Oil, typically a non-wetting fluid, tends to occupy the middle (core) part of a channel, while water forms a surrounding wall-wetting film. What is the thickness of this wetting film? Understanding this question may determine the ultimate oil recovery. A classic theory has been in existence for nearly 50 years offering a solution, although in a controversial manner, for moving gas bubbles. On the other hand, an acceptable, experimentally verified theory for a body of one liquid flowing in another has not been available. We develop a hydrodynamic, testable theory providing an explicit relationship between the thickness of the wetting film and fluid properties for a blob of one fluid moving in another, with neither phase being gas. In its relationship to the capillary number Ca, the thickness of the film is predicted to be proportional to Ca2 at lower Ca and to level off at a constant value of about 20 % the channel radius at higher Ca. The thickness of the film is deduced to be approximately unaffected by the viscosity ratio of the fluids. We have conducted our own laboratory experiments and compiled experimental data from other studies, all of which are mutually consistent and confirm the salient features of the theory. At the same time, the classic law, originally deduced for films surrounding moving gas bubbles but often believed to hold for liquids as well, fails to explain the observations.

Solar advanced internal film receiver; Receptor avanzado de pelicular interna

Energy Technology Data Exchange (ETDEWEB)

Torre Cabezas, M. de la

1990-07-01

In a Solar Central Internal Film Receiver, the heat absorbing fluid (a molten nitrate salt) flows in a thin film down over the non illuminated side of an absorber panel. Since the molten salt working fluid is not contained in complicated tube manifolds, the receiver design is simples than a conventional tube type-receiver resulting in a lower cost and a more reliable receiver. The Internal Film Receiver can be considered as an alternative to the Direct Absorption Receiver, in the event that the current problems of the last one can not be solved. It also describes here the test facility which will be used for its solar test, and the test plans foreseen. (Author) 17 refs.

Improvement of macrophage dysfunction by administration of anti-transforming growth factor-beta antibody in EL4-bearing hosts.

Science.gov (United States)

Maeda, H; Tsuru, S; Shiraishi, A

1994-11-01

An experimental therapy for improvement of macrophage dysfunction caused by transforming growth factor-beta (TGF-beta) was tried in EL4 tumor-bearing mice. TGF-beta was detected in cell-free ascitic fluid from EL4-bearers, but not in that from normal mice, by western blot analysis. The ascites also showed growth-suppressive activity against Mv1Lu cells, and the suppressive activity was potentiated by transient acidification. To investigate whether the functions of peritoneal macrophages were suppressed in EL4-bearers, the abilities to produce nitric oxide and tumor necrosis factor-alpha (TNF-alpha) upon lipopolysaccharide (LPS) stimulation were measured. Both abilities of macrophages in EL4-bearing mice were suppressed remarkably on day 9, and decreased further by day 14, compared with non-tumor-bearing controls. TGF-beta activity was abrogated by administration of anti-TGF-beta antibody to EL4-bearing mice. While a large amount of TGF-beta was detected in ascitic fluid from control EL4-bearers, little TGF-beta was detectable in ascites from EL4-bearers given anti-TGF-beta antibody. Furthermore, while control macrophages exhibited little or no production of nitric oxide and TNF-alpha on LPS stimulation in vitro, macrophages from EL4-bearers administered with anti-TGF-beta antibody showed the same ability as normal macrophages. These results clearly indicate that TGF-beta contributes to macrophage dysfunction and that the administration of specific antibody for TGF-beta reverses macrophage dysfunction in EL4-bearing hosts.

Modelling the evaporation of a tear film over a contact lens.

Science.gov (United States)

Talbott, Kevin; Xu, Amber; Anderson, Daniel M; Seshaiyer, Padmanabhan

2015-06-01

A contact lens (CL) separates the tear film into a pre-lens tear film (PrLTF), the fluid layer between the CL and the outside environment, and a post-lens tear film (PoLTF), the fluid layer between the CL and the cornea. We examine a model for evaporation of a PrLTF on a modern permeable CL allowing fluid transfer between the PrLTF and the PoLTF. Evaporation depletes the PrLTF, and continued evaporation causes depletion of the PoLTF via fluid loss through the CL. Governing equations include Navier-Stokes, heat and Darcy's equations for the fluid flow and heat transfer in the PrLTF and porous layer. The PoLTF is modelled by a fixed pressure condition on the posterior surface of the CL. The original model is simplified using lubrication theory for the PrLTF and CL applied to a sagittal plane through the eye. We obtain a partial differential equation (PDE) for the PrLTF thickness that is first-order in time and fourth-order in space. This model incorporates evaporation, conjoining pressure effects in the PrLTF, capillarity and heat transfer. For a planar film, we find that this PDE can be reduced to an ordinary differential equation (ODE) that can be solved analytically or numerically. This reduced model allows for interpretation of the various system parameters and captures most of the basic physics contained in the model. Comparisons of ODE and PDE models, including estimates for the loss of fluid through the lens due to evaporation, are given. © The Authors 2014. Published by Oxford University Press on behalf of the Institute of Mathematics and its Applications. All rights reserved.

Reducing Friction with a Liquid Film on the Body Surface

Directory of Open Access Journals (Sweden)

Nikolay Klyuev

2018-03-01

Full Text Available A flow of a thin layer of liquid is simulated on a flat surface of a body located in a stream of air. Liquid film on the surface of the body reduces frictional resistance and can be used as a boundary layer control element. The paper presents a mathematical model of the film flow on a half-plane, located at an angle to the horizon. The fluid flow is determined by the force of gravity and friction from the external air current. A model of an incompressible viscous fluid is used in the boundary-layer approximation. The terms of the motion equation are averaged over the film thickness according to the Leibniz rule. In the cross section of the film, a quadratic law is adopted for the distribution of the longitudinal velocity, taking into account friction on the film surface. An analytical solution of the problem is obtained in the form of series in powers of the small parameter for determining the film thickness and the average longitudinal velocity along the length of the plate. It is shown that the friction decreases with flow around a half-plane with a film of liquid on the surface.

