scholarly journals Supersonic flow of two-phase gas- droplet flows in nozzles

2019 ◽  
Vol 21 (3) ◽  
pp. 86-98
Author(s):  
A. I. Sharapov ◽  
A. A. Chernykh ◽  
A. V. Peshkova
Keyword(s):  
Liquid Mixtures ◽  
Rocket Engines ◽  
Two Phase ◽  
Acoustic Effect ◽  
Practical Applications ◽  
Wide Range ◽  
Phase Medium ◽  
Integral Energy ◽  
Energy Equations ◽  
Droplet Flows

For practical applications, the description of processes occurring during the flow of two-phase gas-liquid mixtures requires a simple physical and mathematical model that describes the behavior of a two-phase medium in the entire range of phase concentrations changes and in a wide range of pressure changes. Problems of this kind arise in various branches of industry and technology. In the space industry, one often has to deal with the movement of various gases in rocket nozzles, consider the combustion, condensation of various vapors on the nozzle walls and their further impact on the velocity sublayer at the nozzle wall. The large acoustic effect arising from the engines affects the gas-liquid mixture in the nozzles of rocket engines. In the metal industry, metal cooling occurs with the help of nozzles in which the emulsion mixture is supplied under high overpressure. But this is only a short list of applied issues in which one has to deal with a problem of this type. The paper presents the results and directions of study of the problems of two-phase dispersed gas-droplet flows in the nozzles. The main methods of investigation of two- phase heterogeneous flows are described. The main characteristics of heterogeneous two-phase flows in the nozzles, which were confirmed by experimental results, are presented. The calculation of the air-droplet flow in the Laval nozzle is given. The technique, which is based on integral energy equations for two-phase dispersed flows, is described. The main problems and questions concerning the further description and studying of two-component flows are stated.

scholarly journals Investigation of water-air flows in nozzles

2021 ◽  
Vol 2088 (1) ◽  
pp. 012006
Author(s):  
A A Chernykh ◽  
A I Sharapov ◽  
A G Arzamastsev ◽  
Y V Shatskikh
Keyword(s):  
Point Of View ◽  
Relaxation Processes ◽  
Two Phase ◽  
Ansys Fluent ◽  
Flow Parameters ◽  
Single Temperature ◽  
Phase Medium ◽  
Integral Energy ◽  
Drop Flow ◽  
Energy Equations

Abstract The undoubted importance of these problems allows us to conclude that the research aimed at creating and using a simple model of the flow of a two-phase medium is relevant and of interest not only from a scientific, but also from a practical point of view. Two approaches to their description can be distinguished: the study of flows of two-phase media taking into account relaxation processes between phases with a microscopic description of the interaction between phases, or the study of flows of two-phase media with a macroscopic description of the medium in the form of a one-speed one-temperature continuum. However, sometimes, when calculating, it is possible to ignore the structural two-phase medium and consider the medium as a one-speed one-temperature continuum. This proposal allows us to calculate the averaged flow parameters of a two-phase medium, which is required for engineering calculations. In this paper, the calculation of the flow of the gas-drop flow in the Laval nozzle is given. The method is described, which is based on integral energy equations for two-phase dispersed currents. In the calculations, the two-phase flow is considered as a single-speed, single-temperature continuum. When modeling in the ANSYS Fluent software package, a package of Euler equations is used to compare with analytical results obtained from integral energy equations.

Acoustic Properties of Solid-Liquid Mixtures and the Limits of Ultrasound Diagnostics—I: Experiments (Data Bank Contribution)

1993 ◽  
Vol 115 (4) ◽  
pp. 665-675 ◽  
Author(s):  
C. M. Atkinson ◽  
H. K. Kyto¨maa
Keyword(s):  
Spatial Resolution ◽  
Liquid Mixtures ◽  
Acoustic Properties ◽  
Present System ◽  
Linear Superposition ◽  
Two Phase ◽  
Ultrasound Diagnostics ◽  
Wide Range ◽  
Silica Beads ◽  
Solid Liquid

Ultrasound as a technique for interrogating two-phase mixtures has the advantages of being nonintrusive, it has a very high frequency response, and is able to penetrate typically opaque highly concentrated mixtures. There exists, however, an inherent compromise in the choice of the frequency of the ultrasound between maximizing spatial resolution and ensuring adequate beam penetration. To this end, the propagation of ultrasound in solid-liquid mixtures has been investigated experimentally for a range of frequencies and concentrations of the dispersed phase. The measured attenuation has been shown to depend roughly linearly on frequency for 0.1<kr<0.75 (where the wavenumber k = 2π/λ, and λ and r are the wavelength and particle radius, respectively), and quadratically for kr > 0.75. As a function of solids concentration, the attenuation displays a maximum at a solids fraction of about 30 percent for the present system of silica beads in water. This robust and reproducible result contradicts models of attenuation that rely on linear superposition of single particle effects. The intensity field produced by a circular disk transducer in a two phase medium at kr~1 shows excellent agreement with the Rayleigh integral with a modified wavenumber and attenuation parameter, and it allows for the prediction of the transducer beam geometry in two phase mixtures for a wide range of frequencies and solids fractions. The limitations of ultrasonic wave propagation as a nonintrusive diagnostic technique, in terms of spatial resolution, have been discussed. Acknowledging these limitations, an ultrasonic instrument for determining the velocity of moving particles at or near maximum packing was built. Preliminary results from this prototypical ultrasonic Doppler velocimeter show good agreement with observations of the settling velocity of silica beads at high concentrations.

