scholarly journals Pulsating Gas Flow In Pipes Part I -- Damping Coefficients

1961 ◽  
Author(s):  
A.O. Converse ◽  
R.L. Pigford
Keyword(s):  
Gas Flow ◽  
Damping Coefficients ◽  
Pulsating Gas Flow

Numerical investigation of the effect of a recess on the characteristics of a pulsating gas flow

1998 ◽  
Vol 71 (3) ◽  
pp. 474-480
Author(s):  
A. N. Antonov ◽  
M. A. Antonov ◽  
I. A. Graur ◽  
L. V. Kosarev ◽  
B. N. Chetverushkin
Keyword(s):  
Numerical Investigation ◽  
Gas Flow ◽  
Pulsating Gas Flow

scholarly journals Thermo-Elasto-Hydrodynamic Characteristics Analysis of Journal Microbearing Lubricated with Rarefied Gas

Micromachines ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 955
Author(s):  
Yao Wu ◽  
Lihua Yang ◽  
Tengfei Xu ◽  
Wei Wu
Keyword(s):  
High Speed ◽  
Gas Flow ◽  
Rarefied Gas ◽  
Load Capacity ◽  
Hydrodynamic Characteristics ◽  
Small Scale ◽  
Damping Coefficients ◽  
Stiffness Coefficients ◽  
Characteristics Analysis ◽  
Lubrication Characteristics

Temperature rise and elastic deformation are unavoidable issues occurring in high-speed gas microbearings due to the dominant small-scale fluid dynamics in rarefied gas flow applications. In this paper, thermo-elasto-aerodynamic analysis requires simultaneously solving the modified Reynolds equation, modified energy equation, temperature–viscosity relationship and the elasticity equations for predicting the lubrication characteristics of microbearings. A thermo-elasto-aerodynamic lubrication is systematically investigated by using the partial derivative method, finite difference formulation and the finite element approach. The results indicate that, compared with rigid microbearing which has a constant viscosity gas lubricant, the temperature effect increases the load capacity, friction coefficient and stiffness coefficients, and it decreases the attitude angle and damping coefficients of the microbearing. The flexibility of the bearing pad also leads to the increase in load capacity and direct stiffness coefficients, while it remains to further decrease the direct damping coefficients on the basis of thermo-aerodynamic performance. The present study is conducive to accurately analyze the microscopic flow properties in a microbearing-rotor system.

The Measurement of Pulsating Gas Flow Velocities Using Pseudorandom Pressure Pulses

1974 ◽  
Vol 7 (9) ◽  
pp. 346-348
Author(s):  
E. W. Reed ◽  
M. A. Ali ◽  
K. F. Gill
Keyword(s):  
Flow Velocity ◽  
Gas Flow ◽  
Binary Sequence ◽  
Mean Flow ◽  
Measuring Techniques ◽  
Pressure Pulses ◽  
Velocity Of Propagation ◽  
The Mean ◽  
Pulsating Gas Flow ◽  
Gas Flow Velocity

Demonstrated is an experimental means of measuring the mean flow velocity of a pulsating gas flow without the use of pipe constrictions. Small pseudo random binary sequence pressure pulses are injected into the flow. Correlation techniques are used to determine the velocity of propagation of these pulses from which the mean gas flow velocity can be calculated. The method is shown to be especially effective for high-velocity pulsating flows where measuring techniques at the present time are inadequate.

TEM evaluation of graded SixGe1-x heterolayers

1991 ◽  
Vol 49 ◽  
pp. 894-895
Author(s):  
N. David Theodore ◽  
Mamoru Tomozane ◽  
Ming Liaw
Keyword(s):  
Heterojunction Bipolar Transistors ◽  
Gas Flow ◽  
Field Effect Transistors ◽  
Chemical Vapor ◽  
Dark Field ◽  
Bipolar Transistors ◽  
Structural Quality ◽  
Weak Beam ◽  
Transmission Electron ◽  
And Behavior

There is extensive interest in SiGe for use in heterojunction bipolar transistors. SiGe/Si superlattices are also of interest because of their potential for use in infrared detectors and field-effect transistors. The processing required for these materials is quite compatible with existing silicon technology. However, before SiGe can be used extensively for devices, there is a need to understand and then control the origin and behavior of defects in the materials. The present study was aimed at investigating the structural quality of, and the behavior of defects in, graded SiGe layers grown by chemical vapor deposition (CVD).The structures investigated in this study consisted of Si1-xGex[x=0.16]/Si1-xGex[x= 0.14, 0.13, 0.12, 0.10, 0.09, 0.07, 0.05, 0.04, 0.005, 0]/epi-Si/substrate heterolayers grown by CVD. The Si1-xGex layers were isochronally grown [t = 0.4 minutes per layer], with gas-flow rates being adjusted to control composition. Cross-section TEM specimens were prepared in the 110 geometry. These were then analyzed using two-beam bright-field, dark-field and weak-beam images. A JEOL JEM 200CX transmission electron microscope was used, operating at 200 kV.

Electron Microscopy/Diffraction Study of the Ternary Mn-Er-S System

1990 ◽  
Vol 48 (1) ◽  
pp. 76-77
Author(s):  
A. R. Landa Canovas ◽  
L.C. Otero Diaz ◽  
T. White ◽  
B.G. Hyde
Keyword(s):  
Electron Microscopy ◽  
Gas Flow ◽  
Graphite Crucible ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Alumina Crucible ◽  
X Ray ◽  
Intermediate Phases ◽  
Twin Band ◽  
Ar Gas

X-Ray diffraction revealed two intermediate phases in the system MnS+Er2S3,:MnEr2S4= MnS.Er2S3, and MnEr4S7= MnS.2Er2S3. Their structures may be described as NaCl type, chemically twinned at the unit cell level, and isostructural with CaTi2O4, and Y5S7 respectively; i.e. {l13} NaCl twin band widths are (4,4) and (4,3).The present study was to search for structurally-related (twinned B.) structures and or possible disorder, using the more sensitive and appropiate technigue of electron microscopy/diffraction.A sample with nominal composition MnEr2S4 was made by heating Mn3O4 and Er2O3 in a graphite crucible and a 5% H2S in Ar gas flow at 1500°C for 4 hours. A small amount of this material was thenannealed, in an alumina crucible, contained in sealed evacuated silica tube, for 24 days at 1100°C. Both samples were studied by X-ray powder diffraction, and in JEOL 2000 FX and 4000 EX microscopes.

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