Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.
ADVANTAGE EXCELLENCE IN ENGINEERING SIMULATION          VOLUME I       ISSUE 3   2007                   HEATING THINGS UP ...
2   ANSYS Advantage • Volume I, Issue 3, 2007   www.ansys.com
EDITORIAL   Where’s the Data?   Companies embracing digital product development must implement   tools for better managing...
CONTENTS          Table of Contents                                                ARTICLES                               ...
CONTENTSDEPARTMENTS 22 PARTNERS      Something in the Mix      Researchers use the Poincaré plane method to obtain quantit...
TURBOMACHINERY       Streamlined       Flutter Analysis       Integrated fluid structure interaction enables high-fidelity...
TURBOMACHINERYFinite element (FE) mesh at the fluid–structure interface   A typical torsional blade mode, where the relati...
TRANSPORTATION/HVACVentilating GiantRailway TunnelsHigh-speed trains in Spaincross more than just the plain.Image courtesy...
TRANSPORTATION/HVAC   Computational fluid dynamics (CFD) contours at three locations within a tunnel show how the longitud...
GLASSGlass-Making Goesfrom Art to ScienceModeling glass furnaces helps improve batchtransition time and reduce product def...
GLASS             Contours of temperature in the combustion space over the melter region of an oil-fired, six-port float g...
THOUGHT LEADERS                                                                                                         Mo...
THOUGHT LEADERS     Simulation also radically lowers the total cost of productdevelopment through less dependency on hardw...
THOUGHT LEADERS                   Thermal analysis shows temperature distribution for a diesel engine piston.been monitore...
ADVANTAGE                                                               s1   It’s Getting Easier to Be Green              ...
ENVIRONMENTAL DESIGNClean Air     Air pollution comes primarily from transportation andpoint-source industrial processes. ...
ENVIRONMENTAL DESIGN: WASTEWATER TREATMENTIn the WorksUsing simulation to model wastewater                                ...
ENVIRONMENTAL DESIGN: WASTEWATER TREATMENTbecome overloaded or underloaded, and, subsequently,                            ...
ENVIRONMENTAL DESIGN: WASTEWATER TREATMENTentrainment. This research found that a longer draft tube                       ...
ENVIRONMENTAL DESIGN: POWER GENERATIONCooling DownPowered-Up Fuel CellsResearchers use probabilistic methods and design op...
ENVIRONMENTAL DESIGN: POWER GENERATION                                                                                    ...
ENVIRONMENTAL DESIGN: POWER GENERATIONMaking Electricitythrough ChemistryAnalysis helps power fuel cell design.By Laura Am...
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
A N S Y S  Advantage  Volumen 1  Issue 3 2007
Upcoming SlideShare
Loading in …5
×

A N S Y S Advantage Volumen 1 Issue 3 2007

5,068 views

Published on

ANSYS Advantage Magazine Volumen 1 Issue 3_2007

  • Be the first to comment

A N S Y S Advantage Volumen 1 Issue 3 2007

  1. 1. ADVANTAGE EXCELLENCE IN ENGINEERING SIMULATION VOLUME I ISSUE 3 2007 HEATING THINGS UP IN THE GLASS INDUSTRY PAGE 8 GREEN POWER RELIABLE WHEELS OLYMPIC PERFORMANCE PAGE s6 PAGE 14 PAGE 20
  2. 2. 2 ANSYS Advantage • Volume I, Issue 3, 2007 www.ansys.com
  3. 3. EDITORIAL Where’s the Data? Companies embracing digital product development must implement tools for better managing simulation information. One unmistakable global trend old data files and analysis models from past simulation is the oncoming wave of digitaliza- projects is difficult and often impossible, even for the tion of the product development people who created them. process. Manufacturers are making Manufacturers are implementing product lifecycle greater use of upfront analysis, management (PLM) solutions in record numbers to deal collaborative tools, digital mock- with issues such as this for engineering data and docu- ups, assembly modeling and ments across the enterprise. According to statistics from complex system simulation. One CIMdata Inc., the PLM market grew 10.4 percent in 2006 to recent study, “The Digital Product reach $20.1 billion; it is forecast to increase at an 8.5 per- Development Benchmark Report” cent compound annual growth rate — exceeding an from the Aberdeen Group, estimated $30 billion by 2011. Handling computer-aided quantifies compelling reasons why design (CAD) files, part lists, technical documents and companies are moving to a paperless process. Specifically, change orders is a lot easier than managing simulation evaluating and refining designs early in development data, however, which is, inherently, a much more demanding enables top companies to eliminate an entire prototype task for PLM because of the huge file sizes and the cycle, in some cases getting products to market a full three complexity of capturing the context of the simulation. months faster and saving up to $1.2 million in development A major step forward in closing this gap is the develop- costs, depending on product complexity. ment of the ANSYS Engineering Knowledge Manager The study also notes major challenges to digital product (EKM) tool. Scheduled for release this year, the Web-based development. Topping the list is accessibility to digital tool will be targeted at managing simulation processes and product information: that is, how the right people can get to data along with capabilities for backup and archival, trace- the right data at the right time. And therein lies a big problem ability, process automation, collaboration, capture of that the engineering simulation community has faced since engineering expertise and intellectual property protection. the early days of the industry: Analysis files — including By managing simulation data and processes within such a models, results data and the processes that go into the framework, companies can more effectively leverage the simulation — are not well managed. More often than not, full power of this critical information and the tremendous keeping track of this information is left to the individual who expertise of the analysts and engineers who created it. ■ generated it, so typically it is buried in obscurity somewhere on a hard drive — or possibly deleted — at the end of a project. Also, this valuable intellectual property may be lost forever when individuals leave the company. Tracking down John Krouse, Editorial Director For ANSYS, Inc. sales information, call 1.866.267.9724, or visit www.ansys.com. To subscribe to ANSYS Advantage, go to www.ansys.com/subscribe. Editorial Director Editors Editorial Advisor About the Cover John Krouse Marty Mundy Kelly Wall Glass has fascinating and unique Fran Hensler properties, and producing it can Production Manager Erik Ferguson Circulation Managers Chris Reeves Chris Hardee Elaine Travers be a complex undertaking. Read Dave Schowalter Sharon Everts about how PFG Building Glass in Art Director Tim Roolf South Africa is changing glass- Susan Wheeler Designers making from an art to a science, Production Assistant Miller Creative Group on page 8. Ad Sales Manager Joan Johnson Beth Bellon Email: ansys-advantage@ansys.com ANSYS Advantage is published for ANSYS, Inc. customers, partners and others interested in the field of design and analysis applications. Neither ANSYS, Inc. nor the editorial director nor Miller Creative Group guarantees or warrants accuracy or completeness of the material contained in this publication.www.ansys.com Workbench, CFX, AUTODYN, FLUENT, DesignModeler, ANSYS Mechanical, DesignSpace, ANSYS Structural, TGrid, GAMBIT Issue 3,and all ANSYS, Inc. ANSYS, ANSYS ANSYS Advantage • Volume I, and any 2007 1 brand, product, service, and feature names, logos and slogans are registered trademarks or trademarks of ANSYS, Inc. or its subsidiaries located in the United States or other countries. ICEM CFD is a trademark licensed by ANSYS, Inc. All other brand, product, service and feature names or trademarks are the property of their respective owners. 1 ANSYS Advantage • Volume I, Issue 3, 2007 www.ansys.com © 2007 ANSYS, Inc. All rights reserved.
