ENCIT2012-004 DESIGN OF A CENTRIFUGAL COMPRESSOR FOR NATURAL GAS - PDF
Sandro Kojiro Kurauchi, João Roberto Barbosa, ITA, Brazil
Abstract: This work presents the design of a centrifugal compressor for natural gas in three steps. The first step is the 1-D preliminary design heavily based on empirical data, only the design point was considered here. The second step is the flow analysis in the meridional plane. The last step is the CFD analysis to verify if the 1-D design methodology is adequate. The CFD simulations showed good agreeiment with the results obtained in the preliminary design, proving the importance of empirical data in the design of centrifugal compressors.
Keywords:centrifugal compressor; CFD; turbomachinery.
Presentation Schedule: Thursday, 15:20-15:40. Session: FMR6-2. Presenter: João Roberto Barbosa.
ENCIT2012-175 ONE-DIMENSIONAL PRELIMINARY COMPRESSOR DESIGN APPLIED TO A 500 KW GAS TURBINE AND THE EFFECT OF BLADE NUMBER - PDF
André Perpignan Viviani de Campos, Guenther Carlos Krieger Filho, USP, Brazil
Abstract: This work presents the thermodynamic cycle calculation for a 500 kW gas turbine and its first design choices to introduce the preliminary compressor design. The radial type compressor selection through charts involving the similitude principle is described. A one-dimensional impeller design procedure based on basic fluid mechanics and thermodynamics, as well as on empirical correlations, was implemented to provide the impeller main dimensions. As available correlations for the impeller number of blades are not conclusive, CFD was used to evaluate the performance and efficiency of the impeller with the designed blade in different numbers. Using the CFX solver with the RNG k-\&\#949; turbulence model, the design point was reproduced for various blade numbers. Simulations were able to capture the raise and subsequent decrease in efficiency while the blade number was increased, characterizing an optimum point among friction and slip losses. In the range of blade number from 10 to 30, efficiency varies almost 10\%, proving that a wise blade number selection is crucial for the whole gas turbine performance.
Keywords:impeller design; centrifugal compressor; empirical correlations.
Presentation Schedule: Thursday, 14:20-14:40. Session: FMR6-2. Presenter: André Perpignan Viviani de Campos.
ENCIT2012-053 AN AXIAL-FLOW TURBINE PERFORMANCE CALCULATIONS BASED ON CFD TECHNIQUES - PDF
Luiz Müller, Jesuino Takachi Tomita, ITA, Brazil
Abstract: A single-stage axial-flow turbine was designed using the meanline approach with the addition of loss models and its 3D geometry was generated to become possible the study and its performance evaluation using CFD techniques. A specialized turbomachine commercial software was used for preliminary design and flow calculations. The three-dimensional turbulent flow calculations was performed based on a 3D CFD software with RANS formulations and the turbine operation map was determined. The results from CFD software were compared with the meanline turbine data including its performance map. The mesh generation processes and numerical issues are discussed and the CFD results are presented based on the fluid properties distribuiton along the blade span (NGV and rotor). The turbine shaft work and its efficiency for several operation points also are calculated and compared.
Keywords:turbomachines; CFD; axial turbine; computational grids; gas turbine.
Presentation Schedule: Wednesday, 09:40-10:00. Session: FMR6-1. Presenter: Luiz Müller.
ENCIT2012-058 OPTIMIZATION OF SUCTION TUBE BY USING PLAN OF EXPERIMENTS AND CFD TECHNIQUES - PDF
Tássio Rezende, Edna R. da Silva, Ramiro Gustavo Ramirez Camacho, FEI, Brazil
Abstract: In the developing of the design of flow machines and their components, one of the biggest challenges for the designer, in the incessant quest for increasing efficiency of turbomachinery, is to obtain an optimal geometry for the spiral case, runner, distributor and draft tube. In the first projects of hydraulic turbines, the experience of engineers and designers, along with numerous and costly tests with scale models, many of which are conducted on a "trial and error" basis, were the main design tools available. Part of this empirical knowledge accumulated was condensed into diagrams and guides (still used today), which provide good guidelines for pre-sizing for turbine draft tubes. Another part of this technology was retained with manufacturers as a legacy to future teams of engineers from the companies. Currently, the design of hydraulic turbines(rotor and draft tube) is made with increasingly intense use of computer programs for numerical calculation of the flow through the machine. These tools, like CFD (Computational Fluid Dynamics), are able to simulate accurately many important phenomena that occurs in the flow inside the turbine or the draft tub, helping the engineer understand these hydraulic passages details. Only after exhaustive investigations the reduced model is build to final tests at laboratories. The total time and costs spent on development of a new design is significantly reduced with this methodology, based in generation plane of experiments (DOE), heuristic optimization and metamodels construction. This paper aims propose a method of optimization for reduce the loss coefficient in the suction tube, from the construction of design of experiments(DOE)
Keywords:Draft Tubes; Optimization; CFD; DOE.
