Thermohydrodynamic Behavior of a Slider Pocket Bearing

2005 ◽  
Vol 128 (2) ◽  
pp. 312-318 ◽  
Author(s):  
Mihai B. Dobrica ◽  
Michel Fillon
Keyword(s):  
Pressure Distribution ◽  
Reverse Flow ◽  
Three Dimensional ◽  
Convective Boundary ◽  
Inertia Effects ◽  
Good Convergence ◽  
Bearing Design ◽  
The One ◽  
Volume Method ◽  
Generalized Reynolds Equation

Pocket-pads or steps are often used in journal bearing design, allowing improvement of the latter’s dynamic behavior. Similar “discontinuous” geometries are used in designing thrust bearing pads. A literature review shows that, to date, only isoviscous and adiabatic studies of such geometries have been performed. The present paper addresses this gap, proposing a complete thermohydrodynamic (THD) steady model, adapted to three-dimensional (3D) discontinuous geometries. The model is applied to the well-known geometry of a slider pocket bearing, operating with an incompressible viscous lubricant. A model based on the generalized Reynolds equation, with concentrated inertia effects, is used to determine the 2D pressure distribution. On this basis, a 3D field of velocities is constructed which, in turn, allows the resolution of the 3D energy equation. Using a variable-size grid improves the accuracy in the discontinuity region, allowing an evaluation of the magnitude of error induced by Reynolds assumptions. The equations are solved using the finite volume method. This ensures good convergence even when a significant reverse flow is present. Heat evacuation through the pad is taken into account by solving the Laplace equation with convective boundary conditions that are realistic. The runner’s temperature, assumed constant, is determined by imposing a zero value for the global heat flux balance. The constructed model gives the pressure distribution and velocity fields in the fluid, as well as the temperature distribution across the fluid and solid pad. Results show important transversal temperature gradients in the fluid, especially in the areas of minimal film thickness. This further justifies the use of a complete THD model such as the one employed.

Heat and Mass Diffusion Including Shrinkage and Hygrothermal Stress during Drying of Holed Ceramics Bricks

2011 ◽  
Vol 312-315 ◽  
pp. 971-976 ◽  
Author(s):  
J. Barbosa da Silva ◽  
G. Silva Almeida ◽  
W.C.P. Barbosa de Lima ◽  
Gelmires Araújo Neves ◽  
Antônio Gilson Barbosa de Lima
Keyword(s):  
Moisture Content ◽  
Three Dimensional ◽  
Average Moisture Content ◽  
Stress Distributions ◽  
Drying Process ◽  
Convective Boundary ◽  
Volume Method ◽  
Hygrothermal Stress ◽  
Thermo Physical Properties ◽  
Good Agreement

The Aim of this Work Is to Present a Three-Dimensional Mathematical Modelling to Predict Heat and Mass Transport inside the Industrial Brick with Rectangular Holes during the Drying Including Shrinkage and Hygrothermalelastic Stress Analysis. the Numerical Solution of the Diffusion Equation, Being Used the Finite-Volume Method, Considering Constant Thermo-Physical Properties and Convective Boundary Conditions at the Surface of the Solid, it Is Presented and Analyzed. Results of the Temperature, Moisture Content and Stress Distributions, and Drying and Heating Kinetics Are Shown and Analyzed. Results of the Average Moisture Content and Surface Temperature of the Brick along the Drying Process Are Compared with Experimental Data (T = 80.0oC and RH = 4.6 %) and Good Agreement Was Obtained. it Was Verified that the Largest Temperature, Moisture Content and Stress Gradients Are Located in the Intern and External Vertexes of the Brick.

scholarly journals ANALYSIS OF THE NUMERICAL MODELLING OF TURBULENCE IN THE CONICAL REVERSE-FLOW CYCLONE

2010 ◽  
Vol 2 (5) ◽  
pp. 17-22
Author(s):  
Inga Jakštonienė ◽  
Petras Vaitiekūnas
Keyword(s):  
Fluid Flow ◽  
Numerical Modelling ◽  
Reverse Flow ◽  
Three Dimensional ◽  
Cylindrical Part ◽  
Solid Particles ◽  
Good Prediction ◽  
Transfer Equations ◽  
Volume Method ◽  
Tangential Inlet

The paper describes the numerical modelling of the swirling fluid flow in the Stairmand cyclone (conical reverse-flow – CRF) with tangential inlet (equipment for separating solid particles from the gaseous fluid flow). A review of experimental and theoretical papers is conducted introducing three-dimen­sional differential equations for transfer processes. The numerical modelling of the Stairmand cyclone the height of which is 0.75 m, diameter – 0.17 m, the height of a cylindrical part – 0.290 m, a conical part – 0,39 m and an inlet area is 0,085×0,032 m is presented. When governing three-dimensional fluid flow, transfer equations Navje-Stokes and Reynolds are solved using the finite volume method in a body-fitted co-ordinate system using standard k– e and RNG k– e model of turbulence. Modelling is realised for inlet velocity 4.64, 9.0 and 14.8 m/s (flow rate was 0.0112, 0.0245 and 0.0388 m3/s). The results obtained from the numerical tests have demonstrated that the RNG k– e model of turbulence yields a reasonably good prediction for highly swirling flows in cyclones: the presented numerical results (tangential and radial velocity profiles) are compared with numerical and experimental data obtained by other authors. The mean relative error of ± 7,5% is found.

