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Wyszukujesz frazę "two-phase flow" wg kryterium: Temat


Tytuł:
Numerical study of a polydisperse two-phase jet
Badania numeryczne polidyspersyjnej strugi dwufazowej
Autorzy:
Barata, J.
Perestrelo, N.
Powiązania:
https://bibliotekanauki.pl/articles/263159.pdf
Data publikacji:
2000
Wydawca:
Sieć Badawcza Łukasiewicz. Przemysłowy Instytut Motoryzacji
Tematy:
turbulent dispersion
two-phase flow
Opis:
Low emissions gas turbine combustors will demand fuel injection systems that are efficient in the accomplishment of the mixing of fuel and air in the shortest possible residence time. This paper describes a computational study of a polydisperse two-phase turbulent jet, which is the basic configuration to analyze how the various parameters influence the size distribution and the dispersion of the droplets in the injection process. An Eulerian frame for the for the gas phase was used in conjunction with a Lagrangian approach to describe both interphase slip and turbulence on particle motion. Good agreement of the computations with the experimental data is obtained for both the gas and the particles turbulence modulation and anisotropy effects were introduced and were found to be very important to the successful performance of the computational method. The exchange of monumentum and turbulence energy between the two phases was shown to play a decisive role on the flow development. The predictions confirmed the measurements and showed that the particles do not follow the turbulent gas flow, but they affect it significantly. Considerably high values of the radial velocity were detected around the centerline far from the jet exit where the velocity of the particles lags that of the fluid, that seems to be associated with the effect of shear induced lift forces.
Przedstawiono studium komputerowe polidyspersyjnej dwufazowej strugi turbulentnej, które jest bazą wyjściową do oceny wpływu różnych parametrów na rozkład średnicy kropel podczas wtrysku do ośrodka gazowego. Wykorzystano Eulerowską analizę do fazy gazowej oraz analizę Lagrange'a do obliczania drogi cząstek. Uzyskane wyniki obliczeniowe są zgodne z eksperymentalnymi. Turbulencja i niejednorodność średnic kropel mają istotny wpływ na rozwój strumienia. Stwierdzono także, że składowe promieniowe prędkości z daleka od otworu rozpylacza uzyskują wysokie wartości.
Źródło:
Archiwum Motoryzacji; 2000, 2; 113-125
1234-754X
2084-476X
Pojawia się w:
Archiwum Motoryzacji
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
CFD simulation as a tool for the identification of the manifold element reaction to pressure pulsations excitation (one- and two-phase flow)
Autorzy:
Cyklis, P.
Kantor, R.
Powiązania:
https://bibliotekanauki.pl/articles/1955745.pdf
Data publikacji:
2003
Wydawca:
Politechnika Gdańska
Tematy:
pressure pulsations
two-phase flow
CFD
Opis:
The periodicity of compressor operation is a source of pressure pulsations in volumetric compressor manifolds. An analysis of pressure pulsations is important for several reasons. The Helmholtz model, applied in all commercial programs offered by the companies professionally dealing with damping pressure pulsations, contains numerous simplifying assumptions; a straight pipe segment, with an ideal gas isentropic flow assumption, substitutes each element of the piping system. In many cases this model is insufficient. The existing experimental methods could not be used in the design of a muffler. The aim of this paper is to show a new method to identify an arbitrary fragment of a manifold, i.e. a method of identification of the appropriate complex transmittance matrix elements using CFD simulation. This method allows the liquid phase dispersed in the compressed gas and non ideal gas as a working medium to also be considered. The most important conclusion of this work is that identification of acoustic element parameters in the manifold, based on multi-dimensional simulation model, is feasible. The author obtained much better results from the developed method than those yielded by the classic Helmholtz model. A comparison between pure gas and gas with oil contamination is also shown in the paper.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2003, 7, 3; 363-374
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatial distribution and settling velocity of heavy particles in synthetic turbulent fields
Autorzy:
Łuniewski, M.
Pozorski, J.