  4. 4. CONTENTS Table of Contents ARTICLES 4 TURBOMACHINERY Streamlined Flutter Analysis Integrated fluid structure interaction enables high-fidelity turbomachinery blade flutter analysis. 6 TRANSPORTATION/HVAC Ventilating Giant Railway Tunnels 4 High-speed trains in Spain cross more than just the plain. 8 GLASS Glass-Making Goes from Art to Science Modeling glass furnaces helps improve batch transition time and reduce product defects. 10 THOUGHT LEADERS Getting It Right the First Time In a corporate-wide initiative, Cummins Inc. refines designs early with Analysis Led Design to shorten development time, reduce costs 6 and improve product performance. 13 BIOMEDICAL Special Delivery Researchers use simulation and medical imaging to explore new options for managing pain. 14 TRANSPORTATION More Certainty by Using Uncertainties 14 Engineers apply probabilistic methods to historically deterministic problems. 16 GOVERNMENT AND DEFENSE Out of Harm’s Way Engineers used simulation to design an innovative military gun turret. 18 MARINE Designing Out the Weakest Link Engineering simulation validates the design of a mooring system component, a critical wheel/chain assembly that holds ships in place during oil and gas 16 operations in the North Sea. 20 SPORTS Going for the Gold Simulation helps design low-drag canoes for Olympic-medal performance. 202 ANSYS Advantage • Volume I, Issue 3, 2007 www.ansys.com
  5. 5. CONTENTSDEPARTMENTS 22 PARTNERS Something in the Mix Researchers use the Poincaré plane method to obtain quantitative time scale information from CFD simulations. 24 Cluster Computing with Windows CCS New clustering technology from Microsoft speeds up engineering simulation. 24 26 TIPS & TRICKS Component Mode Synthesis in ANSYS Workbench Simulation CMS superelements provide flexibility of simulation models while reducing the number of degrees of freedom for highly efficient solutions. 28 ANALYSIS TOOLS Accelerating to Convergence ANSYS VT Accelerator technology can help solve nonlinear transient and static analyses faster. 26 30 Seeing is Believing Developments in version 11.0 software from ANSYS allow inclusion of solid parts during pre- and post-processing, making for more intuitive problem setup and results visualization. 32 Predicting Liquid Atomization Simulation can be used to produce sprays with desired characteristics using the FLUENT VOF model. 32Spotlight on Engineering Simulation forEnvironmental Design s1 It’s Getting Easier to Be Green From air to water to power, industries are using engineering simulation to uncover new ways to be environmentally responsible. s3 In the Works Using simulation to model wastewater treatment plants effectively. s6 Cooling Down Powered-Up Fuel Cells s1 Researchers use probabilistic methods and design optimization to improve heat-transfer characteristics of fuel cell stacks. s8 Making Electricity through Chemistry Analysis helps power fuel cell design.s10 The Future of Fuel A European research project is developing internal combustion engines powered by hydrogen. s10www.ansys.com ANSYS Advantage • Volume I, Issue 3, 2007 3
  6. 6. TURBOMACHINERY Streamlined Flutter Analysis Integrated fluid structure interaction enables high-fidelity turbomachinery blade flutter analysis. By Robin Elder and Ian Woods, PCA Engineers Limited, Lincoln, U.K. The “flutter” of blades within compressors and turbines Simon Mathias, ANSYS, Inc. is a serious cause of machine failure that is difficult to predict and expensive to correct. This aeromechanical phe- nomenon usually occurs at a blade natural frequency and involves sustained blade vibration resulting from the changing pressure field around the blade as it oscillates. For the process to occur, it is necessary that, over one cycle, there is an input of energy from the gas stream to the blade of a sufficient magnitude to overcome the mechanical damping. Clearly, flutter is dependent on both the aerodynamic and structural characteristics of the blade, and, until recently, it has been beyond the design capability to satisfactorily investigate and avoid this phenomenon. Historically, empirical design criteria have been used based on parameters involving blade natural frequencies and flow transit times, but these methods fail to take into account generally found vibrational modes or the influence of adjacent blades. Improvements in unsteady computational fluid dynamics (CFD) capability combined with the ability to easily and accurately transfer information between CFD and finite element analysis (FEA) has enabled the development of an advanced yet efficient and cost-effective methodology for analyzing forced vibration processes. A key enabling development now provided by ANSYS, Inc. is the ability to deform the CFD computational grid in response to deformations at the fluid structure interface and integrate this with unsteady flow computations. The process is straightforward to set up and is facilitated by theANSYS Mechanical analysis tools can predict vibration modes that occur over an entire intuitive and intrinsic functionality of the user interface andwheel from a single blade component model. Shown here are exaggerated deformations layout in the ANSYS Workbench platform. PCA Engineersfor a four-nodal diameter mode shape, meaning that the mode repeats itself four timesover the entire wheel circumference. Engineers are interested in determining whether Limited, based in the U.K., has utilized this capability byvibration modes such as these will be amplified by interaction with the fluid or safely mapping time-dependent deformations computed from adamped out. finite element analysis to the CFD computational grid. As a rule, blade flutter occurs at a blade natural frequency that is determined together with its corresponding mode of vibration using traditional finite element techniques. A bladed disc assembly can be classified as a rotation- ally periodic structure, and, therefore, the mode shape of adjacent blades within a row are fully defined by a phase 4 ANSYS Advantage • Volume I, Issue 3, 2007 www.ansys.com
  7. 7. TURBOMACHINERYFinite element (FE) mesh at the fluid–structure interface A typical torsional blade mode, where the relative Equivalent stresses amplitude of each node point on the gas swept surface of the blade is known as a function of timedifference. This phase difference (the inter-blade phaseangle or IBPA) depends on the number of blades in the rowand the number of patterns repeating around the annulus.This latter parameter is often called the nodal diameter (ND)and can move either in the direction of rotation or againstthe direction of rotation. The significant development is that this modal displace-ment information now can be applied to the computationalgrid and the resulting time varying flow through a blade rowas well as the dynamic pressure field over each definedblade calculated using ANSYS CFX software. The computeddynamic pressure distribution and the corresponding modaldisplacements then are used to compute the work done onthe blade over one complete cycle. If the net work done onthe blade is positive, then work is being imparted to theblade, creating negative damping, a potentially unstablesituation leading to a self-sustained vibration (flutter) likely tocause a material fatigue failure. On the other hand, if theaerodynamic work done on the blade is negative, the blade Deformations of a four-nodal diameter which repeat