Presentation Schedule: Thursday, 16:00-16:20. Session: FMR6-2. Presenter: Ramiro G. Ramirez Camacho.
ENCIT2012-196 STEAM TURBINE CASCADE OPTIMIZATION USING CONTROLLED RANDOM SEARCH ALGORITHM AND CFD TECHNIQUES FOR ORC APPLICATION - PDF
Oliver J. Visconti, Ramiro Gustavo Ramirez Camacho, Willmari D. Suarez, FEI, Brazil
Abstract: This paper presents a methodology for performance optimization of a steam turbine cascade using controlled random search algorithm and CFD techniques for ORC (Organic Rankine Cycle) application. The steam turbine cascade is parameterized to achieve the maximum efficiency while using differents organics fluids. The main objective of this work is to attain the maximization Cl /Cd ratio from a preliminary design. The approach to find the maximum Cl/Cd ratio is based in optimization algorithms. The controlled random search algorithm (CRSA) was chosen for the optimization process. The otimization algorithm CRSA is integrated with CFD techniques, using schemes automatic building of parameterized geometries and meshes via "script files" with editing commands written in Tlc/Tk language, wich will be interpreted by the commercial software ICEM-CFD®, in batch mode. Finally, for the numerical calculation, the commercial software FLUENT® is used with fluids properties, real gases model, turbulence model and boundary conditions set through "journal files". In this paper, R245fa and Toluene are used as working fluids. Results of drag, lift and pressure distribution are reported. This metodology allows making corrections in the initial project of the cascade shape without using a lot of computational effort.
Keywords:ORC; optimization; CFD techniques; CRSA.
Presentation Schedule: Wednesday, 10:20-10:40. Session: FMR6-1. Presenter: Oliver José Visconti Montero.
ENCIT2012-223 EVALUATION OF PRESSURE DROP IN FLOW OVER FIXED POROUS BED - PDF
Roger Barros da Cruz, Danielle Regina da Silva Guerra, Tamires Lopes de Azevedo, UFPA, Brazil
Abstract: Many studies are conducted about the dynamics of fluids in porous media, which generates a number of factors. In particular the phenomenon of pressure drop in flows over a fixed bed, although fairly well in the form of the Ergun equation, still has certain inconsistencies with regard to the types of materials to be employed in the packaging of the beds. The objective of this work is to study this phenomenon using some experiments reported in the literature to determine the pressure drop in fixed bed consisting of porous particles of açaí seeds. Experimental studies were performed to predict, being taken into account losses resulting from friction and inertia which showed a strong dependence on speed.
Keywords:pressure drop; fixed bed; bed porosity; açaí's seeds.
Presentation Schedule: Tuesday, 18:00-18:20. Session: FMR3-2. Presenter: Roger Barros da Cruz.
ENCIT2012-340 EXPERIMENTAL FLOW MEASUREMENT WITH INTEGRAL ORIFICE - PDF
Marcelo Filardi, Smar Equip. Ind. Ltda, Brazil
Edson Del Rio Vieira, Sérgio Said Mansur, UNESP, Brazil
Abstract: Abstract. Integral orifice is an industrial flowmeter useful for small diameter lines (typically up to 38 mm) and provides a very precise alignment necessary to small diameter lines. In the present work have been performed out several experiments using integral orifices in 12.7 mm PVC pipes checking the influence of the tube roughness, the eccentricity of the hole and orifice geometry in the flow measurements. The discharge coefficients have been obtained in function of the Reynolds number. Results show concentric plates with square edge permit operation in a wide Reynolds range allied a cheaper manufacturing process and a good accuracy.
Keywords:Integral orifice; Discharge Coeffcient; Flow measurement; Flowmeter.
Presentation Schedule: Thursday, 15:00-15:20. Session: FMR6-2. Presenter: Edson Del Rio Vieira.