Powiązania:
https://bibliotekanauki.pl/articles/175528.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
two-phase flow
heavy particles
turbulent dispersion
Opis:
We analyse numerically the motion of small inertial particles, subject to gravity, in two simple velocity fields: two-dimensional cellular flow, and a three-dimensional flow being the superposition of random Fourier velocity modes. The latter, also known as the kinematic simulation or synthetic turbulence, has often been applied in various studies, including those aiming to predict particle dispersion. The interplay of the particle inertia and the acceleration of gravity has non-trivial consequences for trajectories of particles and their spatial distribution, known as a preferential concentration. Also, we compute the average settling velocity of particles in function of their inertia and the number of fluid velocity modes used in simulations. The present paper aims to study these efects, as the synthetic turbulence represents an interesting option for subfilter modeling in particle-laden large-eddy simulation.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2017, 135; 87-100
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical Simulation of One-Dimensional Two-Phase Flow in Porous Media
Autorzy:
Szymkiewicz, A.
Powiązania:
https://bibliotekanauki.pl/articles/241426.pdf
Data publikacji:
2007
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
two-phase flow
porous media
numerical methods
Opis:
The flow of two immiscible fluids in porous media is described by two coupled non-linear partial differential equations of the parabolic type. In this paper a numerical algorithm to simulate one-dimensional two-phase flow is presented. Cell-centered finite volume method and a generalized two-level scheme with weighting parameter are applied for the discretization in space and time, respectively. The performance of the algorithm is tested for different values of the weighting parameter in the time-discretization scheme and for various methods of approximation of the average conductivities between two adjacent gridblocks. The results are compared with an analytical solution for the horizontal flow and with a reference numerical solution performed on a dense grid for the vertical flow.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2007, 54, 2; 117-136
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Turbulent mixing of a cloud wit h the enviranment: two-phase evaporating flow. Numerical simulations, laboratory experiments and field measurements
Turbulencyjne mieszanie chmury z otoczeniem jako przepływ dwufazowy z parowaniem. Symulacje numeryczne, eksperymenty laboratyjne i pomiary in situ
Autorzy:
Malinowski, S. P.
Powiązania:
https://bibliotekanauki.pl/articles/279222.pdf
Data publikacji:
2007
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
two-phase flow
turbulent mixing
cloud interface
Opis:
A brief overview of numerical simulations, laboratory experiments and in-situ measurements aimed at investigation of the cloud-clear air interfacial-mixing, conducted in recent years at the Institute of Geophysics, University of Warsaw is presented. The most interesting finding from these studies is that the evaporative cooling at the interface separating cloudy and clear filaments results in density differences in scale of centimeters. This effect influences smallest scales of turbulent motions through production of TKE by buoyancy forces and makes the small-scale turbulence anisotropic.
W artykule zawarto zwarty przegląd symulacji numerycznych, eksperymentów prowadzonych w laboratorium oraz pomiarów in situ, których celem było badanie mieszania turbulencyjnego na granicy chmury z nienasyconym otoczeniem. Badania te prowadzono w Instytucie Geofizyki Uniwersytetu Warszawskiego. Najciekawszym wynikiem tych prac jest pokazanie wpływu, jaki ma parowanie wody chmurowej na granicy chmury na dynamikę turbulencji w małych skalach. Parowanie powoduje powstanie lokalnych różnic gęstości o skali przestrzennej rzędu centymetrów. Działanie sił wyporu prowadzi do produkcji drobnoskalowej turbulencji. Ponieważ wyróżniony jest kierunek pionowy, turbulencja ta jest anizotropowa.
Źródło:
Journal of Theoretical and Applied Mechanics; 2007, 45, 3; 587-601
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of a discretization scheme on an autoignition time in LES of a reacting droplet-laden mixing layer
Autorzy:
Stempka, J.
Kuban, L.
Tyliszczak, A.