once over each quarter of the wheel, were exported from the modal analysis vibration mode to ANSYS CFXmotion is doing work on the fluid and leads to a stable or software as a boundary profile. The mode shape is used to create a periodicdamped vibration. boundary motion in the CFD software and to evaluate the net work input due to In the aerodynamic damping case illustrated, the blade the blade motion.is stable (no flutter) because the damping is always positive.This information is critical to the designer as blades are 0.2relatively easy to modify before manufacture but extremelycostly to rectify in an operational plant. By utilizing blade 0.16flutter prediction early in the design cycle, costly damageand repairs can be avoided. This integrated design and 0.12analysis approach in multiphysics technology from ANSYS Dampingcan lead to improved quality and dependability of the Coef 0.08 (log)design process, realizing further cost benefits to clients. ANSYS, Inc. and PCA Engineers now are applying such 0.04technology to a wide range of applications extending fromlarge steam turbines to small turbochargers. These tech- 0niques are assisting engineers to design compressor and -40 -30 -20 -10 0 10 20 30 40 50 60 70 80turbine blading in which both aerodynamic efficiency and Inter-Blade Phase Angle (deg)structural integrity are paramount over the operational rangeof the machine. ■ Damping coefficients can be calculated from the CFD results. Negative net work input due to blade motion results in a positive damping coefficient. Negative www.pcaeng.co.uk damping coefficients induce sustained blade vibration, or flutter, which could lead to blade failure. These results show positive damping for all inter-blade phase angles.www.ansys.com ANSYS Advantage • Volume I, Issue 3, 2007 5
  8. 8. TRANSPORTATION/HVACVentilating GiantRailway TunnelsHigh-speed trains in Spaincross more than just the plain.Image courtesy Eurorail Group.By José Carlos Arroyo and Pedro Luis Ruiz, INECO-TIFSA, Madrid, SpainYannick Ducret and Roberto Garcia, ANSYS, Inc. Sunny beaches filled with sunbathers may be the first thing that comes to mind when imagining Spain. However, the reality of its geography is a lot more variable. In fact, the Iberian Peninsula sports many mountain ranges that largely hinder the development of complicated infrastructure, such as the high-speed rail network that is planned to connect Spanish urban areas. This project has led the Spanish railway industry to bore some of the world’s longest high-speed transit railway tunnels, such as the 28-km Guadarrama tunnel and the 24.5-km Pajares tunnel. INECO-TIFSA, a transport and telecommunication company located in Madrid, Spain, has contributed to the ongoing expansion of high-speed railways throughout the country by participating in the design of superstructures, such as these giant tunnels. When designing a railroad tunnel, the ventilation system is a critical component. The ventilation units themselves consist of longitudinal jet fans that are placed at several positions along the tunnel. Their performance is affected severely by air disturbances that result from the motion of a train traveling in the tunnel at speeds of up to 350 km/h (218 mph). Not only does the train movement quickly force the air toward both tunnel exits, it also creates a complex system of pressure waves that propagate throughout the space. A positive-amplitude pressure wave is created when the train enters the tunnel. When the train’s rear end passes into the tunnel, another wave, of negative amplitude, originates at the tunnel entrance. Both waves propagate toward the tunnel exit where they are primarily reflected. Traditionally, 1-D or 2-D simulations have been satisfac-Pressure contours on a train with vortices shown by streamlines in a tunnel tory to predict the average pressure correctly inside the6 ANSYS Advantage • Volume I, Issue 3, 2007 www.ansys.com
  9. 9. TRANSPORTATION/HVAC Computational fluid dynamics (CFD) contours at three locations within a tunnel show how the longitudinal velocity changes in the tunnel as a train passes through it. The plane cuts represent the position of jet fans where fluctuating velocities have been monitored.tunnel. Only by means of a complete 3-D simulation, a train enters a tunnel, air first escapes at the tunnelthough, is it possible to obtain an accurate estimate of the entrance at the side of the train, both because it is thevelocity components, magnitude and their distribution in the closest exit and because the mass of air between the fronttunnel sections in order to allow for accurate fan sizing. of the train and the tunnel exit has yet to be put in motion. To design the ventilation system for a long (>5 km) When the train has passed, the flow then changes direction.tunnel, INECO-TIFSA chose FLUENT software to perform a At that moment the air is pushed by the train and travelsfull 3-D unsteady simulation of a train passing through such backward in the narrow gap between the train and thea tunnel. The movement of the train was simulated using the tunnel. Speeds of up to 35 m/s were observed at the fanFLUENT sliding mesh capability, in which the train and the positions. Furthermore, some sudden changes of slightlydomain that it encompasses slide along a non-conformal higher amplitude could be seen when the front of the traininterface. The interface was placed at the tunnel wall, and reached the jet fans, showing how carefully this equipmentthe mesh was extruded accordingly. Due to the speed of needs to be selected.the train, the ideal gas model was used to account for As expected, the pressure waves created by the train’sthe effects of compressibility. The computations were motion do have a discernible effect on flow patterns withinperformed using the pressure-based solver, which was the tunnel. Seconds after the train has passed the jet fans atchosen because the flow is only slightly compressible — the entrance of the tunnel, the wave patterns form such thatthat is, there is only a weak coupling between density and they accelerate the air flow by up to 25 m/s. When the air isvelocity, and, thus, the computation does not require the compressed by a positive-amplitude wave, the air velocitydensity-based solver. This unsteady simulation was diminishes according to conservation of mass, while theperformed using non-iterative time-advancement (NITA) inverse (acceleration) occurs if the wave is of negativein order to reduce the computational time required. This amplitude. The train creates both of these types of waves asapproach was validated by a series of 2-D computations. it passes through the tunnel, thus inducing both accelera-Special consideration was given to the determination of the tions and decelerations in the surrounding tunnel airflow.appropriate time step, since it needed to be small enough to This complex and decaying phenomenon then continuespredict the wave’s propagation correctly. long after the train has exited the tunnel. Even though the The velocity components and the static pressure were highest velocities observed are longitudinally oriented, themonitored in seven different locations along the tunnel transversal velocity profiles revealed the benefits of a 3-Dlength corresponding to the ventilators’ positions. The flow study, since velocities of the same order of magnitude werepatterns also were analyzed using velocity contours in observed. Overall, this modeling approach has shownvarious sections of the tunnel. The results showed the interesting results and proven beneficial for INECO-TIFSAamplitude of the flow created by the train’s passage. When by the level of detail achieved. ■www.ansys.com ANSYS Advantage • Volume I, Issue 3, 2007 7