Numerical Analysis of Cavitation Instabilities Arising in the Three-Blade Cascade

2004 ◽  
Vol 126 (3) ◽  
pp. 419-429 ◽  
Author(s):  
Yuka Iga ◽  
Motohiko Nohml ◽  
Akira Goto ◽  
Toshiaki Ikohagi
Keyword(s):  
Numerical Method ◽  
High Speed ◽  
Homogeneous Model ◽  
Rotating Stall ◽  
Two Phase ◽  
Wide Range ◽  
Phase Medium ◽  
Long Time ◽  
Entire Flow ◽  
Locally Homogeneous

Three types of cavitation instabilities through flat plate cascades, which are similar to “forward rotating cavitation,” “rotating-stall cavitation” and “cavitation surge” occurring in high-speed rotating fluid machinery, are represented numerically under the three-blade cyclic condition. A numerical method employing a locally homogeneous model of compressible gas-liquid two-phase medium is applied to solve the above flow fields, because this permits the entire flow field inside and outside the cavity to be treated through only one system of governing equations. In addition, the numerical method suites to analyze unsteady cavitating flow with a long time evolution. From the calculated results of the present numerical simulation with wide range of cavitation number and flow rate, we obtain a cavitation performance curve of the present three-blade cyclic cascade, analyze the aspects of unsteady cavitation, and discuss the characteristics and mechanisms of cavitation.

scholarly journals AGN Dusty Tori as a Clumpy Two-Phase Medium: the 10 μm Silicate Feature

2011 ◽  
Vol 20 (3) ◽  
Author(s):  
Marko Stalevski ◽  
Jacopo Fritz ◽  
Maarten Baes ◽  
Theodoros Nakos ◽  
Luka Č. Popović
Keyword(s):  
Three Dimensional ◽  
Galactic Nuclei ◽  
Infrared Emission ◽  
Spectral Energy ◽  
Two Phase ◽  
Random Arrangement ◽  
Wide Range ◽  
Phase Medium ◽  
Silicate Feature ◽  
Dust Distribution

AbstractWe investigated the emission of active galactic nuclei dusty tori in the infrared domain, with a focus on the 10 μm silicate feature. We modeled the dusty torus as a clumpy two-phase medium with high-density clumps and a low-density medium filling the space between the clumps. We used a three-dimensional radiative transfer code to obtain spectral energy distributions and images of tori at different wavelengths. We calculated a grid of models for different parameters and analyzed the influence of these parameters on the shape of the mid-infrared emission. A corresponding set of clumps-only models and models with a smooth dust distribution is calculated for comparison. We found that the dust distribution, the optical depth and a random arrangement of clumps in the innermost region, all have an impact on the shape and strength of the silicate feature. The 10 μm silicate feature can be suppressed for some parameters, but models with smooth dust distribution are also able to produce a wide range of the silicate feature strength.

A New Detector System For The HB5 Stem Instrument

1985 ◽  
Vol 43 ◽  
pp. 134-135
Author(s):  
J.M. Cowley
Keyword(s):  
Dark Field ◽  
Detector System ◽  
Electron Holography ◽  
Small Specimen ◽  
Bright Field ◽  
Multiple Images ◽  
Practical Applications ◽  
Wide Range ◽  
Diffraction Patterns ◽  
Operational Modes

The HB5 STEM instrument at ASU has been modified previously to include an efficient two-dimensional detector incorporating an optical analyser device and also a digital system for the recording of multiple images. The detector system was built to explore a wide range of possibilities including in-line electron holography, the observation and recording of diffraction patterns from very small specimen regions (having diameters as small as 3Å) and the formation of both bright field and dark field images by detection of various portions of the diffraction pattern. Experience in the use of this system has shown that sane of its capabilities are unique and valuable. For other purposes it appears that, while the principles of the operational modes may be verified, the practical applications are limited by the details of the initial design.

SYNTHESIS OF HYDROGEN IN ACOUSTOPLASMA DISCHARGE IN A LIQUID-PHASE STREAM

2019 ◽  
pp. 42-48 ◽  
Author(s):  
N. A. Bulychev
Keyword(s):  
Liquid Phase ◽  
Organic Compounds ◽  
Electrode Materials ◽  
Solid Phase ◽  
Plasma Discharge ◽  
Raw Material ◽  
Two Phase ◽  
Reduced Pressure ◽  
External Power Source ◽  
Phase Medium