Powiązania:
https://bibliotekanauki.pl/articles/38621390.pdf
Data publikacji:
2021
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
autoignition process
two-phase flow
mixing layer
Opis:
We analyse an autoignition process in a two-phase flow in a temporally evolving mixing layer formed between streams of a cold liquid fuel (heptane at 300 K) and a hot oxidizer (air at 1000 K) flowing in opposite directions. We focus on the influence of a discretization method on the prediction of the autoignition time and evolution of the flame in its early development phase. We use a high-order code based on the 6th order compact difference method for the Navier–Stokes and continuity equations combined with the 2nd order Total Variation Diminishing (TVD) and 5th order Weighted Essentially Non-Oscillatory (WENO) schemes applied for the discretization of the advection terms in the scalar transport equations. The obtained results show that the autoignition time is more dependent on the discretization method than on the flow initial conditions, i.e., the Reynolds number and the initial turbulence intensity. In terms of mean values, the autoignition occurs approximately 15% earlier when the TVD scheme is used. In this case, the ignition phase characterizes a sharp peak in the temporal evolution of the maximum temperature. The observed differences are attributed to a more dissipative character of the TVD scheme. Its usage leads to a higher mean level of the fuel in the gaseous form and a smoother distribution of species resulting in a lower level of the scalar dissipation rate, which facilitates the autoignition process.
Źródło:
Archives of Mechanics; 2021, 73, 2; 153-174
0373-2029
Pojawia się w:
Archives of Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling of selected phenomena governing surface icing
Autorzy:
Sznajder, J.
Powiązania:
https://bibliotekanauki.pl/articles/248155.pdf
Data publikacji:
2013
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
icing
transport
air transport
simulation
two-phase flow
Opis:
Atmospheric icing poses a threat for safety in many areas of transport, especially in air transport and exerts harmful impact on operation of external sensors and mechanisms of aircraft, ships and land vehicles. In order to investigate phenomena leading to ice accretion on sensitive parts of objects exposed to icing conditions numerical simulation models are in use. These models are typically composed of submodels dealing with a fragment of the complex phenomenon of ice accretion and its interaction with external flow. A practical approach to simulation of icing process is to divide it into three problems being solved interactively: 1) simulation of two-phase flow of air and dispersed supercooled water and determination of distribution of mass of water hitting the object’s surface, 2) determination of conditions on the surface collecting supercooled water from the external flow and simulation of freezing and water film flow, and 3) modification of computational grid as a consequence of change of shape of the surface with deposits of ice. A simulation system directed at investigation of atmospheric icing on moving object is being developed as an extension of capabilities of a commercial CFD code ANSYS FLUENT. Solutions of two-phase flow of air and dispersed water with specific boundary conditions enabling the determination of distribution of water hitting the surface, as well as results of modelling of water film flow on the surface will be presented. The system of equations describing the transport of the dispersed water consists of the continuity and momentum equations. It is assumed, that interactions between the phases are onedirectional, i.e. the air flow influences the water droplet flow and not vice-versa. It is also assumed that the water film velocity distribution is linear in direction normal to surface. This way, both phenomena are being described with first order partial differential equations with respect to space and time and the solution approaches may be similar.
Źródło:
Journal of KONES; 2013, 20, 2; 377-384
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of stereology for assessment of two-phase flow structures
Autorzy:
Masiukiewicz, M.
Ulbrich, R.
Zając, D.
Powiązania:
https://bibliotekanauki.pl/articles/175510.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
stereological analysis
two-phase flow pattern
pattern recognition
Opis:
This paper describes a method for two-phase flow structures evaluation of gas-liquid mixture based on theoretical assumptions for the stereology in materials science. This assessment is based on the analysis of digital images, obtained with a high-speed camera. The bright field technique was used for process visualization. The images obtained during the visualisation were, in fact, projections of the structures. For the given recording conditions, the stereological analysis applied was based on the linear method and on the method of random and directed secants. The new methods of determining important parameters of two-phase flow were proposed on the basis of collected data. The parameters are as follows: the volume fraction, the interfacial area, the number of objects in one of the phases of the mixture and two other structural parameters of the selected two-phase fluid obtained from the analysis of the two-dimensional image (average length of chords for projected objects, average free distance for convex shapes from the projection).
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2013, 125; 39-54
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simplified Volume of Fluid Method (SVOF) for two-phase flows
Autorzy:
Marek, M.
Aniszewski, W.
