Wyniki wyszukiwania - BazTech

1

Mathematical models of hydromechanics of multiphase flow with varying mass

Mamedov Gasim A., Abbasov Natiq M.

Nafta-Gaz

|

2023

|

R. 79, nr 11

709--715

EN

The paper discusses the mathematical model of hydromechanics of multiphase flows with varying mass. A multiphase flow is considered a continuum consisting of a set of a large number of different groups of particles. The derivation of motion equations and similarity criteria are given taking into account both the externally attached (or detached) mass and phase transitions within the medium. The equations of mass, momentum and energy transfer for individual phases and the medium as a whole are derived based on fundamental conservation laws. It was demonstrated that in the absence of sources (or flow-offs) of mass, momentum and energy, the known equations of single- and multi-phase flow hydromechanics follow as a special case from the obtained systems of motion equations and similarity criteria. The obtained motion equations are valid for the description of an ingredient of mixture and the medium as a whole, regardless of their physical and mechanical properties. Thermodynamic and rheological state equations, as well as expressions for heat flow, interfacial mass forces phase transitions, and heat exchange between phases can be used to close them. The implemented models make it possible to simulate both the stationary distribution of parameters along the wellbore during production and non-stationary processes that occur, for example, when the pump shaft speed changes during oil production. The developed approaches were implemented in the DataFlow software tool for analysis of the hydrodynamics of multiphase hydrocarbon flows, taking into account heat exchange with the rocks surrounding the well, and phase transitions in the fluid. Using the software package, test calculations were carried out to demonstrate the performance of the proposed and implemented models.

PL

W artykule omówiono model matematyczny hydromechaniki przepływów wielofazowych o zmiennej masie. Przepływ wielofazowy jest traktowany jako kontinuum składające się ze zbioru dużej liczby różnych grup cząstek. Wprowadzone równania ruchu i kryteria podobieństwa są podane z uwzględnieniem zarówno zewnętrznej dołączonej (lub odłączonej) masy, jak i przejść fazowych wewnątrz ośrodka. Równania transferu masy, pędu i energii dla poszczególnych faz i ośrodka jako całości otrzymano przy użyciu podstawowych praw zachowania. Wykazano, że w przypadku braku źródeł (lub wypływów) masy, pędu i energii, znane równania hydromechaniki przepływu jedno- i wielofazowego wynikają jako szczególny przypadek z otrzymanych układów równań ruchu i kryteriów podobieństwa. Uzyskane równania ruchu mają zastosowanie do opisu składnika mieszaniny i medium jako całości, niezależnie od ich właściwości fizycznych i mechanicznych. Do ich rozwiązania można wykorzystać termodynamiczne i reologiczne równania stanu, a także wyrażenia dotyczące przepływu ciepła, siły międzyfazowych masy, przejść fazowych i wymiany ciepła między fazami. Wdrożone modele umożliwiają symulację zarówno stacjonarnego rozkładu parametrów wzdłuż odwiertu podczas wydobycia, jak i procesów niestacjonarnych, które zachodzą na przykład podczas zmiany prędkości wału pompy w trakcie wydobycia ropy. Opracowane podejścia zostały zaimplementowane w oprogramowaniu DataFlow do analizy hydrodynamiki wielofazowych przepływów węglowodorów, z uwzględnieniem wymiany ciepła ze skałami otaczającymi odwiert oraz przejść fazowych w płynie. Za pomocą pakietu oprogramowania przeprowadzono obliczenia testowe w celu wykazania wydajności proponowanych i wdrożonych modeli.

2

Water hummer in fluid networks

Osiadacz Andrzej J.

Gaz, Woda i Technika Sanitarna

|

2023

|

Nr 7-8

8--14

EN

The article discusses the problem of water hammer in fluid networks (gas, water supply and in pipelines transporting two-phase fluids. Mathematical models and selected computational algorithms are given.

PL

W artykule omówiono problem uderzenia hydraulicznego w sieciach płynowych (gazowych, wodociągowych oraz w rurociągach transportujących płyny dwufazowe. Podano modele matematyczne oraz wybrane algorytmy obliczeniowe.