Numerical Analysis of Blast Load from Explosive Materials Using Finite Volume Method

2016 ◽  
Vol 723 ◽  
pp. 789-794 ◽  
Author(s):  
Michał Lidner ◽  
Zbigniew Szcześniak
Keyword(s):  
Shock Wave ◽  
Numerical Analysis ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Three Dimensional ◽  
One Dimensional ◽  
Good Convergence ◽  
Explosive Materials ◽  
Impulse Pressure ◽  
Volume Method

A method of numerical analysis of the phenomenon of the air shock wave propagation is presented. The paper describes an explicit own solution. It uses Finite Volume Method (FVM). It also takes into account energy losses due to a heat transfer. For validation, the results of numerical analysis were compared with the literature reports. Both one-dimensional (an explosion in the pipe) and three-dimensional (explosion within the compartment) flow of a shock wave were analysed. Values of impulse, pressure, and its duration were studied. Finally, an overall good convergence of numerical results with experiments was achieved. Also the most important parameters were well reflected.

Transonic and Supersonic Inviscid Flow Equations in 3-D Eccentric Nozzles

2002 ◽  
Author(s):  
Ali Reza Mazaheri ◽  
Homayoon Emdad ◽  
Goodarz Ahmadi
Keyword(s):  
Three Dimensional ◽  
Flow Simulation ◽  
Inviscid Flow ◽  
Analytic Solutions ◽  
Inviscid Flows ◽  
Flow Equations ◽  
The Stability ◽  
The One ◽  
Volume Method ◽  
Steady And Unsteady Flows

Three dimensional unsteady inviscid flows in convergent-divergent nozzles is of importance in understanding the stability of rockets and jet propulsion. A computer program for evaluating unsteady inviscid flow conditions in three-dimensional eccentric as well as concentric nozzles is developed. The program uses the cell-centered finite-volume method based on Roe’s approximate Riemann solver scheme. The flow simulation results in concentric circular nozzles are compared with the one-dimensional analytic solutions and the accuracy of the computation model is verified. The results for steady and unsteady flows through eccentric and concentric convergent-divergent nozzles are then presented. A range of exit to throat areas, pressure ratios, and inlet Mach number are considered.

Flow Analysis on Hydrostatic Guideway of Precision CNC Lathe Based on FLUENT

2011 ◽  
Vol 52-54 ◽  
pp. 970-973
Author(s):  
Song Li ◽  
Jin Chun Song ◽  
Ming Li Han ◽  
Yu Jie Ren
Keyword(s):  
Pressure Distribution ◽  
Fluid Velocity ◽  
Flow Analysis ◽  
Fluid Motion ◽  
Three Dimensional ◽  
Machining Accuracy ◽  
Three Dimensional Model ◽  
Cnc Lathe ◽  
Flow Pressure ◽  
Volume Method

In order to improve the machining accuracy of precision CNC lathe, and explore the fluid motion law in the closed hydrostatic guideway, three-dimensional model of hydrostatic oil chamber was established using preprocessor GAMBIT of FLUENT. The Finite Volume Method of Fluent has been used to the simulation of fluid three-dimensional velocity field and pressure field. The fluid velocity vector and pressure distribution graphs are obtained. They reveal the flow field law in the gap fluid. The simulation result of the pressure distribution shows that the flow pressure was not changing in linear gradient all around the gap under moving condition.

Study on Characteristics of DVT500 Feedback Hydrostatic Thrust Bearing

2013 ◽  
Vol 589-590 ◽  
pp. 717-722
Author(s):  
Dong Sheng Li ◽  
Xi Bing Li ◽  
Jian Jia Wang ◽  
Xun Wang ◽  
Yun Shi Ma ◽  
...  
Keyword(s):  
Thrust Bearing ◽  
Three Dimensional ◽  
Processing Efficiency ◽  
Computational Fluid Dynamics Cfd ◽  
Bearing Design ◽  
Motion Characteristics ◽  
Volume Method ◽  
Bearing Structure ◽  
Main Factor ◽  
Lubricating Properties

With the increase of the weight and volume of the processed parts, large CNC vertical lathe has become the ideal equipment for large parts. The main factor that influences the processing efficiency of CNC vertical lathe is hydrostatic thrust bearing speed. The thrust ball bearing with DVT500 CNC vertical lathe was adapted as the research object to research on motion characteristics of CNC vertical lathe hydrostatic thrust bearing, and the three-dimensional flow mathematical model and boundary condition of hydrostatic thrust bearing system were built up. Then the hydrostatic thrust bearing temperature field distribution and lubricating properties were obtained with the use of computational fluid dynamics (CFD) theory and the finite volume method combined with the segregated solver of FLUENT. The simulation results show that, using oil feedback can improve the bearing capacity and stability of thrust bearing, structure of large hydrostatic thrust bearing design and has a guiding significance to the operation reliability.