Bogusławski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1943237.pdf
Data publikacji:
2008
Wydawca:
Politechnika Gdańska
Tematy:
two-phase flow modeling
volume of fluid
eulerian simulation
Opis:
The PLIC approach has been usually used in recent implementations of the VOF method i.e. the interphasal surface is approximated by a plane with an arbitrary orientation with respect to the computational cell. Although this method is accurate, it is rather difficult to implement, as a large number of orientations need to be taken into account and the calculation of volume fraction fluxes is not straightforward. A simpler approach to VOF – SLIC – requires much less effort from the programmer but the interface approximation by a plane parallel to the cell surfaces is too crude and the results are not satisfactory. The method presented in the article may be considered as an intermediate approach between PLIC and SLIC – fluxes are computed directly only for the interface’s special orientations and linear interpolation is used for calculation of the fluxes for the remaining cases. Some classical tests of the proposed method are performed and an example of a broken dam problem simulation is presented.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2008, 12, 3-4; 255-265
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of wettability on oil recovery
Autorzy:
Kulynych, V.
Powiązania:
https://bibliotekanauki.pl/articles/1203993.pdf
Data publikacji:
2015
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
wettability
contact angle
relative permeability
EOR
two-phase flow
Opis:
Understanding the mechanism by which oil is displaced from the porous medium requires knowledge about the role of wetting and capillary forces during EOR. Knowledge of the effect of wettability on oil production is also a key point for understanding the behavior of multiphase flows in the reservoir. A literature review indicates that wettability is one of the ma in factors controlling and regulating the distribution of oil and water in the reservoir rock. Therefore, the resolution of problems associated with the calculation of oil resources, operation and analysis of core deposits, must take into account the wettability of rock. Therefore, the study of such phenomena as wettability is still valid today. In the paper reservoir rock wettability and its types were desc ribed. Direct and indirect methods of determining the wettability were characterized, the graph of capillary pressure is used to characterize the wettability. In order to determine the effect of wettability on multiphase flow in porous media are discussed petrophysical parameters: capillary pressure, relative permeability and hydrocarbon saturation of the rock. Characterized wettability of each of Characterized wettability of each of carbonate and sandstone reservoirs.
Źródło:
AGH Drilling, Oil, Gas; 2015, 32, 3; 493-502
2299-4157
2300-7052
Pojawia się w:
AGH Drilling, Oil, Gas
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical study of droplet formation in a Y-junction microchannel
Autorzy:
Diouf, M. M. L.
Romero, O. J.
Powiązania:
https://bibliotekanauki.pl/articles/281676.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
microfluidic
Y-junction
two-phase flow
numerical simulation
VOF
Opis:
This study investigates the formation process of droplets in a Y-junction microchannel using two immiscible fluids: water as the continuous fluid and oil as the dispersed phase. We have examined the influence of the capillary number, flow rate ratio and viscosity ratio between the two fluids; parameters which determine the length and generation frequency of the droplets. Numerical simulations have been performed using the software Ansys Fluent with the interface capture method Volume of Fluid (VOF) for solving the governing equations. Three different algorithms have been tested for the pressure-velocity coupling: SIMPLE, SIMPLEC and PISO. The results are quite similar for SIMPLE and SIMPLEC, however it turned out that PISO is a better algorithm to solve the two-phase flow. Additionally, another Y-junction is coupled in the initial geometry to observe a symmetric breakup of the droplets and their formation is explained using the pressure field and the velocity field.
Źródło:
Journal of Theoretical and Applied Mechanics; 2017, 55, 1; 317-330
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysing the cavitation phenomena in in-nozzle flows
Autorzy:
Vajda, B.
Žunič, Z.
Kegl, B.
Powiązania:
https://bibliotekanauki.pl/articles/247508.pdf
Data publikacji:
2010
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
two-phase flow
cavitation
injector nozzle
CFD
nodalisation analysis
Opis:
The geometry of the diesel fuel injection nozzle and fuel flow characteristics in the nozzle significantly affects the processes of fuel atomization, combustion and formation of pollutant emissions in diesel engine. To improve the process of fuel injection, CFD packages are used. Since CPU times are often high, partial models are used for the analysis. In presented paper the influence ,of different density of mesh on the cavitation phenomena is being analysed. The theoretical backgrounds of the cavitation occurrence presented in the first part of the paper are followed by the numerical analyses of two-phase flow in same simplified nozzle models. The numerical analyses are made using computation fluid dynamic (CFD) program Fire. The numerical analysis is made for two different types of fluid, diesel (D2) and biodiesel (B 100). Numerical analysis also includes various densities of meshes and their influence on results. The two-phase flow is analysed using a two-equation approach, where all conservation equations are solved for every phase. Numerical analysis results are compared to the experimental observations of the two-phase flow available from the literature. The results are compared for various meshes and various fluid types. The results show that higher pressure yields mode cavitation and point out the importance of mesh densities.
