ENCIT2012-110 NUMERICAL SIMULATION OF THE TWO-PHASE FLOW USING FOURIER-SPECTRAL METHOD - PDF
Mariana Fernandes dos Santos Villela, UFU, Brazil
Felipe Pamplona Mariano, UFG, Brazil
Aristeu da Silveira Neto, UFU, Brazil
Abstract: In DNS, are simulation of two-phases flows, the high level of refinement is required when details and physical discontinuity are desired studied. Required is also low computational cost due to simulations intended type of problem need high mesh refinament or have a large estencil discretization, wich makes them computacionally expensive. Once two-phase flows simulations require a high level of mesh refinement and/or methods based on large stencil discretizations, the search for high order methods with comparatively low computational cost is mandatory. In the present work, a new, hybrid Fourier pseudo-spectral methodology - Front tracking/Front capturing methods is presented for numerical simulation two phase-flow with non periodic boundary condition. Results for the rise cylindrical bubble are presented.
Keywords:Two-phase flow; Front-Tracking/Front-Capturing; Fourier pseudo-spectral method.
Presentation Schedule: Tuesday, 14:40-15:00. Session: FMR3-1. Presenter: Mariana Fernandes dos Santos Villela.
ENCIT2012-122 EFFECTS OF THE GRANULAR MOBILITY ON A TURBULENT FLOW - PDF
Fabíola Tocchini de Figueiredo, Eugênio Spanó Rosa, Unicamp, Brazil
Erick de Moraes Franklin, FEI, Brazil
Abstract: The transport of granular matter by a fluid flow is frequently found in nature and in industry.The presence of bed-load, a mobile granular layer which is in contact with the fixed part of the bed, may affect the turbulent liquid flow. This phenomenon is known as feed-back effect. The experiments were performed on a closed-conduit channel of rectangular cross section where the grains were transported as bed-load. The employed fluid was water and was used the a PIV (Particle Image Velocimetry) device was employed to measure the turbulent liquid flow. The turbulent fully-developed velocity profiles over fixed and mobile granular beds were measured for two differents diameters of grains, 160 \&\#956;m and 360 \&\#956;m, for roughly the same water flow rates, in conditions near the threshold of the bed-load. The fluctuations profiles were obtained in order to obtain the effects of bed-load on the turbulent flow.
Keywords:feed-back effect; sediment transport; bed-load.
Presentation Schedule: NO PRESENTATION.
ENCIT2012-173 THERMAL ANALYSIS OF 1D TWO PHASE FLOW IN A HORIZONTAL PIPE USING THE TWO-FLUID MODEL - PDF
Eugenio F. Simões, PUC-Rio, Brazil
João N. E. Carneiro, SINTEF Brasil, Brazil
Angela Ourivio Nieckele, PUC-Rio, Brazil
Abstract: In this work, a non-isothermal intermittent air-water two phase flow in a circular pipe is studied. A 1D slugcapturing code based on the two-fluid formulation was extended to include thermal effects. Simulation results are compared with experimental data and the impact of the boundary conditions in the results are presented. An evaluation of the pipe length upstream of the heat transfer test section and the introduction of a white noise signal in the thermal and hydrodynamic parameters are conducted. The predicted pressure and temperature drop presented a reasonable agreement with the experimental data. Furthermore, it was shown that it is possible to use a white noise signal to shorten the required pipe length, thus reducing the computational domain and reducing the computational power required.
Keywords:thermal analysis; 1D; horizontal pipe; two-fluid model.
Presentation Schedule: Tuesday, 15:00-15:20. Session: FMR3-1. Presenter: Eugenio F. Simões.
ENCIT2012-282 REVISITING THE LIQUID FLUIDIZED BED LAYER INVERSION PHENOMENA WITH COMPUTATIONAL FLUID DYNAMICS - PDF
Alexandre M S Costa, Jean R Bocca, Paulo R. Paraiso, Luiz M M Jorge, UEM, Brazil
Abstract: Solids mixing and segregation happens in liquid fluidized beds containing binary mixtures differing by density and size. The solid layer inversion occurs in a binary mixture when solids with greater size and smaller density reverse their relative vertical position, i.e. goes to the bottom, in the bed as the liquid velocity is increased In this work, we revisit the methodology of Syamlal and O´Brien (1988) using CFD and based on the Moritomi et al.(1982). experiments. The goal of our work is to compare the capabilities of new CFD models for polidisperse systems available in the literature in predicting and accurately describing aspects of the inversion phenomenon.
