The study of the process of evolution of the jet under outflow of water from the supercritical state through a thin nozzle

2016 ◽  
Vol 11 (1) ◽  
pp. 66-71 ◽  
Author(s):  
R.Kh. Bolotnova ◽  
V.A. Korobchinskaya
Keyword(s):  
Stationary Process ◽  
Supercritical State ◽  
System Of Differential Equations ◽  
Jet Formation ◽  
Cylindrical Coordinates ◽  
Initial Stage ◽  
Supersonic Regime ◽  
Water Outflow ◽  
Thin Nozzle ◽  
Supercritical Temperature

The dynamics of the water outflow from the initial supercritical state through a thin nozzle is studied. To describe the initial stage of non-stationary process outflow the system of differential equations of conservation of mass, momentum and energy in a two-dimensional cylindrical coordinates with axial symmetry is used. The spatial distribution of pressure and velocity of jet formation was received. It was established that a supersonic regime of outflow at supercritical temperature of 650 K is formed, which have a qualitative agreement for the velocity compared with the Bernoulli analytical solution and the experimental data.

Study the dynamics of hollow jet formation under vapor outflow from the supercritical state

2018 ◽  
Vol 13 (4) ◽  
pp. 73-78
Author(s):  
R.Kh. Bolotnova
Keyword(s):  
Water Vapor ◽  
Equation Of State ◽  
Numerical Study ◽  
Cavity Formation ◽  
Supercritical State ◽  
Two Dimensional ◽  
Jet Formation ◽  
Unsteady Process ◽  
Thin Nozzle ◽  
Robinson Equation

The features of the unsteady process of a cavity formation inside the jet at a sudden outflow of water vapor through a thin nozzle from a pressure vessel, initially in a supercritical state, are studied. A numerical study was carried out by using the sonicFoam solver of the OpenFOAM library with the Peng-Robinson equation of state in a two-dimensional axisymmetric approximation. Visualization of the obtained solutions is presented in the form of pictures dynamics for fields of velocities and temperatures. It is shown that the mode of formation and maintenance of the cavity inside the jet is supported more than 100 μs from the beginning of the expiration process.

The Initial Stage of Diffuse Jet Formation in a Pulsed Discharge with a Non-Uniform Electric Field in Air

2019 ◽  
Vol 32 (5) ◽  
pp. 607-611
Author(s):  
V. S. Kuznetsov ◽  
V. F. Tarasenko ◽  
V. A. Panarin ◽  
V. S. Skakun ◽  
E. A. Sosnin ◽  
...  
Keyword(s):  
Electric Field ◽  
Uniform Electric Field ◽  
Pulsed Discharge ◽  
Jet Formation ◽  
Initial Stage

Simulation the formation process of boiling water flow during depressurization of a high pressure vessel using OpenFoam open source

2017 ◽  
Vol 12 (2) ◽  
pp. 169-173 ◽  
Author(s):  
R.Kh. Bolotnova ◽  
V.A. Korobchinskaya
Keyword(s):  
Open Source ◽  
High Speed ◽  
Numerical Study ◽  
Mass Conservation ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Speed Flow ◽  
Initial Stage ◽  
Calculation Results ◽  
Water Outflow

A numerical study of the initial stage of water outflow process through a thin nozzle from a supercritical state in a two-dimensional axisymmetric setting is performed using the OpenFOAM software open source with the sonicFoam solver. The mathematical model of sonicFoam solver includes the equation of mass conservation, Navier-Stokes equation, internal energy conservation and equation of state of water vapor in the form of a perfect gas. Visualization of calculation results was carried out by the ParaView graphic platform. The features of supersonic high-speed flow regime in a jet accompanied by the formation of a hollow jet in a form close to parabolic are investigated.

