Simulation of the influence of surface chemical composition on internal gas flow at large Knudsen numbers

On the basis of the developed model, an attempt to describe a rarefied gas flow in the cylindrical channel, whose surface chemical composition conforms with the real experimental conditions, has been made. During the modeling two cases are considered: the atomically clean silver channel surface and the surface fully covered with the adsorbate, which is simulated by oxygen according to the data of the Auger-spectroscopic analysis. The gas-surface interaction process is based on the molecular dynamic principle. Thermal vibrations of the surface atoms are also considered. The obtained results of calculation are compared with experimental data. © Copyright 2013 Published by Elsevier Ltd. All rights reserved

NUMERICAL SMILATIONS OF GAS FLOWS CONSIDERING SURFACE ROUGH STRUCTTURE

In this paper we numerically simulated the motion of gas particles inside the cylindrical and rectangular channels considering the influence of micro-rough surface. Simulation was performed with two methods: the method of the test particle and the method o f direct statistical simulation

GAS FLOW PARAMETERS DISTRIBUTION IN IDEAL APERTURE. STATISTICAL MODELING METHOD

In this research we numerically simulated the gas flow throught the ideal apperture using direct simulation Monte-Carlo method. Gas flow features such as temperature and velocity profiles are investigated

GAS FLOW PARAMETERS DISTRIBUTION IN IDEAL APERTURE. RAY TRACING METHOD

Ray tracing method used to calculate parameters and velocities in the Knudsen flow through a perfect round hole. It is assumed that in the steady state volume of wall emit particles with the equilibrium Maxwellian distribution function with different numerical density and temperature

Neutralizer with a gas ejector

A neutralizer model with a gas ejector is studied, whose main element (a sonic nozzle) is a gap between two conical surfaces. Static pressure distributions were measured along the axis of the neutralizer at different gas pressures in the receiver. Stagnation pressure, total flow, gas target thickness, flow separation factor, Knudsen number, and gas-dynamic performance of the neutralizer were calculated from the gas pressure values on the axis of the neutralizer at the point with the coordinate z/d = 3, and static pressure distributions in the characteristic cross sections of the neutralizer were obtained. © 2012 Pleiades Publishing, Ltd

Generation of gas flows in symmetric neutralizer

This paper presents the results of experimental studies of the lengthwise distribution of the total and static pressure and the total flow of carbon dioxide in symmetrical neutralizers. These distributions are found to depend on the flow regimes and geometrical characteristics of gas injection. It is established that the density of the gas target per unit gas flow rate increases with increasing portion of the gas injected at the center of the neutralizes. © 2012 Pleiades Publishing, Ltd

The development of a high-precision environmentally friendly method for measuring the thickness of rolled sheets

A triangulation method for measuring the thickness of flaws with the guided radiation of a sounding signal and its reflection from the surface of a rolled sheet and reception in transducer's elements, which correspond to the measured thickness and other parameters of a rolled sheet, is considered. The high density of dust in the atmosphere of rolling mill stands and the thermal radiation of a heated rolled sheet are shown to be the principal disturbances in the measurement of such flaws by this method. For this reason, the spectral wavelengths adjacent to the IR imaging wavelength range, viz., thermovision and microwaves, are used in this triangulation method. The advantages and disadvantages of both existing and our coordinate measurement methods are demonstrated by the example of measuring the thickness of a metal sheet. © Pleiades Publishing, Ltd., 2012

The detection of flaws in optoelectronic systems (vol 48, pg 426, 2012)

Potentially dangerous spots (PDSs), for example, leaks in product pipelines (oil and gas pipelines), are revealed using optoelectronic systems (OESs) that are usually mounted on airborne vehicles (e.g., helicopters). Earlier, a relevant problem consisted of revealing the onset of leaks in PDSs; however, today it is necessary to detect the PDSs of leaks in order to prevent their development. The complexity of the problem is related to the fact that product pipelines are most often located near densely populated areas and near reservoirs with drinking water. The appearance of PDSs is usually characterized by deviations in the temperature and other physical parameters from standard values in small areas. The detection of such spots necessitates decreasing the flying height of an OES carrier. As a rule, this yields a deterioration of imaging quality and OES overheating, which decreases the efficiency of this PDS detection method. Conservative OES developers believe that a low imaging quality and OES overheating result from random flaws in the OES assembly. Contrary to this, it is shown that failures occur due to a deterministic flaw at the stage of designing drives for an OES platform