Źródło:
Journal of KONES; 2010, 17, 2; 475-482
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diffusive–inertial droplet separation model from two-phase flow
Autorzy:
Mikielewicz, Jarosław
Dolna, Oktawia
Kwidziński, Roman
Powiązania:
https://bibliotekanauki.pl/articles/1955019.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
two-phase flow
diffusive-inertial droplet separation
stopping distance
Opis:
This paper concerns analytical considerations on a complex phenomenon which is diffusive-inertial droplet separation from the twophase vapour-liquid flow which occurs in many devices in the power industry (e.g. heat pumps, steam turbines, organic Rankine cycles, etc.). The new mathematical model is mostly devoted to the analysis of the mechanisms of diffusion and inertia influencing the distance at which a droplet separates from the two-phase flow and falls on a channel wall. The analytical model was validated based on experimental data. The results obtained through the analytical computations stay in a satisfactory agreement with available literature data.
Źródło:
Archives of Thermodynamics; 2021, 42, 3; 141-158
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Computer cooling using a two phase minichannel thermosyphon loop heated from horizontal and vertical sides and cooled from vertical side
Autorzy:
Bieliński, H.
Mikielewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/240497.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
obieg termosyfonowy
przepływu dwufazowy
thermosyphon loop
two phase flow
Opis:
In the present paper it is proposed to consider the computer cooling capacity using the thermosyphon loop. A closed thermosyphon loop consists of combined two heaters and a cooler connected to each other by tubes. The first heater may be a CPU processor located on the motherboard of the personal computer. The second heater may be a chip of a graphic card placed perpendicular to the motherboard of personal computer. The cooler can be placed above the heaters on the computer chassis. The thermosyphon cooling system on the use of computer can be modeled using the rectangular thermosyphon loop with minichannels heated at the bottom horizontal side and the bottom vertical side and cooled at the upper vertical side. The riser and a downcomer connect these parts. A one-dimensional model of two-phase flow and heat transfer in a closed thermosyphon loop is based on mass, momentum, and energy balances in the evaporators, rising tube, condenser and the falling tube. The separate two-phase flow model is used in calculations. A numerical investigation for the analysis of the mass flux rate and heat transfer coefficient in the steady state has been accomplished.
Źródło:
Archives of Thermodynamics; 2010, 31, 4; 51-59
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Weryfikacja metod obliczania udziału objętościowego gazu
Verification of methods used for gas volume fraction calculation
Autorzy:
Czernek, K.
Okoń, P.
Powiązania:
https://bibliotekanauki.pl/articles/2073324.pdf
Data publikacji:
2018
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
udział objętościowy
przepływ dwufazowy
volume fraction
two-phase flow
Opis:
Przedstawiono wyniki obliczeń wpływu parametrów hydrodynamicznych na udział objętościowy faz podczas przepływu w rurach pionowych mieszaniny dwufazowej gazu i cieczy. Dokonano oceny dokładności wybranych metod obliczeniowych uwzględniających parametry hydrodynamiczne i określono przydatność metod w obliczeniach procesowych aparatów wykorzystujących tę formę przepływu.
The calculation results of hydrodynamic parameters’ impact on a volume fraction in gas-liquid two-phase flow in vertical pipes are presented in the paper. The accuracy of selected calculation methods cited in literature was evaluated for various hydrodynamic parameters. The usefulness and accuracy of these methods in process calculations of apparatus in which this type of flow exist were determined.
Źródło:
Inżynieria i Aparatura Chemiczna; 2018, 3; 51--52
0368-0827
Pojawia się w:
Inżynieria i Aparatura Chemiczna
Dostawca treści:
Biblioteka Nauki
Artykuł

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