  10. 10. GLASSGlass-Making Goesfrom Art to ScienceModeling glass furnaces helps improve batchtransition time and reduce product defects.By Eddie W. Ferreira, PFG Building Glass, Springs, South Africa To create glass from its raw in which the glass is cooled to a suitablematerials is to invest in both the art and working temperature. There are variousthe science of the process. Glass is a methods of accomplishing each stepfascinating engineering material with that affect the process differently. Differ-unique properties; however, producing ent glass compositions require differentit can be a complex undertaking and is operating envelopes, due to the changeoften thought of as an art. As a result, in physical and chemical properties.commercial glassmakers strive contin- Because glass-making requires Contours of batch species fraction in the glass domainually to understand the science of its furnace temperatures of 1500 degrees C of a container furnace. The red area represents themanufacture in order to optimize and (about 2700 degrees F), heat transfer and introduction of a new species into the glass flow.improve the process. As one such chemical diffusion dominate the processmanufacturer, PFG Building Glass in kinetics, and the reaction tank itself is Once these simulation results wereSouth Africa is using FLUENT compu- slowly dissolved by the molten glass. acquired, time-dependent events, suchtational fluid dynamics (CFD) software These factors make experimental studies as color transitions, were incorporatedto model the flow inside its glass difficult. As an alternative, simulation into the simulation and accounted for byfurnaces, track processing defects and arises as a good way to understand switching to the transient solver in theimprove overall production systems. how furnaces behave and how process FLUENT product. To simulate this more At the basic level, glass-making improvements can be made. complicated type of process, PFGconsists of three steps. The first is Using the 3-D version of FLUENT enabled the species transport model inmelting a blend of raw materials, which software and the pressure-based solver, FLUENT software and incorporated itscan include sand, limestone, soda ash, PFG Building Glass developed a CFD own batch models via user-definedfeldspar and saltcake. The next is solution for steady-state glass process- functions (UDFs) for the species proper-refining, in which bubbles contained ing conditions. The company created a ties, boundary conditions and sources.within the molten raw materials are simplified initial simulation, one that did These additions allowed the team toremoved. Finally, there is conditioning, not include any time-dependent events. observe factors such as mixing. Apart from the glass flow itself, what Melter happens in the combustion space above the processing glass is very important. Combustion that occurs in this region of the furnace is a heat Waist source for melting and heating the glass mixture. In order to include this region in the analysis, PFG incorporated Refiner combustion, radiation and turbulence modeling into the simulation. By includ- ing these factors, the model complexity Conditioner was greatly increased.Model of a float glass furnace. The most common method for glass production is floating molten glass on top of The combustion space modelmolten tin, thus giving it the name “float glass.” This process results in the formation of plates or ribbons of glass. and the glass flow model then were 8 ANSYS Advantage • Volume I, Issue 3, 2007 www.ansys.com
  11. 11. GLASS Contours of temperature in the combustion space over the melter region of an oil-fired, six-port float glass furnace. Red areas identify regions of higher temperature.combined into a coupled simulation, factors driven by this transition time, while also maintaining long furnace life,making use of the FLUENT non- glass that does not fall within approved all without a hit-and-miss approach.premixed combustion model, discrete specifications is produced with an Product quality has improved as aordinates (DO) radiation model and associated loss of revenue. Any reduc- result of defect tracking, and lossesrealizable k-ε turbulence model. tion in transition time is, therefore, of have been reduced as the process hasFurther UDFs were used to define the great value. PFG has been able to become more of a science thanmaterial properties and source terms. partially model this transition process an art. This experience and theFor boundary conditions, it was impor- using FLUENT software, leading to models drawn up allowed PFG to sim-tant to maintain the glass zone as a modifications in operating procedures. ulate planned expansions before theylaminar zone and the combustion zone The use of CFD modeling has led were installed and, thereby, eliminateas a reaction zone. to a better understanding of glass problem areas before installation. ■ The quality of the final glass flows and combustion conditionsproduct is influenced by the presence inside glass furnaces. This has allowed The authors would like to acknowledge Peet Drotskie and Corne Kritzinger from PFG, whoof small bubbles, which manufacturers PFG Building Glass to achieve its laid the groundwork for these modeling efforts,try to remove from the batch during a objective of producing high-quality as well as Danie de Kock and his support teamrefining phase because bubbles can glass at the lowest possible price, at Qfinsoft for their invaluable input.lead to discrete faults in the finalproduct. There are numerous sourcesthat can lead to an unacceptable rise inthe number of faults. Using simulationfor defect tracking has helped PFG topinpoint the areas that are most proba-bly the origin for the faults. PFGaccomplished this with the reverseparticle tracking capability in theFLUENT product. By defining trackinglocations throughout the glass fluiddomain and using the FLUENT dis-crete phase model (DPM), PFG wasable to examine a particular particle’sflow path history and determine statis-tically probable fault positions in thefinal glass ribbon. One other complication of a batchprocess is the transition from onebatch to another, which involvesmoving the complete furnace glassvolume. Usually the transition process Contours of velocity magnitude through the center of a float furnace. The simulation includes both the combustiontakes a number of days. As a result of space above the glass melt and the melted glass itself.www.ansys.com ANSYS Advantage • Volume I, Issue 3, 2007 9