In this paper, the plasma discharge in a high-pressure fluid stream in order to produce gaseous hydrogen was studied. Methods and equipment have been developed for the excitation of a plasma discharge in a stream of liquid medium. The fluid flow under excessive pressure is directed to a hydrodynamic emitter located at the reactor inlet where a supersonic two-phase vapor-liquid flow under reduced pressure is formed in the liquid due to the pressure drop and decrease in the flow enthalpy. Electrodes are located in the reactor where an electric field is created using an external power source (the strength of the field exceeds the breakdown threshold of this two-phase medium) leading to theinitiation of a low-temperature glow quasi-stationary plasma discharge.A theoretical estimation of the parameters of this type of discharge has been carried out. It is shown that the lowtemperature plasma initiated under the flow conditions of a liquid-phase medium in the discharge gap between the electrodes can effectively decompose the hydrogen-containing molecules of organic compounds in a liquid with the formation of gaseous products where the content of hydrogen is more than 90%. In the process simulation, theoretical calculations of the voltage and discharge current were also made which are in good agreement with the experimental data. The reaction unit used in the experiments was of a volume of 50 ml and reaction capacity appeared to be about 1.5 liters of hydrogen per minute when using a mixture of oxygen-containing organic compounds as a raw material. During their decomposition in plasma, solid-phase products are also formed in insignificant amounts: carbon nanoparticles and oxide nanoparticles of discharge electrode materials.

General Trend of Negative Transference Number in Li Salt/Ionic Liquid Mixtures

2019 ◽  
Author(s):  
Nicola Molinari ◽  
Jonathan P. Mailoa ◽  
Boris Kozinsky
Keyword(s):  
Ionic Liquid ◽  
Transference Number ◽  
Liquid Mixtures ◽  
Single Linkage ◽  
Self Diffusion ◽  
Wide Range ◽  
Single Linkage Cluster ◽  
Concentrated Solution ◽  
The One ◽  
Dynamics Simulations

We show that strong cation-anion interactions in a wide range of lithium-salt/ionic liquid mixtures result in a negative lithium transference number, using molecular dynamics simulations and rigorous concentrated solution theory. This behavior fundamentally deviates from the one obtained using self-diffusion coefficient analysis and agrees well with experimental electrophoretic NMR measurements, which accounts for ion correlations. We extend these findings to several ionic liquid compositions. We investigate the degree of spatial ionic coordination employing single-linkage cluster analysis, unveiling asymmetrical anion-cation clusters. Additionally, we formulate a way to compute the effective lithium charge that corresponds to and agrees well with electrophoretic measurements and show that lithium effectively carries a negative charge in a remarkably wide range of chemistries and concentrations. The generality of our observation has significant implications for the energy storage community, emphasizing the need to reconsider the potential of these systems as next generation battery electrolytes.<br>

Features of spatial shock-wave flows in vapor-gas-liquid mixtures

2014 ◽  
Vol 10 ◽  
pp. 27-31
Author(s):  
R.Kh. Bolotnova ◽  
U.O. Agisheva ◽  
V.A. Buzina
Keyword(s):  
Shock Wave ◽  
High Pressure ◽  
Shock Waves ◽  
Liquid Mixture ◽  
Liquid Mixtures ◽  
Pressure Vessels ◽  
Water Mixture ◽  
Two Dimensional ◽  
Nonstationary Processes ◽  
Two Phase

The two-phase model of vapor-gas-liquid medium in axisymmetric two-dimensional formulation, taking into account vaporization is constructed. The nonstationary processes of boiling vapor-water mixture outflow from high-pressure vessels as a result of depressurization are studied. The problems of shock waves action on filled by gas-liquid mixture volumes are solved.

Some 1-substitution derivatives of 4-aryl-2,3-dihalogeno-1-naphthols

1984 ◽  
Vol 49 (1) ◽  
pp. 110-121 ◽  
Author(s):  
Jiří Křepelka ◽  
Drahuše Vlčková ◽  
Milan Mělka
Keyword(s):  
Thionyl Chloride ◽  
Oxirane Ring ◽  
Secondary Amines ◽  
Two Phase ◽  
Lytic Effect ◽  
Primary And Secondary Amines ◽  
Phase Medium ◽  
Chloro Derivatives ◽  
Derivatives Of

Alkylation of derivatives of 4-aryl-1-naphthols (I-V) by 2,3-epoxypropyl chloride in methanolic sodium hydroxide gave epoxy derivatives VI, VIII, IX, XI and XII, apart from products of cleavage of the oxirane ring, VII and X. Analogous alkylation of compounds I, IV and V by 2-(N,N-diethylamino)ethyl chloride hydrochloride in a two-phase medium afforded basic ethers XIII to XV. The cleavage of the oxirane ring in compound VI by the action of primary and secondary amines, piperidine and substituted piperazines led to compounds XVI-XXIV. Reaction of thionyl chloride with compounds XXI, XXII and XXIV gave chloro derivatives XXV-XXVII.Exposure of compound XXII to 4-methylbenzenesulfonyl chloride produced compound XXVIII, retaining the secondary alcoholic group. In an antineoplastic screening in vivo none of the compounds prepared had an appreciable activity. Compound XVII, being an analogue of propranolol, was used in the test of isoproterenolic tachycardia, and showed a beta-lytic effect comparable with that of propranol.

Sign in / Sign up

Export Citation Format

Share Document