Reaction couples of ceramic thin films prepared by CVD

1988 ◽  
Vol 46 ◽  
pp. 798-799
Author(s):  
D.W. Susnitzky ◽  
S.R. Summerfelt ◽  
C.B. Carter
Keyword(s):  
Thin Film ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Solid State Reactions ◽  
Spatial Distributions ◽  
Diffusion Couples ◽  
Kinetics Studies ◽  
Ceramic Thin Films ◽  
Initial Stage

Solid-state reactions have traditionally been studied in the form of diffusion couples. This ‘bulk’ approach has been modified, for the specific case of the reaction between NiO and Al2O3, by growing NiAl2O4 (spinel) from electron-transparent Al2O3 TEM foils which had been exposed to NiO vapor at 1415°C. This latter ‘thin-film’ approach has been used to characterize the initial stage of spinel formation and to produce clean phase boundaries since further TEM preparation is not required after the reaction is completed. The present study demonstrates that chemical-vapor deposition (CVD) can be used to deposit NiO particles, with controlled size and spatial distributions, onto Al2O3 TEM specimens. Chemical reactions do not occur during the deposition process, since CVD is a relatively low-temperature technique, and thus the NiO-Al2O3 interface can be characterized. Moreover, a series of annealing treatments can be performed on the same sample which allows both Ni0-NiAl2O4 and NiAl2O4-Al2O3 interfaces to be characterized and which therefore makes this technique amenable to kinetics studies of thin-film reactions.

Decoration technique and surface physics

1978 ◽  
Vol 36 (1) ◽  
pp. 436-437 ◽  
Author(s):  
H. Bethge
Keyword(s):  
Diffusion Path ◽  
Special Importance ◽  
Surface Physics ◽  
Step Structure ◽  
Initial Stage ◽  
Special Cases ◽  
Atomic Surface ◽  
The Mean ◽  
Bulk Structure ◽  
Decoration Technique

Besides the atomic surface structure, diverging in special cases with respect to the bulk structure, the real structure of a surface Is determined by the step structure. Using the decoration technique /1/ it is possible to image step structures having step heights down to a single lattice plane distance electron-microscopically. For a number of problems the knowledge of the monatomic step structures is important, because numerous problems of surface physics are directly connected with processes taking place at these steps, e.g. crystal growth or evaporation, sorption and nucleatlon as initial stage of overgrowth of thin films.To demonstrate the decoration technique by means of evaporation of heavy metals Fig. 1 from our former investigations shows the monatomic step structure of an evaporated NaCI crystal. of special Importance Is the detection of the movement of steps during the growth or evaporation of a crystal. From the velocity of a step fundamental quantities for the molecular processes can be determined, e.g. the mean free diffusion path of molecules.

Nucleation and initial growth of Pd2Si crystals on Si(111)

1993 ◽  
Vol 51 ◽  
pp. 844-845
Author(s):  
Xianghong Tong ◽  
Oliver Pohland ◽  
J. Murray Gibson
Keyword(s):  
High Vacuum ◽  
Dark Field ◽  
Ultra High Vacuum ◽  
Initial Growth ◽  
Surface And Interface ◽  
Dark Field Imaging ◽  
Transmission Electron ◽  
Initial Stage ◽  
Effect Of Surface

The nucleation and initial stage of Pd2Si crystals on Si(111) surface is studied in situ using an Ultra-High Vacuum (UHV) Transmission Electron Microscope (TEM). A modified JEOL 200CX TEM is used for the study. The Si(111) sample is prepared by chemical thinning and is cleaned inside the UHV chamber with base pressure of 1x10−9 τ. A Pd film of 20 Å thick is deposited on to the Si(111) sample in situ using a built-in mini evaporator. This room temperature deposited Pd film is thermally annealed subsequently to form Pd2Si crystals. Surface sensitive dark field imaging is used for the study to reveal the effect of surface and interface steps.The initial growth of the Pd2Si has three stages: nucleation, growth of the nuclei and coalescence of the nuclei. Our experiments shows that the nucleation of the Pd2Si crystal occurs randomly and almost instantaneously on the terraces upon thermal annealing or electron irradiation.