3

Implementation of turbulence damping in the OpenFOAM multiphase flow solver interFoam

Polansky Jiri, Schmelter Sonja

Archives of Thermodynamics

|

2022

|

Vol. 43, no 1

21--43

EN

In the presented work Egorov’s approach (adding a source term to the ω-equation in the k-ω model, which mimics the damping of turbulence close to a solid wall) was implemented in on the subclass of shear stress transport models. Hence, turbulence damping is available for all shear stress transport type models, including hybrid models that are based on the ω-equation. It is shown that turbulence damping improves the prediction of the axial velocity profile not only for Reynolds-averaged Navier–Stokes simulation but also for detached eddy simulation and delayed detached eddy simulation models. Furthermore, it leads to a more realistic estimation of the pressure drop and, hence, to a more correct prediction of the liquid level. In this paper, simulation results for four different turbulence models are presented and validated by comparison with experimental data. Furthermore, the influence of the magnitude of the damping factor on the pressure drop in the channel is investigated for a variety of different gas-to-liquid flow rate ratios. These investigations show that higher gas-to-liquid flow rate ratios require higher damping factors to correctly predict the pressure drop. In the end, advice is formulated on how an appropriate damping factor can be determined for a specific test case.

4

Dynamics of bubble-particle interaction in different flotation processes and applications - a review of recent studies

Patnaik Nelesh, Menon Aditya, Gupta Tapesh, Joshi Vijesh

Physicochemical Problems of Mineral Processing

|

2020

|

Vol. 56, iss. 6

206--224

EN

Flotation process involves aggregation of the particles based on the material/compound type of random mixtures such as ores and seawater. It is primarily used in pretreatment of water desalination and other industrial applications. The process makes use of various fluid mechanics principles as multifluids are involved. The multi-fluids in most of the flotation processes are of different phases, such as air and water. Like any other process, the efficiency of flotation is important, and hence most of the studies have been dedicated to understanding how the various parameters are affecting the flotation process. Among various parameters, fluids properties and flow parameters chiefly affect the flotation process. In particular, the bubble-particle interaction of the flotation process has been of interest as it is one of the cost-effective ways to enhance flotation efficiency. In this review, the authors present the latest developments in such parametric studies. This paper could be of interest to research students, academic researchers, and practitioners who want to contribute to (or take from) flotation research.

5

Computational fluid dynamics modelling of short timebottle filling process

Jałowiecka Monika, Makowski Łukasz

Chemical and Process Engineering

|

2020

|

Vol. 41, nr 2

143-–163

EN

Every change in the bottle geometry as well as every change of physical and rheological properties posesa risk of excessive gas entrainment during a filling process. To maintain satisfactory filling efficiencythere is a need to optimise this process with respect to all adverse phenomena which affect the fluidflow, such as spluttering on the bottom, air caverns formation and air entrainment with incoming liquid.This paper comprises numerical simulations of two filling methods. The first method involves dosingwith a pipe placed over the free liquid surface of a fully filled bottle. The second method covers fillingwith a pipe located near the bottom. Moreover, the influence of rheological properties and surfacetension values is considered. The comprehensive analysis of amount of entrained air represented byair volume fraction in dispensed liquid let the authors define the influence of filling speed on themechanism and amount of entrapped air.

6

Numerical simulation of the stress state of an erosion-worn tee of the main gas pipeline

Doroshenko Ya., Zapukhliak V., Grudz Ya., Poberezhny L., Hrytsanchuk A., Popovych P., Shevchuk O.