  12. 12. THOUGHT LEADERS Modal analysis identified deformation of the crankshaft.Getting It Rightthe First TimeIn a corporate-wide initiative, Cummins Inc. refines designsearly with Analysis Led Design to shorten development time,reduce costs and improve product performance.By Bob Tickel, Cummins Inc., Indiana, U.S.A. In developing complex mechanical products such as diesel engines, going through multiple build-and-test hard- ware prototype cycles to verify performance, stress and fatigue life is tremendously expensive and time-consuming. This issue can be addressed by evaluating and refining designs with analysis tools up front in development, so fewer test cycles will be needed later in development. Five years ago, such a Simulation Driven ProductBob Tickel Development approach was started at Cummins Inc., aDirector of Structural corporation of complementary business units that design,and Dynamic Analysis manufacture, distribute and service engines and relatedtechnologies, including fuel systems, controls, air handling, filtration, emissionsolutions and electrical power generation systems. Applications include trucks,construction and mining equipment, agricultural machinery, electrical generators,fire trucks, recreational vehicles, buses, cars, SUVs and pickup trucks. TheCummins Analysis Led Design (ALD) strategy is a corporate-wide initiative tochange the prevalent test-first culture; it has had a major impact at the company,with significant benefits that include shorter development time, lower costs andimproved products. ALD can shorten product development time by getting designs right the firsttime. Many Cummins-designed parts have extensive lead times because tooling The Cummins QSK78 engine delivers more power thanneeds to be created. Beyond this, traditional hardware testing can take weeks or any other engine for gigantic haulers in the miningeven months to validate a design. Leveraging analysis early in the process can industry. The 18-cylinder, 12-ton super-engine is rated at 3,500 horsepower and stands almost eight feet high.eliminate tooling changes and repetition of lengthy endurance testing, thus Cummins also provides engines for agricultural andproviding significant reductions in overall development time. industrial equipment and heavy-duty pickup trucks.10 ANSYS Advantage • Volume I, Issue 3, 2007 www.ansys.com
  13. 13. THOUGHT LEADERS Simulation also radically lowers the total cost of productdevelopment through less dependency on hardware testsand a reduced number of long-hour tests, which sometimescan last for days. At Cummins, some of this traditionalendurance testing can cost in the range of $50k to $100kper test, so eliminating even a single cycle can result in sig-nificant savings. The intention is not to eliminate all testingbut, rather, to use targeted component and assembly-leveltesting first to validate analysis models and then to validatethe overall design with only a few long-hour tests of theentire engine. Savings also are achieved by eliminatingredesigns, in which costs are lowered by reducingresources required to manage the design process (engi-neering, drafting, clerical time, etc.) as well as reducing This customized Kenworth tanker truck has a Cummins 565-horsepower engine.retooling costs. While shortening development time and lowering costsare important aspects of ALD, it can be argued that the validations. Now when a new heavy-duty engine design ismost significant benefit of the approach is the ability to being developed, a series of repetitions are done throughcreate improved products by considering a broad range of simulation until the entire block meets the design limits. Thisdesign alternatives. Simulation allows engineers to readily requires the time of one analyst for about a month of work,perform what-if studies and large-scale design of experi- or approximately $7k. Once the hardware is procured, rigments in order to understand more fully the design space testing is completed on the initial pass — a first for this typeand trade-offs involved. Otherwise, once the first set of of design. The result is that a minimum $30k of enginehardware is created, the design space narrows and designs testing is eliminated. Also, redesigns are eliminated that,are much harder to modify. most likely, would have occurred over many more weeks or Various measures have been used within Cummins to months and at an additional cost of $100k ($72k of righelp determine the effectiveness of ALD. In looking at test and $30k of engine testing), which does not include thetime and cost in one example, validation testing for a significant additional expense of prototype hardware.cylinder block traditionally required $72k of rig testing and There are several reasons why ALD has been successful$30k to $80k for engine testing for a single block design. at Cummins: It is a top-down initiative that was driven byEach repetition costs the same amount: in the range of upper management, appropriate resources were allocated,$100k to $150k. Testing usually took about one month, and an infrastructure was established to support the initiative.once hardware was available. Lead time for the tooling and From the beginning of the program, top managementpart procurement took about 12 weeks. has been a strong proponent of ALD. Cummins’ chief Through the ALD initiative, engine testing has been technical officer coined the acronym ALD, and he hasremoved as a requirement for some cylinder block continued to push the initiative. The progress of ALD hasIn the development of Cummins diesel engines, engineers use the ANSYS Mechanical software to determine (left to right) cylinder block deformation and stresses, cylinder headassembly stresses and temperature distribution in the cylinder head and valves.www.ansys.com ANSYS Advantage • Volume I, Issue 3, 2007 11
  14. 14. THOUGHT LEADERS Thermal analysis shows temperature distribution for a diesel engine piston.been monitored continually and reported in quarterly and Six Sigma tools. ESW defines the work, tools and limitsmessages by Tim Solos, Cummins CEO. At the executive required to release a part for production. This became alevels, there has never been a question about whether to natural focus for ALD as Cummins examined where testingreduce testing and increase analysis but rather how to best was being reduced and where analysis was beingaccomplish this objective with limited resources. increased. Six Sigma has been an invaluable support for Along with driving ALD, Cummins management ALD in validating new tools and methods to ensure thatprovided resources to do more analysis. Shortly after the analysis can be used to replace testing. So, ALD is theALD initiative was started, a technical center was set up initiative, ESW is the process to ensure that all necessary(Cummins Research and Technology, or CRT, in India). This work is completed and Six Sigma is the set of tools used toanalysis center focuses solely on design, computational determine that the appropriate work is included.fluid dynamics (CFD) and structural analysis in supporting In performing the underlying work for ALD, theall Cummins business units. Structural and Dynamic Analysis group within the Cummins Infrastructure to support ALD at Cummins has taken Corporate Research and Technology organization istwo forms: Engineering Standard Work (ESW) processes responsible primarily for developing tools and methods as well as conducting analyses to ensure that structural components meet both reliability and durability require- ments. The group partners with key software vendors in efforts to develop improved simulation tools, and one of the primary relationships is with ANSYS, Inc. In fact, the relationship has been the benchmark set for subsequent partnerships. Technology from ANSYS has become the primary finite element tool within all Cummins business units for conducting static structural, thermal, transient thermal, modal, harmonic and other analyses. This partnership with ANSYS has resulted in joint development of advanced features in continuing to meet analysis needs at Cummins. Any culture shift is difficult, requiring vision, leadership, planning and tangible benefits. The ALD initiative, in particular, has driven considerable change and has proven to be of tremendous value at Cummins. While significant progress has been made, there is room for expansion, and Cummins will continue to evaluate new and improvedCoarse mesh of detailed geometry for an inline six-cylinder head created using the technologies, processes and strategies in using simulation toANSYS Workbench platform further strengthen its position in the diesel engine industry. ■12 ANSYS Advantage • Volume I, Issue 3, 2007 www.ansys.com