Anisotropy of interfacial defects in the initial stage of MOVPE GaAs growth On Si

1990 ◽  
Vol 48 (4) ◽  
pp. 592-593
Author(s):  
C. Vannuffel ◽  
C. Schiller ◽  
J. P. Chevalier
Keyword(s):  
Early Stage ◽  
Threading Dislocations ◽  
Mbe Growth ◽  
Detailed Mechanism ◽  
Si Substrates ◽  
Initial Stage ◽  
Interfacial Defects ◽  
Interfacial Dislocations ◽  
Step Growth ◽  
Essential Problem

Recently, interest has focused on the epitaxy of GaAs on Si as a promising material for electronic applications, potentially for integration of optoelectronic devices on silicon wafers. The essential problem concerns the 4% misfit between the two materials, and this must be accommodated by a network of interfacial dislocations with the lowest number of threading dislocations. It is thus important to understand the detailed mechanism of the formation of this network, in order to eventually reduce the dislocation density at the top of the layers.MOVPE growth is carried out on slightly misoriented, (3.5°) from (001) towards , Si substrates. Here we report on the effect of this misorientation on the interfacial defects, at a very early stage of growth. Only the first stage, of the well-known two step growth process, is thus considered. Previously, we showed that full substrate coverage occured for GaAs thicknesses of 5 nm in contrast to MBE growth, where substantially greater thicknesses are required.

Mechanism of irregular crack-propagation in thermal controlled fracture of ceramics induced by microwave

2020 ◽  
Vol 21 (6) ◽  
pp. 610
Author(s):  
Xiaoliang Cheng ◽  
Chunyang Zhao ◽  
Hailong Wang ◽  
Yang Wang ◽  
Zhenlong Wang
Keyword(s):  
Crack Propagation ◽  
Industrial Application ◽  
Ceramic Materials ◽  
Advanced Technology ◽  
Analytical Models ◽  
Propagation Mechanism ◽  
Unstable Crack ◽  
Fracture Simulation ◽  
Initial Stage ◽  
Controlled Fracture

Microwave cutting glass and ceramics based on thermal controlled fracture method has gained much attention recently for its advantages in lower energy-consumption and higher efficiency than conventional processing method. However, the irregular crack-propagation is problematic in this procedure, which hinders the industrial application of this advanced technology. In this study, the irregular crack-propagation is summarized as the unstable propagation in the initial stage, the deviated propagation in the middle stage, and the non-penetrating propagation in the end segment based on experimental work. Method for predicting the unstable propagation in the initial stage has been developed by combining analytical models with thermal-fracture simulation. Experimental results show good agreement with the prediction results, and the relative deviation between them can be <5% in cutting of some ceramics. The mechanism of deviated propagation and the non-penetrating propagation have been revealed by simulation and theoretical analysis. Since this study provides effective methods to predict unstable crack-propagation in the initial stage and understand the irregular propagation mechanism in the whole crack-propagation stage in microwave cutting ceramics, it is of great significance to the industrial application of thermal controlled fracture method for cutting ceramic materials using microwave.

Natural Language and a Computer System in Medical Research*)

1979 ◽  
Vol 18 (01) ◽  
pp. 15-17 ◽  
Author(s):  
Ileana C. Johnson ◽  
S. L. Tsao ◽  
I. D. J. Bross ◽  
D. P. Shedd
Keyword(s):  
Head And Neck Cancer ◽  
Natural Language ◽  
Roswell Park Memorial Institute ◽  
Basic Form ◽  
Specialized Knowledge ◽  
Complete Control ◽  
Processing Data ◽  
Remote Terminal ◽  
Initial Stage ◽  
Cancer Project

A series of computer programs are now available for processing data whose basic form is narrative (natural language), numerical or a combination of the two. This system was developed in the Department of Biostatistics of Roswell Park Memorial Institute, to enable an investigator to have complete control of the data — from the initial stage of entering the data to the final stage of analysis. Specialized knowledge of computers is not necessary in order to implement the different procedures. By following the instructions specified in various manuals and by basically just pushing a button of a remote terminal the procedures are activated and executed. This system is actually used for maintaining the data of a head and neck cancer project.

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