Archives of Materials Science and Engineering

|

2020

|

Vol. 101, nr 2

63--78

EN

Purpose: To investigate the strength of tees with regard to their erosion wear, it is necessary to consider the complex three-dimensional geometric shape of the erosion worn inner surface of the tee. In addition, the study of the strength of the erosion worn tees of the main gas pipelines is complicated by the occurrence of additional stresses caused by changes in the direction of movement of the gas stream, resulting in an uneven pressure distribution in the inner cavity of the tee, and the temperature difference in its walls. Design/methodology/approach: Methodology for complex numerical three-dimensional simulation of the stressed state of tees of the main gas pipelines, taking into account the gas-dynamic processes that occur in the places of these defects, erosion wear of the tee wall, temperature difference in the tee walls. Findings: The acceptable parameters of erosion defects of tees of gas pipelines, and residual life of tees with erosion defects of the wall should be determined. Research limitations/implications: The developed model does not take into account internal corrosion and corrosion products as an additional erosion factor. Further studies plan to develop a model of corrosion-erosion wear of pipeline elements. Practical implications: The developed technique allows determining the location of erosion defects, estimating the strength and determining the residual life of tees with erosion wear of the wall in order to ensure their reliability, to rank such defects according to the degree of danger, to determine which of them are critical and need an immediate repair. Originality/value: Based on the gas-dynamic processes occurring in the internal cavity of the main gas pipelines’ tees, the complex three-dimensional geometric form of wall erosion defects, and temperature difference, the technique of three-dimensional simulation of stress state of the main gas pipelines’ tees is developed

7

Modelowanie procesu napełniania przy użyciu obliczeniowej mechaniki płynów

Makowski Ł., Wyszomierska E., Grochowiecki M.

Inżynieria i Aparatura Chemiczna

|

2018

|

Nr 4

102--103

PL

Celem pracy było przeprowadzenie symulacji procesu napełniania pojemników cieczami pieniącymi się o różnych właściwościach reologicznych oraz określenie wpływu tych właściwości na ułamek objętościowy powietrza w cieczy. Wykazano, że zgodnie z przewidywaniami największy wpływ ma lepkość oraz napięcie powierzchniowe płynu. Im niższa wartość napięcia powierzchniowego tym powstawała większa liczba pęcherzyków powietrza podczas procesu napełniania. Dla cieczy o dużej lepkości proces przebiegał odmiennie - zatrzymane powietrze w cieczy w trakcie procesu dużo wolniej zanika niż przy nalewaniu cieczy o małej lepkości.

EN

The aim of this work is to simulate the process of filling containers with foaming liquids with different rheological properties and to determ ine the effect of these properties on the volume fraction of air in the liquid. It has been shown that, as predicted, viscosity and surface tension of the fluid have the greatest influence. The lower the surface tension, the greater the number of air bubbles during the filling process. For viscous liquids the process is different - the air retained in the liquid during the process disappears much slower than when pouring Iow viscosity liquids.

8

Analiza sposobów modelowania reaktora trójfazowego ze stałym złożem (TBR) z użyciem metod CFD

Janecki D., Bartelmus G.

Inżynieria i Aparatura Chemiczna

|

2018

|

Nr 4

95--96

PL

Przedstawiono zagadnienia związane z zastosowaniem modelu wielofazowego Eulera do modelowania reaktora trójfazowego ze złożem stacjonarnym (TBR). Analizując równania modelu wyselekcjonowano parametry, które obliczane są w oparciu o dane dostępne w literaturze, a następnie przeprowadzono analizę czułości modelu na zmianę wartości wyselekcjonowanych parametrów. Przeanalizowano wpływ zmian zależności opisujących siły wzajemnych oddziaływań pomiędzy fazami oraz promieniowej zmiany porowatości wypełnienia na wyniki obliczeń numerycznych.

EN

The paper presents issues connected with the use of Eulerian multiphase model for modelling a three-phase fixed-bed reactor (TBR). Param eters calculated on the basis of available in literature data were selected, and next the analysis of model sensitivity to the change of selected parameters was carried out. The influence of changes of relationships describing the interaction forces between phases and the change of radial porosity of packing on the results of numerical calculations was analyzed.

9

Zastosowanie metody kratowego równania Boltzmanna do modelowania w metalurgii i inżynierii materiałowej

Svyetlichnyy D., Straka R., Łach Ł.