X-ray scattering of calcite thin films deposited by atomic layer deposition: Studies in air and in calcite saturated water solution

Energy Technology Data Exchange (ETDEWEB)

Wang, Peng [Lujan Neutron Scattering Center, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States); Hudak, Michael R.; Lerner, Allan [Earth and Environmental Sciences Division, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States); Grubbs, Robert K. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87185 (United States); Wang, Shanmin [Lujan Neutron Scattering Center, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States); Zhang, Zhan; Karapetrova, Evguenia [Advance Photon Source, Argonne National Laboratory, 9700S Cass Ave, Argonne, IL 60439 (United States); Hickmott, Donald [Earth and Environmental Sciences Division, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States); Majewski, Jaroslaw, E-mail: jarek@lanl.gov [Lujan Neutron Scattering Center, Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States)

2014-08-28

Carbonates are one of the most abundant groups of minerals in earth systems and are important in many geological settings and industrial processes. Calcite (CaCO{sub 3}) thin films produced by atomic layer deposition offer a method to evaluate the surficial properties of carbonates as well as interactions at the carbonate–fluid interface. Using synchrotron X-ray reflectivity and X-ray diffraction, these films are observed to be porous, polycrystalline, and have crystallites oriented with the major (104) calcite cleavage plane parallel to the surface of the z-cut single crystal quartz substrate. An Al{sub 2}O{sub 3} buffer layer, present between quartz and the calcite film, does not affect the as-deposited film, but does influence how the films reorganize in contact with fluid. Without a buffer layer, calcite reorients its crystallites to have populations of (006) and (030) parallel to the substrate, while those with an Al{sub 2}O{sub 3} buffer layer become more amorphous. Amorphous films may represent an analog to amorphous calcium carbonate and provide insights into that material's thermophysical behavior. Due to a higher percentage of pore spaces available for fluid infiltration, films deposited at higher temperature make the calcite thin films more susceptible to amorphization. These films are chemically similar, but structurally dissimilar to bulk natural calcite. Nevertheless, they can be a complementary system to traditional single crystal X-ray surface scattering studies on carbonates, particularly for important but less common minerals, to evaluate mineral–fluid interfacial interactions. - Highlights: • Atomic layer deposition (ALD) used to produce calcite films. • Calcite film orientation and crystallinity depend on ALD parameters. • ALD calcite films can be both crystalline and amorphous. • Interaction of water with films can re-orient or amorphize the films. • ALD calcite films may be useful to study carbonate–fluid interfacial

X-ray scattering of calcite thin films deposited by atomic layer deposition: Studies in air and in calcite saturated water solution

International Nuclear Information System (INIS)

Wang, Peng; Hudak, Michael R.; Lerner, Allan; Grubbs, Robert K.; Wang, Shanmin; Zhang, Zhan; Karapetrova, Evguenia; Hickmott, Donald; Majewski, Jaroslaw

2014-01-01

Carbonates are one of the most abundant groups of minerals in earth systems and are important in many geological settings and industrial processes. Calcite (CaCO 3 ) thin films produced by atomic layer deposition offer a method to evaluate the surficial properties of carbonates as well as interactions at the carbonate–fluid interface. Using synchrotron X-ray reflectivity and X-ray diffraction, these films are observed to be porous, polycrystalline, and have crystallites oriented with the major (104) calcite cleavage plane parallel to the surface of the z-cut single crystal quartz substrate. An Al 2 O 3 buffer layer, present between quartz and the calcite film, does not affect the as-deposited film, but does influence how the films reorganize in contact with fluid. Without a buffer layer, calcite reorients its crystallites to have populations of (006) and (030) parallel to the substrate, while those with an Al 2 O 3 buffer layer become more amorphous. Amorphous films may represent an analog to amorphous calcium carbonate and provide insights into that material's thermophysical behavior. Due to a higher percentage of pore spaces available for fluid infiltration, films deposited at higher temperature make the calcite thin films more susceptible to amorphization. These films are chemically similar, but structurally dissimilar to bulk natural calcite. Nevertheless, they can be a complementary system to traditional single crystal X-ray surface scattering studies on carbonates, particularly for important but less common minerals, to evaluate mineral–fluid interfacial interactions. - Highlights: • Atomic layer deposition (ALD) used to produce calcite films. • Calcite film orientation and crystallinity depend on ALD parameters. • ALD calcite films can be both crystalline and amorphous. • Interaction of water with films can re-orient or amorphize the films. • ALD calcite films may be useful to study carbonate–fluid interfacial interactions

Clay squirt: Local flow dispersion in shale-bearing sandstones

DEFF Research Database (Denmark)

Sørensen, Morten Kanne; Fabricius, Ida Lykke

2017-01-01

Dispersion of elastic-wave velocity is common in sandstone and larger in shaly sandstone than in clean sandstone. Dispersion in fluid-saturated shaly sandstone often exceeds the level expected from the stress-dependent elastic moduli of dry sandstone. The large dispersion has been coined clay...... squirt and is proposed to originate from a pressure gradient between the clay microporosity and the effective porosity. We have formulated a simple model that quantifies the clay-squirt effect on bulk moduli of sandstone with homogeneously distributed shale laminae or dispersed shale. The model...... predictions were compared with the literature data. For sandstones with dispersed shale, agreement was found, whereas other sandstones have larger fluid-saturated bulk modulus, possibly due to partially load-bearing shales or heterogeneous shale distribution. The data that agree with the clay-squirt model...

Effect of bicarbonate on biodegradation behaviour of pure magnesium in a simulated body fluid

International Nuclear Information System (INIS)

Li, Zaichun; Song, Guang-Ling; Song, Shizhe

2014-01-01

The effect of bicarbonate on biodegradation of pure magnesium in a simulated body fluid is investigated by means of X-ray diffraction, X-ray photoelectron spectroscopy, polarization curve and electrochemical impedance spectroscopy. The results show that magnesium biodegrades rapidly and non-uniformly during 27 h of immersion in four simulated body fluid solutions containing different concentrations of bicarbonate. The biodegradation rate first decreases and then increases with time. A small amount of bicarbonate in simulated body fluid has an inhibition effect on the Mg dissolution, while an overdose of bicarbonate addition activates the magnesium surface in the simulated body fluid. The interesting phenomena can be interpreted by a surface film model involving precipitation of calcium carbonate and further ionization of bicarbonate in the simulated body fluids, incorporation of calcium, carbonate and phosphate compounds in the surface film, and development of chloride-induced pitting corrosion damage on the magnesium with time

Sources of Matter and Ore-Producing Fluid of the Tamunyer Gold-Sulfide Deposit (Northern Urals): Isotope Results

Science.gov (United States)

Zamyatina, D. A.; Murzin, V. V.