ENCIT2012-220 EXPERIMENTAL AND NUMERICAL STUDY OF THE VELOCITY PROFILE IN A CONICAL DIFFUSER APPLIED TO WIND TURBINE DESIGN - PDF
Savio Oliveira Figueiredo, Arielly Assunção Pereira, Erb Ferreira Lins, Marcelo de Oliveira Silva, Jerson Rogério Vaz, UFPA, Brazil
Abstract: Diffusers are widely used in the design of horizontal axis wind turbines, since the influence of the diffuser causes a considerable increase in the efficiency of the wind turbines. This increase is due to the low pressure region that is formed after the passage of flow through the diffuser, which increases the mass flow. At the point of maximum velocity, the rotor can extract more kinetic energy of the flow, increasing its efficiency. The diffuser geometry determines the point of maximum wind velocity, since its aspect ratio changes the shape of the velocity profile. This work presents an experimental and a numerical study of the flow around a conical diffuser, in order to obtain the velocity and pressure profiles along the axis of the diffuser. The computation of the velocity profile internally at the diffuser is done with the finite volume method and this data is compared with experimental data.
Keywords:diffuser; wind turbine; renewable energy.
Presentation Schedule: Wednesday, 10:00-10:20. Session: FMR6-1. Presenter: Arielly Assunção Pereira.
ENCIT2012-065 OPTIMAL DESIGN OF CENTRIFUGAL COMPRESSOR USING TECHNIQUES BASED ON METAMODEL CONSTRUCTION AND COMPUTATIONAL FLUID DYNAMICS (CFD) - PDF
Sandro Kojiro Kurauchi, João Roberto Barbosa, ITA, Brazil
Ramiro Gustavo Ramirez Camacho, Edna Raimunda da Silva, FEI, Brazil
Abstract: This work presents a methodology for performance optimization of Centrifugal Compressor. The channel shape of the meridional plane is parameterized by Bezier curves, to achieve maximum efficiency. As a preliminary test, not including the effects of increased pressure caused by the diffuser. The objective is the maximization of the polytrophic efficiency or total enthalpy starting from a preliminary design. Strategy to find the maximum efficiency is based on the construction of metamodels in conjunction with optimization algorithms. The controlled random search algorithm (CRSA) is then chosen to perform the optimization task. Relatively few design points are exactly evaluated and recorded with their function values in a database for metamodel construction. Radial Basis Functions like multiquadrics are used for this construction (RBF). The optimization methodology based on the construction of metamodels is integrated with CFD techniques, using schemes automatic building of parameterized blade geometries and meshes via "script files" with editing commands written in Tcl/Tk language, which will be interpreted by the commercial software ICEM-CFD, in batch mode. For the numerical calculation of the flow in the centrifugal compressor rotor, the software CFX is used with fluid properties, turbulence model and boundary conditions set through "journal files". This methodology allows making corrections in the initial project of the channel shape meridional plane, without much computational effort.
Keywords:Centrifugal compressor; optimization; CFD techniques; basis radial functions; metamodels.
Presentation Schedule: Thursday, 15:40-16:00. Session: FMR6-2. Presenter: Ramiro G. Ramirez Camacho.
ENCIT2012-311 INDUSTRIAL PROJECT FOR AUTOMATED AERATION OF ORGANIC COMPOST PILES - PDF
Edson Alves Figueira Júnior, Bruno Henrique de Oliveira Mulina, Vinícius Costa Ferreira, UFU, Brazil
Ivana Marcia Oliveira, IFMA, Brazil
Valério Luiz Borges, Solidônio Rodrigues de Carvalho, UFU, Brazil
Abstract: Composting is a safe environmental alternative to reuse and treat organic wastes produced by human-beings. Although decomposition happens naturally, the handling of some factors such as oxygen levels, temperature, moisture content and pH, can improve the process' speed, accelerating microbial activity. Aeration is a crucial practice during the compost process, since it can ensure adequate oxygen supply, control the temperature and reduce the moisture content in the windrows. Therefore, this work aimed to develop an automated aeration process of organic compost piles in order to accelerate and optimize the production of bio fertilizers in a Brazilian industrial plant. Based on previous tests done in the company's standard ventilation, an automated aeration system called SAFA was projected. During system installation the moisture, oxygen levels and temperature were measured to verify the efficiency of the new aeration system. It was verified that SAFA provides a regular oxygenation of the compost piles, thereby reducing the moisture content, increasing the screening rate of the compost and finally reducing the production cycle. Based on these parameters, SAFA is shown as a promising tool for production of organic fertilizers.
Keywords:organic composting; automated system of forced aeration; oxygen content; temperature.
Presentation Schedule: Thursday, 14:40-15:00. Session: FMR6-2. Presenter: Edson A. Figueira Jr..