Hutnik, Wiadomości Hutnicze

|

2018

|

Vol. 85, nr 4

141--151

PL

W pracy przedstawiono podstawowe wiadomości o metodzie do modelowania matematycznego procesów i zjawisk zawierających przepływ gazu i cieczy nazywanej Lattice Boltzmann Method (LBM - Metoda kratowego równania Boltzmanna). Trzema głównymi kierunkami stosowania LBM w opracowaniach autorów są: przepływ cieczy o swobodnej powierzchni z uwzględnieniem wymiany ciepła i przemiany stanu skupienia; ciągły przepływ cieczy i gazu; przemiany fazowe. W pracy przedstawiono wyniki modelowania oraz zastosowania metody do modelowania procesów przemysłowych i jej wykorzystanie w procesie dydaktycznym. Zwrócono uwagę na przewagi opisywanej metody oraz duże możliwości przyspieszenia obliczeń poprzez ich zrównoleglenie na współczesnych procesorach graficznych (GPU - graphics processing unit) .

EN

The basic information about the Lattice Boltzmann Method (LBM), used for numerical modeling of the processes and phenomena contained fluid flow, is presented in the paper. Three main direction of application of the LBM developed and described by the authors are: fluid flow with free surface, taking into account conductive heat transfer and changes of state of matter; continuous fluid flow; and phase transformations. Results of simulations by LBM as well as its application to industrial processes and for teaching are presented in the paper. Attention is paid to advantages of the method and possibility to accelerate its calculations through their parallelization on modern graphics processing units (GPUs).

10

Przepływ pierścieniowy mieszaniny wielofazowej gaz-ciecz-ciecz w rurach aparatów cienkowarstewkowych

Brandt A., Czernek K., Pietrzak M., Płaczek M., Witczak S.

Przemysł Chemiczny

|

2017

|

T. 96, nr 3

598--603

PL

Przedstawiono wyniki badań hydrodynamiki pierścieniowego, opadającego w rurze pionowej przepływu wielofazowego gazu i dwóch wzajemnie niemieszających się cieczy. W wyniku analizy danych doświadczalnych wyznaczono obszary występowania określonych struktur przepływu na nowo opracowanej mapie przepływu, słusznej zarówno dla przepływu dwufazowego ciecz-ciecz, jak i dla przepływu trójfazowego gaz-ciecz-ciecz. Opracowano także równania opisujące wpływ wybranych parametrów przepływowych oraz właściwości faz na uzyskiwanie określonych wartości grubości filmów cieczy.

EN

Hydrodynamics of annular falling flow of gas and 2 immiscible liqs. in vertical pipe was studied. The new flow pattern map valid for both liq.-liq. 2-phase flow and gas-liq.-liq. 3-phase flow were developed. The effects of flow parameters and phase properties on the liq. film thicknesin the flow systems were approximated with resp. equations.

11

LES numerical study on in–injector cavitating flow

Pyszczek R., Kapusta Ł. J., Teodorczyk A.

Journal of Power Technologies

|

2017

|

Vol. 97, nr 1

52--60

EN

In this paper a computational study on hexane flow in a fuel injector is presented. Large Eddy Simulation (LES) was used to capture the turbulent patterns present in the flow. The main aim was to investigate the cavitation phenomenon and its interaction with turbulence as well as the influence of injection pressure and backpressure on fuel mass flow and flow conditions. Analysis of the approach to define the outlet boundary conditions in terms of convergence time and fluid mass outflow oscillations formed a crucial part of the study. Numerical simulations were performed with AVL Fire CFD (Computational Fluid Dynamics) software. The Euler-Euler approach and multifluid model for multiphase flow modelling were applied. Injector needle movement was included in the simulation. Results show that the additional volumes attached to the nozzle outlets improved the convergence of the simulations and reduced mass outflow oscillations. Fuel mass flow at the outlets was dependent on inlet pressure, position of the needle and backpressure, while the influence of backpressure on fuel mass flow was negligible. The presence of the vapor phase at the exit of the nozzles did not affect average fuel mass flow. All the simulations showed interaction between the gaseous phase distribution and the turbulence of the flow.

12

Predicting relative permeability from experimental capillary pressure porous plate test for two phase flow

Czarnota R., Janiga D., Stopa J., Wojnarowski P.