  15. 15. ADVANTAGE s1 It’s Getting Easier to Be Green s3 In the Works s6 Cooling Down Powered-Up Fuel Cells s8 Making Electricity through Chemistry s10 The Future of FuelImage © iStockphoto/Elena ElisseevaIt’s Getting Easier to Be GreenFrom air to water to power, industries are using engineering simulationto uncover new ways to be environmentally responsible.By Dave Schowalter, ANSYS, Inc. The term “green engineering” has become ubiquitous that show how they are developing green technologies.in recent years, with references even on the covers of trade Of particular note are General Electric’s ecomagination™,journals and magazines. The U.S. Environmental Protection the BP™ campaign Beyond Petroleum and ChevronAgency defines green engineering as “the design, commer- Corporation’s willyoujoinus.com advertising promotion.cialization and use of processes and products that are One thing is clear: Major companies believe there isfeasible and economical while reducing the generation of money to be made in developing environmentally friendlypollution at the source and minimizing the risk to human technology, which should encourage even the mosthealth and the environment.” So while green engineering contrarian environmentalist.encompasses environmental engineering, it also can refer In building a better world, global companies areto any engineering field in which environmental and human learning that the right engineering simulation can improvehealth impacts are minimized. Increasingly, the term has efficiency in the design of real-world systems. Simulationbecome associated with sustainable development, in capabilities from ANSYS, Inc. are particularly visible in thewhich processes and products can continue to be produced areas of pollution control, architecture, energy and sustain-indefinitely with a minimum of resource depletion or able technology. This spotlight on the environmentalenvironmental degradation. industry provides details about how hard-working users of Along with increased awareness of environmental engineering solutions from ANSYS are improving theimpact, well-known corporations have launched campaigns environment. Perhaps readers will find themselves inspired.www.ansys.com ANSYS Advantage • Volume I, Issue 3, 2007 s1
  16. 16. ENVIRONMENTAL DESIGNClean Air Air pollution comes primarily from transportation andpoint-source industrial processes. In the transportationarena, there is particular emphasis on particulates andnitrous oxides (NOx), with increasing efforts to reduce car-bon dioxide emissions through efficiency improvements.Reducing any type of pollution can involve heavy simulationusage for flow, chemistry, heat transfer and thermal stressminimization. Particle tracks in a wet SO2 scrubber in which simulation was used Industrial sources are concerned with particulates, NOx, to optimize pollutant capture efficiency. Image courtesy URS Corporation.and carbon dioxide, as well as sulfur oxides (SOx) andmercury. The low pollutant levels achieved today throughoptimized furnace combustion and optimized flow distribu- Green Buildingtion in downstream pollutant capture systems would not be Green building refers to designing commercial and res-possible without virtual prototyping through computational idential buildings that minimize non-renewable energyfluid dynamics (CFD). Additionally, minimization of material usage; use materials whose production has a minimalusage requires an understanding of thermal stress loads environmental impact; and use heating, ventilation and airthrough structural analysis. conditioning methods that maximize air quality. Safely minimizing material usage and maximizing passive ventila-Clean Water tion through natural circulation makes this an active and Engineers are using fluid flow modeling — including growing area for simulation.solutions from ANSYS — to optimize both municipal andcommercial purification processes, such as tank mixing, Renewable Energyultraviolet disinfection, chlorination and ozone contactors. Of all renewable energy technologies, wind power hasModeling also comes into play in wastewater treatment, taken the most advantage of simulation capabilities.which involves similar processes, in addition to phase Today’s large wind turbines require advanced materials,separation. increased efficiency, reduced weight while avoiding fluid Protection of fish is another aspect of clean water, and structure interaction, and the ability to withstand seismicsimulation has been used to design oxygenation systems vibrations. Because the power that can be extracted scalesand retrofits in hydropower dams, that are aimed at increas- as the cube of the wind velocity, placement decisions caning downstream oxygen levels. Modeling of water intake have a major impact on the profitability of a project. Otherstructures at industrial plants also is contributing to reduc- renewable energy technologies that take advantage oftion of ecosystem impact. products from ANSYS include tidal power systems, solar Run-off and drift from commercial and residential power installations, and biomass power and energy.pesticide treatments can affect water as well as air; simula-tion is used to optimize chemical dosing, and to model and Sustainable Technologyunderstand dispersion. Drastic reductions in energy usage and pollution produc- tion are possible with new technologies such as fuel cells, advanced nuclear power plants (including nuclear fusion research), advanced coal power (including gasification) and hybrid automobiles. For these technologies, simulation is in on the ground floor of development, playing an especially active role in next-generation products. In order to support the ever increasing rate of technology development that is required for global environmental sus- tainability, computer aided engineering tools themselves must be scalable and sustainable, which is why ANSYS gives the highest priority to developing multidisciplinary, multiphysics tools all within a single accessible environment, deployable on the desktops of engineers in the small venture start-up as well as on the large parallel servers in engineering departments of major multinational corporations. ■ ReferencesFinite element analysis was used in the design of a solar car, which hadsevere weight limitations. Image shows the stress analysis on A-Arm clevis [1] U.S. Environmental Protection Agency,for the car’s suspension. Image courtesy University of Toronto Blue Sky Solar Racing. http://www.epa.gov/oppt/greenengineering, 2006.s2 ANSYS Advantage • Volume I, Issue 3, 2007 www.ansys.com
