scholarly journals Development of calculation method and creation of vortex jet device to control gas flow

2019 ◽  
Vol 3 (2) ◽  
pp. 78-86
Author(s):  
A. Yu. Uss ◽  
◽  
A. V. Chernyshev ◽  
N. V. Atamasov ◽  
◽  
...  
Keyword(s):  
Calculation Method ◽  
Gas Flow

Gas flow calculation method of a ramjet engine

2017 ◽  
Author(s):  
Kirill Kostyushin ◽  
Anuar Kagenov ◽  
Ivan Eremin ◽  
Konstantin Zhiltsov ◽  
Vladimir Shuvarikov
Keyword(s):  
Calculation Method ◽  
Gas Flow ◽  
Flow Calculation ◽  
Ramjet Engine

Study on the Calculation Method of Gas Flow in Vacuum System Based on the Fluent Software

2010 ◽  
Vol 29-32 ◽  
pp. 1425-1429
Author(s):  
Shi Wei Zhang ◽  
Jin Ce Liu ◽  
Guang Zhe Song ◽  
Zhi Jun Zhang
Keyword(s):  
Laminar Flow ◽  
Calculation Method ◽  
Gas Flow ◽  
Volume Flow Rate ◽  
Fluid Velocity ◽  
Vacuum Field ◽  
Transitional Flow ◽  
Vacuum System ◽  
Continuity Hypothesis ◽  
Fluent Software

In order to improve the calculation method of the vacuum system design, the research focus on the way applying the Fluent software to calculation of gas flow in vacuum system in this paper. It is proved that the permission pressure lower limit is 1Pa for meeting the continuity hypothesis. The applicable flow patterns include turbulent flow, laminar flow and transitional flow between turbulent and laminar flow, which are totally defined as the viscous flow in the traditional vacuum field. By means of user define function (UDF), a layer mesh cell of negative quality source is defined to simulate the constant volume flow rate at the inlet of positive displacement vacuum pump, which makes up for the lack of compressible fluid velocity outlet boundary conditions in Fluent. The usability of Fluent in vacuum system is confirmed by a successful calculating example of gas flow in an ice condenser of vacuum freeze dryer.

Techniques and Methods to Improve the Dynamic Strength of Gas Turbine Engines Compressor Rotor Wheels

2014 ◽  
Author(s):  
Daria Kolmakova ◽  
Grigorii Popov ◽  
Aleksandr Shklovets ◽  
Aleksandr Ermakov
Keyword(s):  
Gas Turbine ◽  
Calculation Method ◽  
Gas Flow ◽  
Dynamic Strength ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Cfd Model ◽  
Compressor Blades ◽  
Compressor Rotor ◽  
Pressure Compressor

The approaches to reducing the alternating stresses in the compressor blades, arising at a resonance, are discussed in paper. Maximum alternating stresses in blades of the fifth stage of intermediate pressure compressor (IPC, that operating under the gas flow circumferential variation conditions, are defined on the basis of the forced blade oscillations calculation method. Parametric CFD-model which allows to introduce different stagger angles and circumferentially alternating blade pitch at the guide vanes of IPC fifth stage was created to reduce the stresses. The flow circumferential variation was reduced by changing these parameters and as a consequence the resonant stresses were decreased by more than 2.5 times.

Numerical Analysis of Unsteady Exhaust Gas Flow and Its Application for Lambda Control Improvement

2003 ◽  
Vol 125 (2) ◽  
pp. 555-562 ◽  
Author(s):  
K. Yoshizawa ◽  
K. Mori ◽  
K. Arai ◽  
A. Iiyama
Keyword(s):  
Feedback Control ◽  
Gas Exchange ◽  
Calculation Method ◽  
Gas Flow ◽  
Oxygen Sensor ◽  
Gasoline Engine ◽  
Control Method ◽  
Exhaust Gas ◽  
Exhaust Manifold ◽  
Flow Calculation

A multidimensional computational fluid dynamics (CFD) tool has been applied to analyze the exhaust system of a gasoline engine. Since gas flow in the exhaust manifold is affected by exhaust pulsations, prediction methods based on steady flow are not able to predict gas flow precisely enough. Therefore, a new multidimensional calculation method, called pulsation flow calculation, has been developed. A one-dimensional gas exchange simulation and a three-dimensional exhaust gas flow calculation are combined to simulate gas flow pulsations caused by the gas exchange process. Predicted gas flow in the exhaust manifold agreed with the experimental data. With the aim of reducing emissions, the pulsation flow calculation method has been applied to improve lambda feedback control using an oxygen sensor. The factors governing sensor sensitivity to the exhaust gas from each cylinder were clarified. The possibility of selecting the oxygen sensor location in the exhaust manifold on the basis of calculations was proved. The effect of an exhaust manifold with equal-length cylinder runners on achieving uniform sensor sensitivities was made clear. In addition, a new lambda feedback control method for an exhaust manifold with different-length cylinder runners is proposed.

A Calculation Method for the Quasi-Stationary Pressure in Cabin Explosion With Venting

2019 ◽  
Author(s):  
Pengduo Zhao ◽  
Haojie Wang ◽  
Zhipeng Du ◽  
Xiaobin Li
Keyword(s):  
Calculation Method ◽  
Gas Flow ◽  
Structural Strength ◽  
Simulation Method ◽  
Ideal Gas ◽  
Sharp Rise ◽  
Flow Process ◽  
Isentropic Compression ◽  
Long Duration ◽  
Release Model

Abstract The explosion in the closed cabin will cause a sharp rise in cabin gas pressure, which will cause serious damage to the cabin structure. The quasi-stationary pressure, due to its long duration and large impulse, plays a major role in the destruction of the structural strength of the entire cabin. The venting holes on the transverse bulkheads can effectively guide the release of energy to other locations, reducing the damage to the cabin. In this paper, the quasi-stationary pressure generated during cabin explosion with venting is studied. According to the conservation of mass and energy, the cabin explosion model with venting is transformed into an equivalent high pressure gas release model to simulate the initial instantaneous state of cabin explosion, and it is verified by finite element calculation that the two models are equivalent in predicting quasi-stationary pressure. The entire gas flow process during the exploding with venting holes is divided into two parts: the gas flow in the cabin to the venting hole and the venting hole to the atmosphere. An approximate analytical method for predicting quasi-stationary pressure generated during cabin explosion with venting is improved by using Bernoulli equation and isentropic compression formula of ideal gas, and the results of the improved calculation method are compared with the results obtained by the numerical simulation method to verify its validity.

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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