AGH Drilling, Oil, Gas

|

2017

|

Vol. 34, no. 2

323--334

EN

Relative permeabilities relationships as a function of fluids saturation are one of the most important parameters for describing multiphase flow processes in reservoir rocks. When direct laboratory tests are not available for investigating oil-water multi-phase flow in rocks, then indirect prediction techniques using relative permeability functions are widely used, e.g. from capillary pressure test. In this study the measurement of capillary pressure was performed on rocks plugs with different characteristics at reservoir conditions using porous plate method. During measurement semi-permeable membrane was used with 15 bar threshold pressure, what allowed to register formation water saturation, at changing differential pressures steps. Desaturation at each pressure stage was continued until no more produced liquid was observed. Water saturation point at maximum capillary pressure applied is assumed to be final irreducible water saturation. Application of porous plate method provides sufficient stabilization time, allowing to achieve uniform saturation distribution. In this research, Brook-Corey model was used to predict relative permeability from experimental measured capillary pressure data for oil-water phase flow in porous media. As a result, it is possible to obtain more accurate capillary pressure outcomes, and relative permeability curves for the two-phase system, than other methods used in practice. Performing capillary pressure measurements at reservoir conditions, allows to restore the processes occurring in the reservoir.

13

Influence of emulsion inner phase concentration on permeability of deposit during flow through porous media

Przybysz Ł., Błaszczyk M., Sęk J.

Acta Innovations

|

2017

|

no. 23

25--34

EN

The issue of emulsion flow through porous media plays an important role in the development of land purification methods from various oily substances, as well as during the oil extraction process. The concentration of the emulsion dispersed phase exerts a strong influence on the rheological properties. The oil in water emulsions (O/W), that have a concentration of less than 0.5 (or 50%), show Newtonian behavior, and those with higher concentrations non-Newtonian. The flow of such systems through the structure of the porous medium is, therefore, also dependent on the variable rheological properties of the liquid. When the emulsion flows through the porous medium, a reduction of the relative permeability occurs. Due to that the transport may be very effectively limited, as the pores of deposit are being blocked by oil droplets. The paper presents studies on emulsion flow, with various concentrations, through a granular bed. It allowed to track changes in the permeability of the deposit over time. The results of experimental studies of transport and elution of highly concentrated emulsions from granular structures are also presented. This enabled tracking of changes in flow resistance of the emulsion through the porous bed in time. Moreover, the development of the mathematical model, which allows us to define the relationship between the bed blockage degree and the concentration of the emulsion internal phase could be the result of the experimental works. The results of such studies are very widely used in practice, among other things, in the issues of migration of pollutants, such as petroleum substances, in the soil layers. The development of knowledge in this field may contribute to the optimization of existing oil recovery techniques and methods of remediation of soil from organic substances.

14

Zmniejszanie erozji w hydrocyklonach za pomocą specjalnych dodatków

Malcher T.

Przemysł Chemiczny

|

2016

|

T. 95, nr 8

1510--1512

PL

Wykonano dwie symulacje numeryczne przepływu układu wielofazowego przez hydrocyklon. W pierwszej symulacji fazą ciągłą była woda a fazą stałą były ziarna piasku. W drugiej zamiast wody zastosowano wodny roztwór specjalnych dodatków zmniejszających opory przepływu. Celem obu symulacji było znalezienie takich regionów, w których erozja jest największa. Erozja wywołana przepływem roztworu i cząstek stałych była mniejsza od erozji wywołanej przepływem wody i cząstek stałych.

EN

Multiphase water-sand and aq. soln.-sand flows through a hydrocyclone was numerically simulated to det. the regions with the highest erosion. The aq. soln. contained poly(ethylene oxide) 30 ppm, C₁₆H₃₃Me₃NBr 2 mM and Na salicylate 2 mM. The addn. of drag-reducing agents resulted in decreasing the hydrocyclone erosion.

15

Transport emulsji typu olej w wodzie przez struktury ziarniste

Błaszczyk M., Sęk J., Przybysz Ł.