2018-02-01

The Tamunyer deposit is a typical example of gold-sulfide mineralization located in the lower lithologic-stratigraphic unit (S2-D1) of the Auerbach volcanic-plutonic belt. The latter comprises island-arc andesitic volcano-sediments, volcanics, and comagmatic intrusive formations. Carbonates have demonstrated intermediate values of δ13C between marine limestone and mantle. The quartz δ18O is in the range of 15.3-17.2‰. The δ34S of sulfides from the beresitized volcano-sedimentary rocks and ores varies widely from -7.5 to 12‰. The calculated isotope compositions of H2O, CO2, and H2S of the ore-bearing fluid imply two major sources of matter contributing to ore genesis: local rocks and foreign fluid. The ore-bearing fluid was formed by interaction and isotope equilibration between a deep magmatic fluid and marine carbonates (W/R 1), with the contribution of sulfur from the volcano-sedimentary rocks.

Fault diagnosis for tilting-pad journal bearing based on SVD and LMD

Directory of Open Access Journals (Sweden)

Zhang Xiaotao

2016-01-01

Full Text Available Aiming at fault diagnosis for tilting-pad journal bearing with fluid support developed recently, a new method based on singular value decomposition (SVD and local mean decomposition (LMD is proposed. First, the phase space reconstruction of Hankel matrix and SVD method are used as pre-filter process unit to reduce the random noises in the original signal. Then the purified signal is decomposed by LMD into a series of production functions (PFs. Based on PFs, time frequency map and marginal spectrum can be obtained for fault diagnosis. Finally, this method is applied to numerical simulation and practical experiment data. The results show that the proposed method can effectively detect fault features of tilting-pad journal bearing.

Analytical solution of velocity for ammonia-water horizontal falling-film flow

International Nuclear Information System (INIS)

Zhang, Qiang; Gao, Yide

2016-01-01

Highlights: • We built a new falling-film flow model that analyzed the film flow characteristics. • We have obtained a new formula of film thickness over the horizontal tube. • We derived analysis solution to analyze the effect of inertial force to velocity in the entrance region of liquid film. • It described the characters of the ammonia-waterfalling-film film over the horizontal tube. • It is good for falling-film absorption, generation and evaporation to optimizing the design parameters and further improving the capabilities. - Abstract: A new horizontal tube falling film velocity model was built and calculated to analyze the problem of film flow conditions. This model also analyzed the film thickness distribution in horizontal tube falling film flow and considered the effect of the inertial force on velocity. The film thickness and velocity profile can be obtained based on the principle of linear superposition, a method of separation of variables that introduces the effect of variable inertial force on the velocity profile in the process of falling-film absorption. The film flow condition and the film thickness distribution at different fluid Reynolds numbers (Re) and tube diameters were calculated and compared with the results of the Crank–Nicolson numerical solution under the same conditions. The results show that the film flow condition out of a horizontal tube and that the film thickness increases with the fluid Re. At a specific Re and suitable tube diameter, the horizontal tube reaches a more uniform film. Finally, the analysis results have similar trend with the experimental and numerical predicted data in literature.

The Use of Integrated Fluid Inclusion Studies for Constraining Petroleum Charge History at Parsons Pond, Western Newfoundland, Canada

Directory of Open Access Journals (Sweden)

James Conliffe

2017-03-01

Full Text Available This study, based on fluid inclusion petrography, microthermometry and ultraviolet microspectroscopy of inclusion oil, investigates the petroleum charge history at Parsons Pond, western Newfoundland. To address this matter, drill core and cuttings samples of allochthonous and autochthonous strata in the Parson’s Pond area were collected from three exploration wells. Fluid inclusions were examined from fragments of calcite and quartz veins, diagenetic cements in sandstone, and in large hydrothermal dolomite and calcite crystals. Primary aqueous inclusions in authigenic sandstone cements indicate that cementation occurred at relatively shallow depths and low temperatures (<50 °C. Hydrocarbon-bearing fluid inclusions (petroleum, wet gas and gas are generally restricted to calcite and quartz veins, indicating that petroleum and gas migration at Parson’s Pond is fracture-controlled. No hydrocarbons were observed in the diagenetic cements of the essentially tight sandstones. Fluid inclusion microthermometry and ultraviolet microspectroscopy indicate the presence of multiple generations of hydrocarbon fluid, ranging in composition from ~33 API gravity petroleum to pure CH4. Petrographic evidence suggests that hydrocarbons were generated multiple times during progressive burial and heating. In addition, the distribution of hydrocarbon bearing inclusions with depth suggests that deeper levels are gas-prone, with petroleum confined to relatively shallow depths. Although only gas flow was encountered during the drilling of exploration wells at Parson’s Pond, the presence of petroleum-bearing fluid inclusions in calcite and quartz veins indicates that the historical production from shallow wells in the Parsons Pond area likely tapped small reservoirs of fractured petroliferous strata.

Fire prevention film spots for television ... narrator influence on knowledge and attitude changes

Science.gov (United States)

Gene C. Bernardi

1973-01-01

The relative effectiveness of 60-second films on fire prevention, with different narrators, was tested among high school students and by exposure on commercial television channels. The narrators were Smokey Bear, a Youth, and a Ranger. All three films were effective in teaching proper fire use practices to the high school classroom audience. In commercial TV showings,...

Microscale fluid transport using optically controlled marangoni effect

Science.gov (United States)

Thundat, Thomas G [Knoxville, TN; Passian, Ali [Knoxville, TN; Farahi, Rubye H [Oak Ridge, TN

2011-05-10

Low energy light illumination and either a doped semiconductor surface or a surface-plasmon supporting surface are used in combination for manipulating a fluid on the surface in the absence of any applied electric fields or flow channels. Precise control of fluid flow is achieved by applying focused or tightly collimated low energy light to the surface-fluid interface. In the first embodiment, with an appropriate dopant level in the semiconductor substrate, optically excited charge carriers are made to move to the surface when illuminated. In a second embodiment, with a thin-film noble metal surface on a dispersive substrate, optically excited surface plasmons are created for fluid manipulation. This electrode-less optical control of the Marangoni effect provides re-configurable manipulations of fluid flow, thereby paving the way for reprogrammable microfluidic devices.

