A Theoretical Investigation of Pressure Depression in Externally Pressurized Gas-Lubricated Circular Thrust Bearings

1961 ◽  
Vol 83 (2) ◽  
pp. 201-208 ◽  
Author(s):  
Haruo Mori
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Shock Wave ◽  
Qualitative Agreement ◽  
Load Capacity ◽  
Pressure Profile ◽  
Theoretical Explanation ◽  
Good Qualitative Agreement ◽  
Thrust Bearings ◽  
Approximate Mathematical Model

A theoretical explanation of the experimentally observed depression of the pressure profile in externally pressurized gas-lubricated circular thrust bearings is presented, based on a concept new to gas lubrication, that of the generation of a shock wave in the bearing clearance space. On the basis of an approximate mathematical model, the bearing pressure distribution and load capacity are determined, and the effects of several bearing parameters are discussed. Good qualitative agreement is found between the analytical results and available experimental data.

Modeling of Martensite Accommodation Effect on Mechanical Behavior of Shape Memory Alloys

1999 ◽  
Vol 121 (1) ◽  
pp. 102-104 ◽  
Author(s):  
M. E. Evard ◽  
A. E. Volkov
Keyword(s):  
Experimental Data ◽  
Plastic Deformation ◽  
Shape Memory Alloys ◽  
Mechanical Behavior ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Qualitative Agreement ◽  
Strain Accumulation ◽  
Good Qualitative Agreement

An approach has been presented to account for micro-plastic deformation and stress produced by accommodation of martensite. This has made it possible to describe such phenomena as incomplete recovery of strain, strain accumulation at thermocycling, and repeated two-way shape memory effect. Results of modeling are in good qualitative agreement with experimental data.

scholarly journals Measurement and prediction of binary mixture flash point

2013 ◽  
Vol 11 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Mariana Hristova
Keyword(s):  
Experimental Data ◽  
Binary Mixture ◽  
Binary Mixtures ◽  
Qualitative Agreement ◽  
Flash Point ◽  
Wilson Equation ◽  
Good Qualitative Agreement ◽  
Raoult’S Law ◽  
Raoult's Law

AbstractThe flash points of three binary mixtures, containing n-heptane, o-xylene, m-xylene and ethylbenzene, were measured by Pensky-Martens closed cup tester. The experimental data were compared with the calculated values using Liaw’s Model with the application of Raoult’s Law and Wilson equation. These equations were in good qualitative agreement.

Exploring Theories of Victimization Using a Mathematical Model of Burglary

2011 ◽  
Vol 48 (1) ◽  
pp. 83-109 ◽  
Author(s):  
Ashley B. Pitcher ◽  
Shane D. Johnson
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Qualitative Agreement ◽  
The Other ◽  
Residential Burglary ◽  
Foraging Activity ◽  
Good Qualitative Agreement ◽  
Agent Based ◽  
Stable Variation ◽  
Near Repeat

Research concerned with burglary indicates that it is clustered not only at places but also in time. Some homes are victimized repeatedly, and the risk to neighbors of victimized homes is temporarily elevated. The latter type of burglary is referred to as a near repeat. Two theories have been proposed to explain observed patterns. The boost hypothesis states that risk is elevated following an event reflecting offender foraging activity. The flag hypothesis, on the other hand, suggests that time-stable variation in risk provides an explanation where data for populations with different risks are analyzed in the aggregate. To examine this, the authors specify a series of discrete mathematical models of urban residential burglary and examine their outcomes using stochastic agent-based simulations. Results suggest that variation in risk alone cannot explain patterns of exact and near repeats, but that models which also include a boost component show good qualitative agreement with published findings.

On the Thermomagnetic Gas Torque for Collinear Static and Alternating Magnetic Fields

1970 ◽  
Vol 25 (10) ◽  
pp. 1367-1369
Author(s):  
S. Hess ◽  
L. Waldmann
Keyword(s):  
Experimental Data ◽  
Magnetic Fields ◽  
Kinetic Theory ◽  
Qualitative Agreement ◽  
Quantitative Agreement ◽  
Good Qualitative Agreement ◽  
Thermal Pressure ◽  
Alternating Magnetic Fields

Abstract Results obtained within the framework of kinetic theory are presented for the part of the thermo-magnetic gas torque which stems from the thermal pressure and is associated with the influence of the magnetic fields on the viscosity (Senftleben-Beenakker effect). Good qualitative agreement and a quantitative agreement within a factor of roughly 1.5 are found between the theory and the experimental data of Smith and Scott [1969].