Keywords:fluidized beds; computational fluid dynamics; MFIX.
Presentation Schedule: Tuesday, 14:20-14:40. Session: FMR3-1. Presenter: Alexandre M S Costa.
ENCIT2012-307 EXPERIMENTAL CHARACTERIZATION OF THE FLOW FIELD AND OIL DROPLET DISTRIBUTION ACROSS A CYCLONIC VALVE - PDF
Carolina Azevedo Fernandes, Ricardo Fernandes Ribeiro, Juliana Braga Rodrigues Loureiro, Atila Pantaleão Silva Freire, UFRJ, Brazil
Abstract: The purpose of the present work is to evaluate the performance of a cyclone-based valve in improving the separation efficiency of a two-phase oil-water mixture. This valve has been observed to have beneficial effects on the formation of oil drops in the outlet. The present work identifies the basic mechanisms of drop break up and relates them to the actual geometry of the valve. The experiments used water as the working fluid and model oil as the dispersed phase. Measurements of droplet size distribution are performed with the aid of two different techniques: Focused Beam Reflectance Measurement (FBRM) and a Shadow Sizer (SS) system. These techniques are complementary and allow measurements from 0.3 micron to the milimeter range.
Keywords:Turbulence; Oil-droplet size; Oil-water separation; Experimental measurements.
Presentation Schedule: Tuesday, 17:20-17:40. Session: FMR3-2. Presenter: Carolina Azevedo.
ENCIT2012-376 INVESTIGATION OF CLOSURE RELATIONS FOR 1D TWO-FLUID MODEL IN VERTICAL PIPES - PDF
Jerry da Ressureição Geraldo Inacio, Angela Ourivio Nieckele, PUC-Rio, Brazil
João N. E. Carneiro, SINTEF Brasil, Brazil
Abstract: The 1D Two-Fluid Model is based on the time and pipe cross-section area averages of the transport equations governing the flow, requiring the inclusion of closure parameters for the gas and liquid phases. The closure relations must be able to realistically represent the physical phenomenon of interest, and the resulting set of governing equations must also be well-posed. At the present paper, two closure relations are considered to render a well posed set of conservation equations to predict the upward slug flow in vertical pipes. These parameters are: pressure jump due to the curvature of the interface, and a momentum flux parameter. Main characteristics for statistically steady flow regime are compared with experimental data presenting good agreement. It is shown that the inclusion of a constant momentum flux parameter for the liquid phase plays a more significant role than the pressure jump to improve well-posedness in vertical flows.
Keywords:Two phase flow; vertical pipe; 1D; Two - Fluid Model; Closure Parameter.
Presentation Schedule: Wednesday, 16:40-17:00. Session: OPO-1. Presenter: Jerry da Ressureicao Geraldo Inacio.
ENCIT2012-184 SLUG TO CHURN TRANSITION ANALYSIS IN UPWARD VERTICAL TWO-PHASE FLOW - PDF
Arthur F. Gomes, Andrea E. Nakayama, Cristiane Cozin, Fausto A. A. Barbuto, Rigoberto E. M. Morales, UTFPR, Brazil
Abstract: The prediction of gas-liquid two-phase flow patterns is still an unresolved issue and has been the focus of study of a large number of authors. The efforts were directed towards the development of physical models that allow the analytical prediction of the flow patterns and their transition boundaries. Several models to delineate the slug-to-churn flow transition have been suggested, due to the relevance of the aforementioned transition to many engineering enterprises, as it is the case of the petroleum and the chemical industries. However, there is a lot of uncertainty over the most accurate model to predict the slug-to-churn flow transition, mainly because of the subjective methods adopted by each author to identify the slug and churn flow patterns, and also because of the difficulty in modeling this chaotic transition. The present work aims at analysing some existing models to predict the slug-to-churn flow transitions. The performances of these models were evaluated and compared to experimental data for different flow conditions.