Inżynieria i Aparatura Chemiczna

|

2016

|

Nr 1

8--9

PL

W pracy przedstawiono badania przepływów emulsji typu olej w wodzie przez złoża ziarniste oraz jej wymywania ze złoża za pomocą wody. Mierzono zmiany oporów przepływu podczas przemieszania się tych płynów przez media ziarniste oraz zmiany struktury emulsji wypływającej ze złoża w czasie trwania procesu i analizowano wpływ stężenia fazy wewnętrznej, stopnia granulacji złoża oraz jego długości. Stwierdzono stopniowy spadek przepuszczalności, czasową redukcję stężenia fazy olejowej oraz zmiany rozkładu rozmiarów kropel wypływającej ze złoża emulsji. Wyniki badań mogą przyczynić się do bardziej precyzyjnej oceny efektywności zarówno wtórnych metod wydobycia ropy jak i remediacji gleb.

EN

The paper presents studies of oil-in-water emulsions flow through granular media and the studies of elution of these liquids from the bed with the use of water. The changes in flow resistance during the movement of such fluids through granular media and changes in the structure of emulsion flowing out from the reservoir during the process were measured and the influence of internal phase concentration, degree of bed granulation and its length were analyzed. A gradual decrease in permeability, temporary reduction of oil phase concentration and changes in the distribution of droplets sizes in emulsion flowing out of the bed was recorded. The research results may contribute to more accurate evaluation of effectiveness of secondary oil recovery methods and soil remediation.

16

Dynamics of particle loading in deep-bed filter. Trasport, deposition and reentrainment

Przekop R., Gradoń L.

Chemical and Process Engineering

|

2016

|

Vol. 37, nr 3

405--417

EN

Deep bed filtration is an effective method of submicron and micron particle removal from the fluid stream. There is an extensive body of literature regarding particle deposition in filters, often using the classical continuum approach. However, the approach is not convenient for studying the influence of particle deposition on filter performance (filtration efficiency, pressure drop) when non-steady state boundary conditions have to be introduced. For the purposes of this work the lattice-Boltzmann model describes fluid dynamics, while the solid particle motion is modeled by the Brownian dynamics. For aggregates the effect of their structure on displacement is taken into account. The possibility of particles rebound from the surface of collector or reentrainment of deposits to fluid stream is calculated by energy balanced oscillatory model derived from adhesion theory. The results show the evolution of filtration efficiency and pressure drop of filters with different internal structure described by the size of pores. The size of resuspended aggregates and volume distribution of deposits in filter were also analyzed. The model enables prediction of dynamic filter behavior. It can be a very useful tool for designing filter structures which optimize maximum lifetime with the acceptable values of filtration efficiency and pressure drop.

17

Hydrodynamics of Pilot Plant Scale Airlift Reactor in Presence of Alcohols

Nandi S., Jaju S. J.

Polish Journal of Chemical Technology

|

2015

|

Vol. 17, nr 3

118--123

EN

The overall gas hold-up of a pilot plant scale internal loop airlift reactor was studied in presence of different alcohols in varied concentration. It has been observed that these simple alcohols can enhance overall gas hold-up of the airlift assembly possibly due to formation of protective thin layer over smaller gas bubbles thereby reducing chance of their coalescence. As the alcohols can be used as food source for the micro organisms present in the system, this green and environment friendly process have potential to replace usage of hazardous surfactants often used for enhancing overall hold-up in order to obtain desired mass transfer characteristics. An empirical relationship encompassing overall gas hold-up of the reactor as a function of superficial gas velocity and alcohol concentration is also developed.

18

Modelowanie kawitacji przy opływie profilu z zastosowaniem zmiennej liczby kawitacji

Homa D., Wróblewski W.

Modelowanie Inżynierskie

|

2015

|

T. 24, nr 55

42--49

PL

W artykule przedstawiono modelowanie przepływu z kawitacją w przypadku opływu wokół profilu hydraulicznego. Liczba kawitacja została dobrana w taki sposób, by zaobserwować różne typy struktur kawitacyjnych. Użyto modelu wielofazowego typu one–fluid oraz założono izotermiczność przepływu. Do zamodelowania powstawania fazy gazowej użyto modelu Schnerr & Sauer. Ze względu na niestacjonarność zjawiska zastosowano symulacje typu transient. Porównano wyniki symulacji z danymi eksperymentalnymi dla różnych typów kawitacji. Przeanalizowano rozkłady udziału objętościowego pary w punktach monitorujących wzdłuż profilu oraz okresy zmian struktur kawitacyjnych. Do symulacji użyto profilu ClarkY. Obliczenia przeprowadzono z użyciem kodu OpenFoam z wykorzystaniem solvera interPhaseChangeFoam.