Some Properties of Compressional Waves in Lennard-Jones and Devonshire Liquids. II. Shock Waves

1961 ◽  
Vol 14 (3) ◽  
pp. 372 ◽  
Author(s):  
HG David ◽  
SD Hamann
Keyword(s):  
Shock Wave ◽  
Equation Of State ◽  
Shock Waves ◽  
Qualitative Agreement ◽  
Theoretical Calculations ◽  
Condensed Substance ◽  
Adiabatic Expansion ◽  
Good Qualitative Agreement ◽  
Compressional Waves ◽  
Lennard Jones

This paper describes some theoretical calculations of the thermodynamic changes which occur when a condensed substance is compressed by a shock wave from an explosion. It is assumed that the material is a simple molecular fluid (or a plastic solid) obeying Lennard-Jones and Devonshire's equation of state. The calculations have been applied to single and colliding shock waves, to shocks generated in a precompressed material, and to the adiabatic expansion of a material from a shocked state. The results are in good qualitative agreement with the experi- mental data where these exist. In addition they suggest possible ways of extending the scope and usefulness of shock wave experiments.

Design Optimization of Gas Foil Thrust Bearings for Maximum Load Capacity

2015 ◽  
Author(s):  
Tae Ho Kim ◽  
Tae Won Lee
Keyword(s):  
Experimental Data ◽  
Film Thickness ◽  
Load Capacity ◽  
Maximum Load ◽  
Drag Torque ◽  
Rotor Speed ◽  
Design Guideline ◽  
Film Pressure ◽  
Thrust Bearings ◽  
Minimum Film Thickness

Improvement of the load capacity of gas foil thrust bearings (GFTBs) is important to broadening their application in oil-free microturbomachinery (<250 kW) with high power density. Although GFTBs have the significant advantage of low friction without the use of lubrication systems compared to oil film thrust bearings, their inherently low load capacity has limited their application. The aim of the present study was to develop a design guideline for increasing the load capacity of GFTBs. The Reynolds equation for an isothermal isoviscous ideal gas was used to calculate the gas film pressure. To predict the ultimate load capacity of the GFTB, the pressure was averaged in the radial direction of the gas flow field used to deflect the foil structure. The load capacity, film pressure profile, and film thickness profile were predicted for a GFTB with an outer radius of 55 mm, inner radius of 30 mm, and eight foils each of arc length 45°. The predictions showed that the load capacity of the GFTB increased with increasing rotor speed and decreasing minimum film thickness, and was always lower than the analytically determined limit value for infinite rotor speed (obtained by simple algebraic equations). A parametric study in which the ramp extent (or inclined angle) was increased from 5° to 40°, and the ramp height from 0 to 0.320 mm, revealed that the GFTB had an optimal ramp extent of ∼22.5° and ramp height of ∼0.030 mm for maximum load capacity. Interestingly, the optimal values were also valid for a rigid-surface bearing. The predicted load capacities for a ramp extent of ∼22.5° and increasing ramp height from 0.030 to 0.320 mm were compared with experimental data obtained from a previous work. The predictions for a ramp height of 0.155 mm were in good agreement with the experimental data for all three test GFTBs with outer radii of 45, 50, and 55 mm, respectively. In addition, this paper shows that the predicted drag torque increases linearly with increasing rotor speed and decreasing minimum film thickness, and nonlinearly with decreasing ramp height. The drag torque significantly increased only for ramp heights below the optimal value. The predictions imply that the optimal ramp height improves the load capacity of the GFTB with little change in the drag torque.