Geochemistry of U-Th- REE bearing minerals, in radioactive pegmatite in Um Swassi-Dara area, north eastern desert, Egypt

International Nuclear Information System (INIS)

Ali, B. H.

2007-01-01

Some of the pegmatites in the north Eastern Desert of Egypt have high radioactive values, between them the studied radioactive pegmatites which are clustered just in the western margin of Um Swassi-Dara hosted monzogranites. In zoned pegmatite the alteration zones locate between quartz core and intermediate zone are characterizing with the abundance of rare-earth minerals, anderbergite, cenosite, Y-allanite and uranium, thorium minerals such as euxenite, ferro-columbite and complex titanium-yetrum oxides (Kobbite). This zone is a result of many alteration processes developed from volatile-rich magmatic fluids and/or hydrothermal solution which evolved from late differentiated magmatic fluid and lead to increase of U, Th, Zr, Nb, Ti and REE bearing minerals. Such a distinctive alkaline mineralization suite, possibly related to an alkali fluid phase, is superimposed on a more normal, less alkaline group of minerals such as cassiterite, chalcopyrite, and galena. Nb-Ta-Ti minerals bearing U and Th, define a sequence of oxide, cyclosilicate and silicate minerals, showing the effect of hydrothermal overprinting with extreme REE enrichment of the fluids. It can be concluded that the studied mineralization took place in three overlapping stages

Traction and lubricant film temperature as related to the glass transition temperature and solidification. [using infrared spectroscopy on EHD contacts

Science.gov (United States)

Lauer, J. L.; Peterkin, M. E.

1978-01-01

Does a traction fluid have to be a glass or solid under operating conditions. Infrared spectra on dynamic EHD contacts of several types of fluid were used to determine the surface and oil-film temperatures. Polarized spectral runs were made to study molecular alignment. Static glass transition pressures at appropriate temperatures were between 0.1 and 2.0 GPa, with the traction fluid showing the highest. In the EHD contact region, the traction fluid showed both the highest film temperatures as well as the greatest degree of molecular alignment. A plot of the difference between the film and surface temperatures vs shear rate resulted in a master plot valid for all the fluids. From this work, the authors propose a model of 'fluid' traction, where friction between parallel rough molecules provides the traction.

Maximum Recoverable Gas from Hydrate Bearing Sediments by Depressurization

KAUST Repository

Terzariol, Marco

2017-11-13

The estimation of gas production rates from hydrate bearing sediments requires complex numerical simulations. This manuscript presents a set of simple and robust analytical solutions to estimate the maximum depressurization-driven recoverable gas. These limiting-equilibrium solutions are established when the dissociation front reaches steady state conditions and ceases to expand further. Analytical solutions show the relevance of (1) relative permeabilities between the hydrate free sediment, the hydrate bearing sediment, and the aquitard layers, and (2) the extent of depressurization in terms of the fluid pressures at the well, at the phase boundary, and in the far field. Close form solutions for the size of the produced zone allow for expeditious financial analyses; results highlight the need for innovative production strategies in order to make hydrate accumulations an economically-viable energy resource. Horizontal directional drilling and multi-wellpoint seafloor dewatering installations may lead to advantageous production strategies in shallow seafloor reservoirs.

Sex differences in fluid and crystalized intelligence focus on people with psychosis

OpenAIRE

Ćosović Vojislav; Todorović Nevena; Andrić-Petrović Sanja; Marić Nadja P.

2016-01-01

Introduction: Fluid intelligence is described as ability to rapidly solve novel problems and capacity to manage and easily adapt to new situations. Crystallized intelligence reflects ability to timely use lifetime-learned information and skills. Bearing in mind that intelligence is one of the impaired cognitive functions in psychosis, a question arises there are if any sex differences in patients, regarding total IQ, fluid or crystallized intelligence. Aim: To evaluate sex differences in psyc...

EcoBears

DEFF Research Database (Denmark)

Nielsen, Nick; Pedersen, Sandra Bleuenn; Sørensen, Jens Ager

2015-01-01

In this paper, we introduce the EcoBears concept that aims to augment household appliances with functional and aesthetic features to promote their "use'' and "longevity of use'' to prevent their disposal. The EcoBears also aim to support the communication of environmental issues in the home setting....... We present our initial design and implementation of the EcoBears that consist of two bear modules (a mother and her cub). We also present our preliminary concept validations and lessons learned to be considered for future directions....

Capillary waves of compressible fluids

International Nuclear Information System (INIS)

Falk, Kerstin; Mecke, Klaus

2011-01-01

The interplay of thermal noise and molecular forces is responsible for surprising features of liquids on sub-micrometer lengths-in particular at interfaces. Not only does the surface tension depend on the size of an applied distortion and nanoscopic thin liquid films dewet faster than would be expected from hydrodynamics, but also the dispersion relation of capillary waves differ at the nanoscale from the familiar macroscopic behavior. Starting with the stochastic Navier-Stokes equation we study the coupling of capillary waves to acoustic surface waves which is possible in compressible fluids. We find propagating 'acoustic-capillary waves' at nanometer wavelengths where in incompressible fluids capillary waves are overdamped.

Representasi Kriminalitas Dalam Film “Ted” Dan “Ted 2”

OpenAIRE

WIlona, Merrie

2015-01-01

Penelitian ini bertujuan untuk melihat representasi kriminalitas dalam film “Ted” dan “Ted 2”. Bentuk-bentuk tindakan kriminalitas adalah pencurian, penyalahgunaan narkoba, tindakan asusila, pencopetan, penjambretan, penodongan senjata tajam/api, kekerasan fisik, penganiayaan, Perusakan barang orang lain, pembunuhan, penipuan dan korupsi. Film “Ted” dan “Ted 2” dipilih karena menampilkan tokoh utama “Teddy Bear yang identik dengan anak-anak, namun banyak menuai kontroversi. Peneliti ini mengg...

Stable isotopes to detect food-conditioned bears and to evaluate human-bear management

Science.gov (United States)

Hopkins, John B.; Koch, Paul L.; Schwartz, Charles C.; Ferguson, Jake M.; Greenleaf, Schuyler S.; Kalinowski, Steven T.