Diffraction contrast of dislocations in icosahedral quasicrystals

1990 ◽  
Vol 48 (4) ◽  
pp. 454-455
Author(s):  
K. Urban ◽  
Z. Zhang ◽  
M. Wollgarten ◽  
D. Gratias
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Complete Characterization ◽  
Extinction Condition ◽  
Burgers Vector ◽  
Diffraction Contrast ◽  
Lattice Geometry ◽  
Reference Space ◽  
Icosahedral Quasicrystals ◽  
The One

Recently dislocations have been observed by electron microscopy in the icosahedral quasicrystalline (IQ) phase of Al65Cu20Fe15. These dislocations exhibit diffraction contrast similar to that known for dislocations in conventional crystals. The contrast becomes extinct for certain diffraction vectors g. In the following the basis of electron diffraction contrast of dislocations in the IQ phase is described. Taking account of the six-dimensional nature of the Burgers vector a “strong” and a “weak” extinction condition are found.Dislocations in quasicrystals canot be described on the basis of simple shear or insertion of a lattice plane only. In order to achieve a complete characterization of these dislocations it is advantageous to make use of the one to one correspondence of the lattice geometry in our three-dimensional space (R3) and that in the six-dimensional reference space (R6) where full periodicity is recovered . Therefore the contrast extinction condition has to be written as gpbp + gobo = 0 (1). The diffraction vector g and the Burgers vector b decompose into two vectors gp, bp and go, bo in, respectively, the physical and the orthogonal three-dimensional sub-spaces of R6.

Exploring the Multidimensional Facets of Authoritarianism: Authoritarian Aggression and Social Dominance Orientation

2008 ◽  
Vol 67 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Stefano Passini
Keyword(s):  
Social Dominance ◽  
Factor Model ◽  
Three Dimensional ◽  
Social Dominance Orientation ◽  
Model Fit ◽  
Regression Analyses ◽  
One Dimensional ◽  
Confirmatory Factor ◽  
The One ◽  
Better Than

The relation between authoritarianism and social dominance orientation was analyzed, with authoritarianism measured using a three-dimensional scale. The implicit multidimensional structure (authoritarian submission, conventionalism, authoritarian aggression) of Altemeyer’s (1981, 1988) conceptualization of authoritarianism is inconsistent with its one-dimensional methodological operationalization. The dimensionality of authoritarianism was investigated using confirmatory factor analysis in a sample of 713 university students. As hypothesized, the three-factor model fit the data significantly better than the one-factor model. Regression analyses revealed that only authoritarian aggression was related to social dominance orientation. That is, only intolerance of deviance was related to high social dominance, whereas submissiveness was not.

Sea Urchins and Circuses: The Modernist Natural Histories of Jean Painlevé and Alexander Calder

2018 ◽  
Vol 13 (2) ◽  
pp. 187-211
Author(s):  
Patricia E. Chu
Keyword(s):  
New Media ◽  
Sea Urchins ◽  
Life Sciences ◽  
Three Dimensional ◽  
Machine Age ◽  
Avant Garde ◽  
History Of ◽  
And Performance ◽  
The One ◽  
Natural Historian

The Paris avant-garde milieu from which both Cirque Calder/Calder's Circus and Painlevé’s early films emerged was a cultural intersection of art and the twentieth-century life sciences. In turning to the style of current scientific journals, the Paris surrealists can be understood as engaging the (life) sciences not simply as a provider of normative categories of materiality to be dismissed, but as a companion in apprehending the “reality” of a world beneath the surface just as real as the one visible to the naked eye. I will focus in this essay on two modernist practices in new media in the context of the history of the life sciences: Jean Painlevé’s (1902–1989) science films and Alexander Calder's (1898–1976) work in three-dimensional moving art and performance—the Circus. In analyzing Painlevé’s work, I discuss it as exemplary of a moment when life sciences and avant-garde technical methods and philosophies created each other rather than being classified as separate categories of epistemological work. In moving from Painlevé’s films to Alexander Calder's Circus, Painlevé’s cinematography remains at the forefront; I use his film of one of Calder's performances of the Circus, a collaboration the men had taken two decades to complete. Painlevé’s depiction allows us to see the elements of Calder's work that mark it as akin to Painlevé’s own interest in a modern experimental organicism as central to the so-called machine-age. Calder's work can be understood as similarly developing an avant-garde practice along the line between the bestiary of the natural historian and the bestiary of the modern life scientist.

Sign in / Sign up

Export Citation Format

Share Document