Experimental Study of Shock Wave / Turbulent Boundary Layer Interaction

2010 ◽  
Vol 5 (2) ◽  
pp. 8-16
Author(s):  
Anton S. Vereshchagin ◽  
Vitaliy N. Zinoviev ◽  
Alexey Yu. Pak ◽  
Ivan V. Kazanin ◽  
Anna F. Fomina ◽  
...  
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Mathematical Model ◽  
Shock Wave ◽  
Experimental Study ◽  
Turbulent Boundary Layer ◽  
Theoretical Investigation ◽  
Solid Particles ◽  
Nonlinear Filtration ◽  
Boundary Layer Interaction

The experimental and theoretical investigation of the process of helium permeation by hollow permeable solid particles (microspheres) was done. Mathematical model of this process was derived using the assumption of instant diffusion and nonlinear filtration law of gas through a particle shell. The comparison of experimental data and simulation of the process was made, the characteristic times of the process of helium permeation by microspheres were obtained.

Theoretical Flow-Models for Externally Pressurized Gas Bearings

1969 ◽  
Vol 91 (1) ◽  
pp. 181-193 ◽  
Author(s):  
H. Mori ◽  
Y. Miyamatsu
Keyword(s):  
Shock Wave ◽  
Load Capacity ◽  
Operating Conditions ◽  
Gas Bearings ◽  
Flow Models ◽  
Thrust Bearings ◽  
Pressure Distributions ◽  
In Series ◽  
Pressure Changes ◽  
Wide Operating

In order to make clear the characteristics of externally pressurized gas bearings, several mathematical flow-models are constructed by making proper chains of fundamental and elemental flow-patterns and pressure changes for circular thrust bearings with single central supply hole. The suggested flow-models, which are the combination of rather simple elements to make the mathematical analysis easy, are quite effective to explain the pressure distributions, the load capacity, and the rate of flow observed experimentally over wide operating conditions. And also, these flow-models make it possible to understand the effects of the inherent compensation, the so-called restrictions in series and the occurrence of shock wave.

scholarly journals Monte Carlo Calculation of Fragment Distributions in Nuclear Reactions

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
A. Deppman ◽  
E. Andrade-II ◽  
P. C. R. Rossi ◽  
F. Garcia ◽  
J. R. Maiorino
Keyword(s):  
Experimental Data ◽  
Monte Carlo ◽  
Qualitative Agreement ◽  
Nuclear Reactions ◽  
Monte Carlo Calculation ◽  
High Energy ◽  
Fission Reactions ◽  
Good Qualitative Agreement ◽  
Driven Systems ◽  
Mc Method

The fragments produced in nuclear reactions for accelarator driven systems (ADS) operation form elements that can have effects on the structure of the reactor. In this regard, the calculation of fragment distributions gives important information for the development of ADS. To obtain those distributions, the Monte Carlo (MC) method is an important tool, and in this work we describe calculations of fragment distributions through a MC code for reactions initiated by intermediate- and high-energy protons and photons on actinide and preactinide nuclei. We study the production of fragments through spallation and fission reactions. The results show good qualitative agreement with experimental data.

scholarly journals Advancing drops on curved and flat surfaces

2019 ◽  
Vol 11 (4) ◽  
pp. 223-226
Author(s):  
Claudiu PATRASCU ◽  
Ioana RASUCEANU ◽  
Corneliu BALAN
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Qualitative Agreement ◽  
Immiscible Liquid ◽  
Solid Surfaces ◽  
Good Qualitative Agreement ◽  
Hydrophobic Surfaces ◽  
Flat Surfaces ◽  
Theoretical Predictions ◽  
Inclined Planes

The paper is concerned with the dynamics of advancing liquid blobs of fluid on curved and flat solid surfaces, such as cycloids and inclined planes. We investigate the kinematics of such blobs on hydrophobic surfaces with emphasis on the shape of the interface as the fluid advances. A theoretical model is proposed that captures the shape of the interface at early times. Also, the trajectory of the fluid, as it detaches from the cycloid, is investigated and compared with theoretical predictions. We find a good qualitative agreement between predictions and experimental data. As an extension of the present findings, we also investigate the shape and the dynamics of advancing drops on cycloids, placed in a viscous outer immiscible liquid. We find both similarities, in terms of kinematics, and specific differences in the shape of the advancing drop.

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