2012-01-01

We used genetic and stable isotope analysis of hair from free-ranging black bears (Ursus americanus) in Yosemite National Park, California, USA to: 1) identify bears that consume human food, 2) estimate the diets of these bears, and 3) evaluate the Yosemite human–bear management program. Specifically, we analyzed the isotopic composition of hair from bears known a priori to be food-conditioned or non-food-conditioned and used these data to predict whether bears with an unknown management status were food-conditioned (FC) or non-food-conditioned (NFC). We used a stable isotope mixing model to estimate the proportional contribution of natural foods (plants and animals) versus human food in the diets of FC bears. We then used results from both analyses to evaluate proactive (population-level) and reactive (individual-level) human–bear management, and discussed new metrics to evaluate the overall human–bear management program in Yosemite. Our results indicated that 19 out of 145 (13%) unknown bears sampled from 2005 to 2007 were food-conditioned. The proportion of human food in the diets of known FC bears likely declined from 2001–2003 to 2005–2007, suggesting proactive management was successful in reducing the amount of human food available to bears. In contrast, reactive management was not successful in changing the management status of known FC bears to NFC bears, or in reducing the contribution of human food to the diets of FC bears. Nine known FC bears were recaptured on 14 occasions from 2001 to 2007; all bears were classified as FC during subsequent recaptures, and human–bear management did not reduce the amount of human food in the diets of FC bears. Based on our results, we suggest Yosemite continue implementing proactive human–bear management, reevaluate reactive management, and consider removing problem bears (those involved in repeated bear incidents) from the population.

Ammonium in Witwatersrand reefs: a possible indicator of metamorphic fluid flow

International Nuclear Information System (INIS)

Meyer, F.M.

1991-01-01

Ammonium concentrations and NH 4 + /K ratios in the Kimberley Reef indicate chemical interaction with metamorphic fluids. The data, although preliminary, also suggests a gold-ammonium association in that higher gold levels are related to higher NH 4 + /K ratios. Samples from the Ventersdorp Contact Reef are also hydrothermally altered but no ammonium was detected. The low ammonium concentrations suggest that over-printing by NH 4 -bearing metamorphic fluids was negligible. From this it is concluded that chemically different fluid systems must have been operative, probably at different times, during Witwatersrand history. It appears, therefore, that ammonium geochemistry is potentially useful in the study of fluid flow and related gold (re)distribution in Witwatersrand reefs. 17 refs., 2 figs., 1 tab

State Space Formulation of Nonlinear Vibration Responses Collected from a Dynamic Rotor-Bearing System: An Extension of Bearing Diagnostics to Bearing Prognostics.

Science.gov (United States)

Tse, Peter W; Wang, Dong

2017-02-14

Bearings are widely used in various industries to support rotating shafts. Their failures accelerate failures of other adjacent components and may cause unexpected machine breakdowns. In recent years, nonlinear vibration responses collected from a dynamic rotor-bearing system have been widely analyzed for bearing diagnostics. Numerous methods have been proposed to identify different bearing faults. However, these methods are unable to predict the future health conditions of bearings. To extend bearing diagnostics to bearing prognostics, this paper reports the design of a state space formulation of nonlinear vibration responses collected from a dynamic rotor-bearing system in order to intelligently predict bearing remaining useful life (RUL). Firstly, analyses of nonlinear vibration responses were conducted to construct a bearing health indicator (BHI) so as to assess the current bearing health condition. Secondly, a state space model of the BHI was developed to mathematically track the health evolution of the BHI. Thirdly, unscented particle filtering was used to predict bearing RUL. Lastly, a new bearing acceleration life testing setup was designed to collect natural bearing degradation data, which were used to validate the effectiveness of the proposed bearing prognostic method. Results show that the prediction accuracy of the proposed bearing prognostic method is promising and the proposed bearing prognostic method is able to reflect future bearing health conditions.

State Space Formulation of Nonlinear Vibration Responses Collected from a Dynamic Rotor-Bearing System: An Extension of Bearing Diagnostics to Bearing Prognostics

Directory of Open Access Journals (Sweden)

Peter W. Tse

2017-02-01

Full Text Available Bearings are widely used in various industries to support rotating shafts. Their failures accelerate failures of other adjacent components and may cause unexpected machine breakdowns. In recent years, nonlinear vibration responses collected from a dynamic rotor-bearing system have been widely analyzed for bearing diagnostics. Numerous methods have been proposed to identify different bearing faults. However, these methods are unable to predict the future health conditions of bearings. To extend bearing diagnostics to bearing prognostics, this paper reports the design of a state space formulation of nonlinear vibration responses collected from a dynamic rotor-bearing system in order to intelligently predict bearing remaining useful life (RUL. Firstly, analyses of nonlinear vibration responses were conducted to construct a bearing health indicator (BHI so as to assess the current bearing health condition. Secondly, a state space model of the BHI was developed to mathematically track the health evolution of the BHI. Thirdly, unscented particle filtering was used to predict bearing RUL. Lastly, a new bearing acceleration life testing setup was designed to collect natural bearing degradation data, which were used to validate the effectiveness of the proposed bearing prognostic method. Results show that the prediction accuracy of the proposed bearing prognostic method is promising and the proposed bearing prognostic method is able to reflect future bearing health conditions.

Prevalence of antibodies against Brucella spp. in West Greenland polar bears (Ursus maritimus) and East Greenland muskoxen (Ovibos moschatus)

DEFF Research Database (Denmark)

Sonne, Christian; Andersen-Ranberg, Emilie; Rajala, Elisabeth L.

2018-01-01

impact on human health due to consumption of raw meat or otherwise contact with tissues and fluids of infected game species such as muskoxen and polar bears. Here, we present serological results for Baffin Bay polar bears (Ursus maritimus) (n = 96) and North East Greenland muskoxen (Ovibos moschatus) (n...

Thermal Characteristic Analysis and Experimental Study of a Spindle-Bearing System

Directory of Open Access Journals (Sweden)

Li Wu

2016-07-01

Full Text Available In this paper, a thermo-mechanical coupling analysis model of the spindle-bearing system based on Hertz’s contact theory and a point contact non-Newtonian thermal elastohydrodynamic lubrication (EHL theory are developed. In this model, the effect of preload, centrifugal force, the gyroscopic moment, and the lubrication state of the spindle-bearing system are considered. According to the heat transfer theory, the mathematical model for the temperature field of the spindle system is developed and the effect of the spindle cooling system on the spindle temperature distribution is analyzed. The theoretical simulations and the experimental results indicate that the bearing preload has great effect on the frictional heat generation; the cooling fluid has great effect on the heat balance of the spindle system. If a steady-state heat balance between the friction heat generation and the cooling system cannot be reached, thermally-induced preload will lead to a further increase of the frictional heat generation and then cause the thermal failure of the spindle.