EN

The paper concerns cavitation modelling in case of flow over a hydrofoil. Cavitation number was set to the values that enable to observe different types of cavitation. Multiphase model of one-fluid type was used and isothermal flow was assumed. To simulate vapor volume transport the Schnerr & Sauer model was used. As the investigated phenomenon is unsteady transient type of calculation was used. The calculation results for different cavitation types were compared with the available experimental data. The distribution of vapor volume fraction in monitor points over the foil as well as changes in the frequency of cavitation structures were analysed. The simulation was run on ClarkY foil. The calculations were performed using OpenFoam open source code with interPhaseChangeFoam solver.

19

Efekt odparowania fazy ciekłej na fali uderzeniowej w przepływach okołodźwiękowych powietrza wilgotnego z kondensacją pary wodnej

Szymański A., Dykas S., Majkut M.

Modelowanie Inżynierskie

|

2015

|

T. 26, nr 57

54--62

PL

W pracy przeprowadzono analizę numeryczną przepływu transonicznego powietrza atmosferycznego, które ze swojej natury zawsze zawiera pewną ilość pary wodnej, w dyszach de Lavala. Do obliczeń wybrano dyszę de Lavala o dużej prędkości ekspansji i połówkową dyszę zbieżno-rozbieżną o znacznie mniejszej prędkości ekspansji. Obliczenia przeprowadzono za pomocą własnego kodu CFD, w którym zamodelowano powstawanie fazy ciekłej w wyniku kondesacji spontanicznej pary wodnej zawartej w powietrzu wilgotnym. W obliczeniach przepływu okołodźwiękowego uwzględniono również obecność prostopadłej fali uderzeniowej w części naddźwiękowej dyszy w celu analizy efektu odparowani fazy ciekłej.

EN

This paper presents a numerical analysis of the atmospheric air transonic flow through de Laval nozzles. By nature, atmospheric air always contains a certain amount of water vapour. The calculations were made using a Laval nozzle with a high expansion rate and a convergent-divergent (CD) “half-nozzle”, referred to as a transonic diffuser, with a much slower expansion rate. The calculations were performed using an in-house CFD code. The computational model made it possible to simulate the formation of the liquid phase due to spontaneous condensation of water vapour contained in moist air. The transonic flow calculations also take account of the presence of a normal shock wave in the nozzle supersonic part to analyse the effect of the liquid phase evaporation.

20

Advancements in centrifugal compressor development for challenging applications

Biba Y., Koch J., Maier W.

Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka

|

2014

|

nr 146

45--46

EN

The lecture provides an overview of challenging compressor applications (in terms of common aerodynamic criteria) focusing on two examples, due to their use of advanced analytical tools and test models. Development of DATUM ICS with Rotating Centrifugal Separator (RCS) technology combined rotary gas-liquid separation and centrifugal compressor flow path. Such a combination represents a new class of turbomachinery and leads to increased system compactness by significantly reducing the size and weight of installed equipment and eliminating large separation vessels often used on traditional compressor trains. An overview is given for the Dresser-Rand RCS development, multiphase mean-line and CFD modeling, and Demo tests, including the latest one at high pressure conditions, more challenging for separation. The test allowed better understanding of the aero- and thermodynamic behavior of the RCS and validated both compression and separation performance at demanding operating conditions. Centrifugal compressors in the refrigeration cycles of LNG production process are characterized by large flow coefficient and high machine Mach number. Therefore both compressed medium and high speed operation directly impact performance. An overview is given on a typical CFD analysis of high-Mach number application stage, along with its test validation on D-R development test rig. Discussion on optimization highlights both the mean-line level of design and analysis, when specialized tools are used for preliminary design, and the CFD level, through parametric studies.