  17. 17. ENVIRONMENTAL DESIGN: WASTEWATER TREATMENTIn the WorksUsing simulation to model wastewater By David J. Burt MMI Engineeringtreatment plants effectively. Bristol, U.K. In response to various European environmental legisla- some process knowledge. This article illustrates a few of thetive drivers — which include urban wastewater treatment, processes and explains how they are best addressed withfresh-water quality standards for protection of fish and ANSYS CFX software and multiphase modeling techniques.water framework directives — U.K. water companies have The basic sequence of operations at a wastewaterembarked on a new asset management plan. Part of this treatment site with an ASP plant includes the followingplan requires the treatment of significantly greater amounts stages:of wastewater, either by building new treatment plants or ■ Inlet works with de-gritting and flow balancingby increasing flows through existing plants or works. At the ■ Primary settlementsame time, many sites face additional tighter constraints for ■ Activated sludge treatment in aeration laneseffluent discharge. The majority of wastewater is treated in ■ Secondary settlementmodern, large-capacity activated sludge process (ASP) ■ Tertiary treatmentplants. Water companies have been making increased useof analytical process modeling tools, such as computational Inlet Worksfluid dynamics (CFD), to find capital cost savings, achieve In most U.K. works, the wastewater enters from anperformance improvements and improve energy savings for upstream combined sewer system. This wastewater is athese plants. mixture of rain water and sewage loaded with solid particles A modern wastewater ASP includes several operational of irregular size, shape and density. A large inlet worksstages that may be modeled with CFD. However, using CFD removes gross solids and delivers equal flows and loads toto investigate these unit operations successfully requires the multiple lanes of an ASP; otherwise, the lanes may Chemical Addition Primary Aeration Secondary Tertiary Inlet Works Settlement Lanes Settlement Settlement Discharge Air Sludge Digestion Dewatering Sludge Treatment Land applicationwww.ansys.com ANSYS Advantage • Volume I, Issue 3, 2007 s3
  18. 18. ENVIRONMENTAL DESIGN: WASTEWATER TREATMENTbecome overloaded or underloaded, and, subsequently, of the wet solids density. The total solids concentration thusthey will not work as well. CFD modeling of the inlet works is determined from the sum of the size groups progressingcan be used to determine the equality (or inequality) of the through the tank. This multiple drift flux modeling techniqueflow distribution among the lanes, as well as the trajectory has been used to determine the optimum number ofand final resting place of solids that move independently of primary tanks and their required side wall depth for newthe bulk fluid. For example, a discrete particle tracking build sites in the U.K., thus minimizing the land use require-model may be used to determine the solids retention ment and reducing overall civil engineering costs.efficiency of grit traps and balancing tanks, whereas acontinuum multiphase model may better show how solids Activated Sludge Treatment in Aeration Lanesmove independently of the water down the different lanes of After primary separation, the wastewater stream passesa distribution chamber. into a series of aeration lanes in which bio-chemical reac- tions occur that convert the solid particulate waste intoPrimary Settlement activated sludge. The sludge then can agglomerate (or After removal of the larger solids in the inlet works, the flocculate) into large clusters of particles that can be morewastewater passes into a primary separation zone. The pri- readily separated by sedimentation. The bio-chemicalmary tanks are often circular with a central influent, or riser reaction rates depend on the levels of dissolved oxygenpipe, at the center of the tank. Separation of solids occurs present within the wastewater. These levels can be modeledby settlement. The ability to retain solids depends on the with multiphase CFD. A surface aerator, which draws liquidbalance between the radial up-flow velocity in the tank and and solids from the lower region of the tank up through athe solids’ settling velocity. In order to model settlement in a draft tube and then sprays them back across the surface ofprimary tank with CFD, a multiple drift flux model is used in the tank, influences the solids distributions within the tankwhich the influent solids particle size distribution is defined and also introduces oxygen into the aeration lane. A studyas a series of size groups (mass fractions). Each size group that varied the length of a draft tube diffuser was performedhas a drift settling velocity pre-calculated from knowledge to investigate how the geometry affected the sludge bed The interstage chamber was modeled with ANSYS CFX software. Streams A primary settling tank was modeled with multiple drift fluxes. This from an inlet culvert demonstrate the typical flow patterns at the inlet plot shows the stratified distribution of solids through a typical 30-m distribution chamber. The streamlines are colored by time, with blue diameter tank. representing the initial time at 10 seconds. The inlet works for a large ASP illustrates the typical scale. Storm settling tank influents4 ANSYS Advantage • Volume I, Issue 3, 2007 www.ansys.com
  19. 19. ENVIRONMENTAL DESIGN: WASTEWATER TREATMENTentrainment. This research found that a longer draft tube arrangements that increase throughput and maintain theshould be used with the surface aerator under investigation. effluent solids at more than 40 sites.This change was shown to maximize the aeration and This article illustrates four examples of applying CFD tomixing capacity. wastewater systems. Many other unit operations may be examined with similar models to those described here. TheSecondary Settlement extension of aeration lane modeling to include microbial After traveling through the aeration lane, the wastewater population balances and bio-kinetic reactions (the ASM1undergoes secondary treatment in a clarifier. The activated model) currently is being investigated at MMI Engineering. ■sludge settles out and the effluent passes over a v-notchedside weir. The secondary clarifier may be modeled with an For further guidance on using CFD for wastewater modeling, consult the Aqua Enviro training course “Introduction to CFD Modeling for Water andextended drift flux model incorporating both sludge Wastewater Treatment Plants” at www.aqua-enviro.net/calendar.asp.settlement and rheology models defined as functions of localconcentration. The results of simulation provide both thegradient of solids within the tank ranging from less than References5mg/l in the surface water to greater than 20,000 mg/l in the [1] Burt, D.; Ganeshalingam, J., “Design and Optimisation of Finalcompressive zone near the bottom of the tank and a measure Clarifier Performance with CFD Modelling,” CIWEM/Aqua Enviro joint conference, Design and Operation of Activated Sludge Plants,of the likely effluent solids concentration (solids going over April 19, 2005.an exit weir, typically in the range of 10 to 30 mg/l). This [2] Robinson C.; Wilson R.; and Hinsley S., “Calculating Primary Settlingmethod has been used extensively to prove clarifier Tank Performance with Computational Fluid Dynamics,” 4th Annualperformance — as compared with idealized mass flux CIWEM Conference, Newcastle, U.K., September 12–14, 2006.theory — and to optimize the position of retrofit baffles toallow a higher flow throughput for the same effluent solidsconcentration on existing units. MMI Engineering has usedthese techniques to design optimum clarifier influent Deflection ring Stilling well McKinney baffle Inlet pipe CFD was used to determine the influence of the draft tube depth on sludge These simulation results depict solids concentration for a radial bed entrainment for the surface aerator in the bio-reactor modeled here. cross section of a wastewater clarifier. Red indicates areas of Iso-surfaces of solids concentration are shown using blue at 3,000 mg/l higher concentration. and yellow at 20,000 mg/l. Streamlines identify flow patterns that pass up through the draft tube and are projected out, by way of the aerator, across the tank surface. The surface aerator of this bio-reactor is used to resuspend the solids bed Activated sludge is settled out in this clarifier. Flow enters the tank from from within an aeration lane and to entrain air into the reactor. the top and flows radially outward.www.ansys.com ANSYS Advantage • Volume I, Issue 3, 2007 s5