FLUID EVOLUTION AND MINERAL REACTIONS DURING SHEAR ZONE FORMATION AT NUSFJORD, LOFOTEN, NORWAY (Invited)

Science.gov (United States)

Kullerud, K.

2009-12-01

At Nusfjord in Lofoten, Norway, three 0.3 - 3 m thick shear zones occur in a gabbro-anorthosite. During deformation, the shear zones were infiltrated by a hydrous fluid enriched in Cl. In the central parts of the shear zones, fluid-rock interaction resulted in complete break-down of the primary mafic silicates. Complete hydration of these minerals to Cl-free amphibole and biotite suggests that the hydrous fluid was present in excess during deformation in these parts of the shear zones. Along the margins of the shear zones, however, the igneous mafic silicates (Cpx, Bt, Opx) were only partly overgrown by hydrous minerals. Here, Cl-enriched minerals (Amph, Bt, Scp, Ap) can be observed. Amphibole shows compositions covering the range 0.1 - 4.0 wt % Cl within single thin sections. Mineral textures and extreme compositional variations of the Cl-bearing minerals indicate large chemical gradients of the fluid phase. Relics of primary mafic silicates and compositionally zoned reaction coronas around primary mafic silicates suggest that the free fluid was totally consumed before the alteration of the primary phases were completed. The extreme variations in the Cl-content of amphibole are inferred to monitor a gradual desiccation of the Cl-bearing grain-boundary fluid during fluid-mineral reactions accordingly: 1) The first amphibole that formed during the reactions principally extracted water from the fluid, resulting in a slight increase in the Cl content of the fluid. 2) Continued amphibole-forming reactions resulted in gradual consumption of the free fluid phase, principally by extracting water from the fluid, resulting in an increase in its Cl-content. Higher Cl-content of the fluid resulted in higher Cl-content of the equilibrium amphibole. 3) The most Cl-enriched amphibole (4 wt % Cl) formed in equilibrium with the last volumes of the grain-boundary fluid, which had evolved to a highly saline solution. Mineral reactions within a 1-2 thick zone of the host rock along

Heat Transfer Analysis of MHD Thin Film Flow of an Unsteady Second Grade Fluid Past a Vertical Oscillating Belt

Science.gov (United States)

Gul, Taza; Islam, Saeed; Shah, Rehan Ali; Khan, Ilyas; Khalid, Asma; Shafie, Sharidan

2014-01-01

This article aims to study the thin film layer flowing on a vertical oscillating belt. The flow is considered to satisfy the constitutive equation of unsteady second grade fluid. The governing equation for velocity and temperature fields with subjected initial and boundary conditions are solved by two analytical techniques namely Adomian Decomposition Method (ADM) and Optimal Homotopy Asymptotic Method (OHAM). The comparisons of ADM and OHAM solutions for velocity and temperature fields are shown numerically and graphically for both the lift and drainage problems. It is found that both these solutions are identical. In order to understand the physical behavior of the embedded parameters such as Stock number, frequency parameter, magnetic parameter, Brinkman number and Prandtl number, the analytical results are plotted graphically and discussed. PMID:25383797

Comparison of Alignment Correction Angles Between Fixed-Bearing and Mobile-Bearing UKA.

Science.gov (United States)

Inoue, Atsuo; Arai, Yuji; Nakagawa, Shuji; Inoue, Hiroaki; Yamazoe, Shoichi; Kubo, Toshikazu

2016-01-01

Good outcomes have been reported with both fixed-bearing and mobile-bearing unicompartmental knee arthroplasty (UKA). However, overcorrected alignment could induce the progression of arthritis on the non-arthroplasty side. Changes of limb alignment after UKA with both types of bearings (fixed bearing: 24 knees, mobile bearing: 28 knees) were investigated. The mean difference between the preoperative standing femoral-tibial angle (FTA) and postoperative standing FTA was significantly larger in mobile bearing UKA group. In fixed-bearing UKA, there must be some laxity in MCL tension so that a 2-mm tension gauge can be inserted. In mobile-bearing UKA, appropriate MCL tension is needed to prevent bearing dislocation. This difference in MCL tension may have caused the difference in the correction angle between the groups. Copyright © 2016 Elsevier Inc. All rights reserved.

Evaporative lithographic patterning of binary colloidal films.

Science.gov (United States)

Harris, Daniel J; Conrad, Jacinta C; Lewis, Jennifer A

2009-12-28

Evaporative lithography offers a promising new route for patterning a broad array of soft materials. In this approach, a mask is placed above a drying film to create regions of free and hindered evaporation, which drive fluid convection and entrained particles to regions of highest evaporative flux. We show that binary colloidal films exhibit remarkable pattern formation when subjected to a periodic evaporative landscape during drying.

An experimental and numerical investigation of flat panel display cell using magnetic fluid

International Nuclear Information System (INIS)

Seo, J.-W.; Jeon, S.-M.; Park, S.J.; Lee, H.-S.

2002-01-01

Optical and fluid dynamical properties of magnetic fluid have been studied experimentally and numerically using a test device with a water-base magnetite magnetic fluid. It has been found that the 3.5 μm thick fluid film absorbs most of the incoming visible light and can be actuated fast enough to realize display devices. The computational simulation shows that the surface tension of the liquid plays the most dominant roles for the test device, and a device that can actuate the magnetic fluid magnetically is proposed

Can numerical simulations accurately predict hydrodynamic instabilities in liquid films?