Keywords:Gas-liquid flow; flow pattern; slug flow; churn flow.
Presentation Schedule: Tuesday, 17:00-17:20. Session: FMR3-2. Presenter: Rigoberto Morales.
ENCIT2012-188 NUMERICAL SIMULATION OF HEAT TRANSFER IN TWO-PHASE SLUG FLOW USING A SLUG TRACKING METHOD - PDF
César D. P. Medina, Carlos L. Bassani, Cristiane Cozin, Silvio L. M. Junqueira, Rigoberto E. M. Morales, UTFPR, Brazil
Abstract: In the present work, the numerical simulation of heat transfer in non-boiling two-phase slug flow is developed for horizontal pipes. The slug flow pattern is characterized by the alternate succession of two structures: an aerated liquid slug and an elongated gas bubble, which constitute a unit cell. This concept is used by the slug tracking models in order to develop a lagrangian model in transient regime, capable of accurately predicting the flow behavior with low computational time. However, slug tracking models are generally developed to predict hydrodynamic parameters only, ignoring heat transfer. Present work couples the heat transfer governing equations with the slug tracking model through energy balances in deformable and moving control volumes using the Reynolds transport theorem in its integral form. In addition, a new expression for the calculation of the two-phase heat transfer coefficient is proposed. A good agreement between the numerical results and data from the literature was found.
Keywords:two-phase flow; intermittent flow; convection; heat transfer.
Presentation Schedule: Tuesday, 15:40-16:00. Session: FMR3-1. Presenter: Rigoberto Morales.
ENCIT2012-186 NUMERICAL SIMULATION OF SLIGHT DIRECTION CHANGES IN TWO-PHASE FLOWS USING A SLUG TRACKING MODEL - PDF
Carlos L. Bassani, Marco G. Conte, Victor E. L. Parra, César D. P. Medina, Cristiane Cozin, Fausto A. A. Barbuto, Rigoberto E. M. Morales, UTFPR, Brazil
Abstract: Slug flows occur in many industrial applications such as the transportation of oil and natural gas in a pipeline. The slug flow pattern is characterized by intermittent liquid slugs and elongated bubbles, whose lengths and velocities change in space and time. Hilly terrains influence flow parameters due to slight direction changes on the bottom of the sea, making slugs to grow or generating new ones. These changes affect the pressure drops and are paramount in the design of production facilities. The present work introduces a mathematical model for the liquid accumulation due to horizontal-to-slightly inclined direction changes, analyzing only the slug growth. The aforementioned model attempts to describe the phase fraction changes in the liquid slug and in the elongated bubble and is coupled to a lagrangian slug tracking model for the prediction of hydrodynamic parameters. The results were compared to experimental data, and a good agreement has been obtained.
Keywords:two-phase flow; intermittent flow; hilly terrain; slug tracking.
Presentation Schedule: Tuesday, 16:00-16:20. Session: FMR3-1. Presenter: Victor E. L. Parra.
ENCIT2012-094 CHARACTERISATION OF AIR-WATER SLUG FLOW USING FIBER BRAGG GRATING SENSOR - PDF
Virgínia Helena Varotto Baroncini, Eduardo Nunes Santos, Rodolfo Luiz Patyk, Maura Scandelari Milczews, Cícero Martelli, Carlos Eduardo Ferrante Amaral, Marco da Silva, Cristiane Cozin, Rigoberto Eleazar Morales, UTFPR, Brazil
Abstract: This paper describes a new technique using fiber Bragg grating fiber, applied to the problem of measuring two-phase. The development of techniques for measuring two-phase flow with high performance, precision and safety has stimulated the search for new methods and monitoring instrumentation. Experimental tests were made in flow testing, where various operating conditions were generated and analyzed. The new develop technique has been agreed through comparisons with mechanical models available empirical literature and with software for data processing of wire-mesh sensor, showing good agreement with reference values.
Keywords:fiber bragg grating sensor; wire- mesh; slug flow; two-phase flow.
Presentation Schedule: Tuesday, 15:20-15:40. Session: FMR3-1. Presenter: Virgínia Helena Varotto Baroncini.