Science.gov (United States)

Denner, Fabian; Charogiannis, Alexandros; Pradas, Marc; van Wachem, Berend G. M.; Markides, Christos N.; Kalliadasis, Serafim

2014-11-01

Understanding the dynamics of hydrodynamic instabilities in liquid film flows is an active field of research in fluid dynamics and non-linear science in general. Numerical simulations offer a powerful tool to study hydrodynamic instabilities in film flows and can provide deep insights into the underlying physical phenomena. However, the direct comparison of numerical results and experimental results is often hampered by several reasons. For instance, in numerical simulations the interface representation is problematic and the governing equations and boundary conditions may be oversimplified, whereas in experiments it is often difficult to extract accurate information on the fluid and its behavior, e.g. determine the fluid properties when the liquid contains particles for PIV measurements. In this contribution we present the latest results of our on-going, extensive study on hydrodynamic instabilities in liquid film flows, which includes direct numerical simulations, low-dimensional modelling as well as experiments. The major focus is on wave regimes, wave height and wave celerity as a function of Reynolds number and forcing frequency of a falling liquid film. Specific attention is paid to the differences in numerical and experimental results and the reasons for these differences. The authors are grateful to the EPSRC for their financial support (Grant EP/K008595/1).

Dynamic Parameter Identification of Hydrodynamic Bearing-Rotor System

Directory of Open Access Journals (Sweden)

Zhiqiang Song

2015-01-01

Full Text Available A new method called modal parameter genetic time domain identification was employed to study the characteristics of the bearing-rotor system. A multifrequency signal decomposition technology to identify the main components of the measured signal and reject the image mode produced by noise has been used. The first- and second-order natural frequency and damping ratios of the shaft system are identified. Furthermore, because of the deficiency of the traditional least square method, a new genetic identification method to identify the bearing dynamic characteristic parameters has been proposed. The method has been effective albeit with few testing points and operation cases. The derivation of oil-film dynamic coefficients could also provide a basis for shaft system natural vibration characteristic and vibration response analysis. Using the identified dynamic coefficients as the supporting condition, the shaft system modal characteristics were studied. The calculated first- and second-order natural frequencies match quite well those obtained from the modal parameter identification. It was proved that the modal parameter and physical parameter identification methods utilized in this paper are reasonable.

Study on the early surface films formed on Mg-Y molten alloy in different atmospheres

Directory of Open Access Journals (Sweden)

A.R. Mirak

2015-09-01

Full Text Available In the present study, the non-isothermal early stages of surface oxidation of liquid Mg-1%Y alloy during casting were studied under UPH argon, dry air, and air mixed with protective fluorine-bearing gases. The chemistry and morphology of the surface films were characterized by SEM and EDX analyses. The results indicate a layer of smooth and tightly coherent oxidation film composed of MgO and Y2O3 formed on the molten Mg-Y alloy surface with 40–60 nm thickness under dry air. A dendritic/cellular microstructure is clearly visible with Y-rich second phases gathered in surface of the melt and precipitated along the grain/cell boundaries under all gas conditions. Under fluorine-bearing gas mixtures, the surface film was a mixed oxide and fluoride and more even; a flat and folded morphology can be seen under SF6 with oxide as dominated phase and under 1, 1, 1, 2-tetra-fluoroethane, a smooth and compact surface film uniformly covering the inner surface of the bubble with equal oxide and fluoride thickness, which results in a film without any major defects. MgF2 phase appears to be the key characteristic of a good protective film.

Laser-induced vibration of a thin soap film.

Science.gov (United States)

Emile, Olivier; Emile, Janine

2014-09-21

We report on the vibration of a thin soap film based on the optical radiation pressure force. The modulated low power laser induces a counter gravity flow in a vertical free-standing draining film. The thickness of the soap film is then higher in the upper region than in the lower region of the film. Moreover, the lifetime of the film is dramatically increased by a factor of 2. Since the laser beam only acts mechanically on the film interfaces, such a film can be employed in an optofluidic diaphragm pump, the interfaces behaving like a vibrating membrane and the liquid in-between being the fluid to be pumped. Such a pump could then be used in delicate micro-equipment, in chips where temperature variations are detrimental and even in biological systems.

Wire Mesh Dampers for Semi-Floating Ring Bearings in Automotive Turbochargers: Measurements of Structural Stiffness and Damping Parameters

Directory of Open Access Journals (Sweden)

Keun Ryu

2018-04-01

Full Text Available The current work introduces a new semi-floating ring bearing (SFRB system developed for improving the rotordynamic and vibration performance of automotive turbochargers (TCs at extreme operation conditions, such as high temperature, severe external force excitation, and large rotor imbalance. The new bearing design replaces outer oil films, i.e., squeeze film dampers (SFDs, in TC SFRBs with wire mesh dampers (WMDs. This SFRB configuration integrating WMDs aims to implement reliable mechanical components, as an inexpensive and simple alternative to SFDs, with consistent and superior damping capability, as well as predictable forced performance. Since WMDs are in series with the inner oil films of SFRBs, experimentally determined force coefficients of WMDs are of great importance in the design process of TC rotor-bearing systems (RBSs. Presently, the measurements of applied static load and ensuing deflection determine the structural stiffnesses of the WMDs. The WMD damping parameters, including dissipated energy, loss factor, and dry friction coefficient, are estimated from the area of the distinctive local hysteresis loop of the load versus WMD displacement data recorded during consecutive loading-unloading cycles as a function of applied preload with a constant amplitude of motion. The changes in WMD loss factor and dry friction coefficient due to increases in preload are more significant for the WMDs with lower density. The present work shows, to date, the most comprehensive measurements of static load characteristics on the WMDs for application into small automotive TCs. More importantly, the extensive test measurements of WMD deflection versus increasing static loads will aid to anchor predictions of future computation model.

Comparison Between Predictions and Measurements of Performance Characteristics for an Eight Pocket Hybrid (Combination Hydrostatic and Hydrodynamic) Thrust Bearing

Science.gov (United States)

2008-12-03

STB stainless steel housing. Drive End Thrust Collar Free End Splash Guard Slave Thrust Bearing Face STB Flange Figure 12: Exploded view of slave...Bulk Flow Analysis of Hybrid Thrust Bearing for Process Fluid Applications.” ASME Trans., Journal of Tribology , January, Vol. 122 (1), pp. 170-180...ASME Journal of Tribology , Vol. 123, pp. 768-776 [5] San Andrés, L., (2006), “MEEN 626 Notes 2 Derivation of the Classical Reynolds Equation for

Flexible diamond-like carbon film coated on rubber

NARCIS (Netherlands)

Pei, Y.T.; Bui, X.L.; Pal, J.P. van der; Martinez-Martinez, D.; Hosson, J.Th.M. De

2013-01-01

Dynamic rubber seals are major sources of friction of lubrication systems and bearings, which may take up to 70% of the total friction. The solution we present is to coat rubbers with diamond-like carbon (DLC) thin films by which the coefficient of friction is reduced to less than one tenth. Coating

A review of bear farming and bear trade in Lao People's Democratic Republic

Directory of Open Access Journals (Sweden)

E. Livingstone

2018-01-01

Full Text Available This study reviews the bear farming industry in Lao PDR with the objective of documenting the current number of commercial bear facilities (i.e. captive bear facilities judged to be trading in bear bile and/or bears and bear parts and the number of bears contained within these facilities, noting changes since it was last examined between 2000 and 2012 by Livingstone and Shepherd (2014. We surveyed all known commercial bear facilities and searched for previously unrecorded facilities. We compared our records with Livingstone and Shepherd (2014 and corrected some duplicate records from their study. In 2017, we recorded seven commercial facilities; four dedicated bear farms, and three tiger farms that were reportedly also keeping bears. We found that between 2012 and 2017 the recorded number of dedicated bear farms reduced by two, and the recorded number of tiger farms also keeping bears increased by one. Within the same period, the total number of captive bears among all facilities in Lao PDR hardly changed (+one, but the number of bears within each facility did. The northern facilities, owned by ethnic Chinese, have expanded since 2012, and central and southern facilities have downsized or closed. While bear farming appears to be downsizing in Lao PDR overall, efforts to phase it out are undermined by the expansion of foreign owned facilities in the north, within Special and Specific Economic Zones that largely cater to a Chinese market, and where the Lao government's efforts to enforce laws and protect wildlife appear to be lacking. Closing the facilities in the north will require political will and decisive law enforcement. Keywords: Bear farms, Bear bile, Gall bladder, Urso-deoxycholic acid, Bear bile extraction facilities, Lao PDR, Ursus thibetanus

Effects of Gas Rarefaction on Dynamic Characteristics of Micro Spiral-Grooved Thrust Bearing.

Science.gov (United States)

Liu, Ren; Wang, Xiao-Li; Zhang, Xiao-Qing

2012-04-01

The effects of gas-rarefaction on dynamic characteristics of micro spiral-grooved-thrust-bearing are studied. The Reynolds equation is modified by the first order slip model, and the corresponding perturbation equations are then obtained on the basis of the linear small perturbation method. In the converted spiral-curve-coordinates system, the finite-volume-method (FVM) is employed to discrete the surface domain of micro bearing. The results show, compared with the continuum-flow model, that under the slip-flow regime, the decrease in the pressure and stiffness become obvious with the increasing of the compressibility number. Moreover, with the decrease of the relative gas-film-thickness, the deviations of dynamic coefficients between slip-flow-model and continuum-flow-model are increasing.

The determination of the pressure-viscosity coefficient of a lubricant through an accurate film thickness formula and accurate film thickness measurements : part 2 : high L values

NARCIS (Netherlands)

Leeuwen, van H.J.

2011-01-01

The pressure-viscosity coefficient of a traction fluid is determined by fitting calculation results on accurate film thickness measurements, obtained at different speeds, loads, and temperatures. Through experiments, covering a range of 5.6 film thickness values are

Molecular phylogeny and SNP variation of polar bears (Ursus maritimus), brown bears (U. arctos), and black bears (U. americanus) derived from genome sequences.

Science.gov (United States)

Cronin, Matthew A; Rincon, Gonzalo; Meredith, Robert W; MacNeil, Michael D; Islas-Trejo, Alma; Cánovas, Angela; Medrano, Juan F

2014-01-01

We assessed the relationships of polar bears (Ursus maritimus), brown bears (U. arctos), and black bears (U. americanus) with high throughput genomic sequencing data with an average coverage of 25× for each species. A total of 1.4 billion 100-bp paired-end reads were assembled using the polar bear and annotated giant panda (Ailuropoda melanoleuca) genome sequences as references. We identified 13.8 million single nucleotide polymorphisms (SNP) in the 3 species aligned to the polar bear genome. These data indicate that polar bears and brown bears share more SNP with each other than either does with black bears. Concatenation and coalescence-based analysis of consensus sequences of approximately 1 million base pairs of ultraconserved elements in the nuclear genome resulted in a phylogeny with black bears as the sister group to brown and polar bears, and all brown bears are in a separate clade from polar bears. Genotypes for 162 SNP loci of 336 bears from Alaska and Montana showed that the species are genetically differentiated and there is geographic population structure of brown and black bears but not polar bears.

Skating on a Film of Air: Drops Impacting on a Surface

Science.gov (United States)

Kolinski, John M.; Rubinstein, Shmuel M.; Mandre, Shreyas; Brenner, Michael P.; Weitz, David A.; Mahadevan, L.

2012-02-01

The commonly accepted description of drops impacting on a surface typically ignores the essential role of the air that is trapped between the impacting drop and the surface. Here we describe a new imaging modality that is sensitive to the behavior right at the surface. We show that a very thin film of air, only a few tens of nanometers thick, remains trapped between the falling drop and the surface as the drop spreads. The thin film of air serves to lubricate the drop enabling the fluid to skate on the air film laterally outward at surprisingly high velocities, consistent with theoretical predictions. Eventually this thin film of air breaks down as the fluid wets the surface via a spinodal-like mechanism. Our results show that the dynamics of impacting drops are much more complex than previously thought, with a rich array of unexpected phenomena that require rethinking classic paradigms.

Use of an electric field in an electrostatic liquid film radiator.

Science.gov (United States)

Bankoff, S G; Griffing, E M; Schluter, R A

2002-10-01

Experimental and numerical work was performed to further the understanding of an electrostatic liquid film radiator (ELFR) that was originally proposed by Kim et al.(1) The ELFR design utilizes an electric field that exerts a normal force on the interface of a flowing film. The field lowers the pressure under the film in a space radiator and, thereby, prevents leakage through a puncture in the radiator wall. The flowing film is subject to the Taylor cone instability, whereby a cone of fluid forms underneath an electrode and sharpens until a jet of fluid is pulled toward the electrode and disintegrates into droplets. The critical potential for the instability is shown to be as much as an order of magnitude higher than that used in previous designs.(2) Furthermore, leak stoppage experiments indicate that the critical field is adequate to stop leaks in a working radiator.