  20. 20. ENVIRONMENTAL DESIGN: POWER GENERATIONCooling DownPowered-Up Fuel CellsResearchers use probabilistic methods and design optimizationto improve heat-transfer characteristics of fuel cell stacks.By Andreas Vlahinos, Advanced Engineering Solutions, Colorado, U.S.A. With pure water as the only byproduct, fuel cells are one of the most environmentally safe alternatives for providing power for vehicles and stationary applications: Stacks of the devices generate electricity directly from hydrogen and oxygen. One major concern in designing fuel cell stacks is dissipating heat created during the electrochemical conver- sion process. Thermal hot spots within the fuel cell stack may degrade performance, induce thermomechanical stresses and shorten the useful life expectancy of the stack. Temperature distributions within the stack depend on many variables, including non-uniform heat generation, fluid properties and flow quality, fuel cell geometry, and the configuration of cooling plates between the cells. To arrive at a suitable design, engineers may resort to numerous prototype build-and-test cycles that are lengthy and costly — Thermal model of a four-cell stack was created with not to mention how they stifle innovation — because of the coolant flow and convective heat transfer modeled with pipe elements. Pipes also were used to model prohibitive time and expense of evaluating new ideas and thermal contribution of air and hydrogen flow. what-if scenarios. These limitations can be alleviated somewhat with “deterministic” computer-aided engineering (CAE) methods that perform a series of individual analyses. Even in this scenario, engineers must run hundreds or even thousands of individual simulations to arrive at a satisfactory design.Structural analysis and shape optimization of the fuel cell end-plates were performed to optimize the stiffness within space limitations.s6 ANSYS Advantage • Volume I, Issue 3, 2007 www.ansys.com
  21. 21. ENVIRONMENTAL DESIGN: POWER GENERATION 8.55E+1 8.25E+1 7.31E+1 7.30E+1 8.00E+1 7.28E+1 MAXT_FIN MAXT_TFIN 7.27E+1 7.75E+1 7.26E+1 7.50E+1 7.24 5.0 E+1 0E 4.3 -3 0E E-3 3.6 -3 2.00 E-3 0E 7.25E+1 2.9 -3 2.80 E-3 0E 3.60 -3 E-3 2.2 FIN 0E 7.07E+1 4.40 E-3 _T 1.5 -3 1.24E+1 2.50E+2 5.00E+2 7.50E+2 1.00E+3 1.25E+3 1.59E+3 DS_ DS 5.20 0E E-3 TBA -3 DS_DP SE 6.00 Response surfaces show the relationship between multiple variables, After generating 10,000 virtual experiments, engineers create a scatter plot of in this case visualizing the impact of fin thickness and base thickness performance requirements showing maximum temperature versus pressure drop. on the maximum temperature of a cell stack. Dark blue squares represent data points that meet all design requirements and have minimal temperatures. A more efficient way to optimize a design with many reflected real-world stack geometry and non-uniform heatvariables and uncertainty is to account for variation using generation in the membrane. ANSYS DesignXploreradvanced computational and probabilistic tools early in the technology was used for design space exploration anddesign process. This approach is being used extensively probabilistic design methods. Classical design of experi-on research for market-viable alternative energy solutions. ments techniques integrated with the model were used toIn some of this leading-edge work, the ANSYS Workbench define response surfaces and perform sensitivity and trade-platform and ANSYS DesignXplorer software have been off studies on heat generation rates, heat-sink fin geometry,implemented for performing design of experiments in fluid flow, bipolar plate channel geometry, fluid propertiesaccounting for uncertainty and variation in materials, and plate thermal material properties. A Taguchi screeningmanufacturing and load conditions. Simulation tools study was used to identify the most sensitive input para-also are used to streamline laboratory experiments by meters; robust design was used to understand the impactnumerically evaluating the design space to assess and of variation on thermal performance.determine which variables have the largest impact on Researchers at Advanced Engineering Solutions thenresults. Laboratory tests validate the results and are fed used the ANSYS thermal model to develop an alternativeback into the model to improve its predictive capabilities. coolant flow path design that yielded improved thermal In one project studying fuel cell design, the engineering performance. The team found that this approach shavedconsulting firm Advanced Engineering Solutions, based in months off the development process and led to innovativethe United States, used an approach that was aimed at designs through improved understanding of fuel cellestablishing optimal design methodologies for fuel cells. behavior, especially the impact of a wide range ofThe company also was charged with improving product design variables. ■development time and costs by reducing the number ofphysical prototypes and laboratory tests required. In one Referencescase in particular, the research team used tools from [1] Vlahinos, A.; Kelly, K.; Mease, K.; Stathopoulos J., “Shape OptimizationANSYS to develop a fuel cell stack thermal modeling of Fuel Cell Molded-On Gaskets for Robust Sealing,” ASME paperprocess to assess design sensitivity on fuel cell thermal Fuelcell2006-97106, 2006 International Conference on Fuel Cellperformance. The models were used to evaluate new Science, Engineering and Technology, Irvine, CA June 19–21, 2006.cooling plate flow paths and to assist in the development [2] Kelly, K.; Pacifico, G.; Penev, M.; Vlahinos A., “Robust Designof improved heat transfer characteristics. Techniques for Evaluating Fuel Cell Thermal Performance,” ASME paper The thermal modeling process incorporated an ANSYS Fuelcell2006-97011, 2006 International Conference on Fuel CellMechanical 3-D multi-cell stack thermal model that Science, Engineering and Technology, Irvine, CA June 19–21, 2006.www.ansys.com ANSYS Advantage • Volume I, Issue 3, 2007 s7
  22. 22. ENVIRONMENTAL DESIGN: POWER GENERATIONMaking Electricitythrough ChemistryAnalysis helps power fuel cell design.By Laura Ambit and Esther Chacón, Instituto Nacional de Tecnica Aeroespacial, Madrid, Spain PEM fuel cellMonica Pardo and Eva Novillo, Compañía Española de Sistemas Aeronáuticos, Madrid, Spain Fuel cells are electrochemical devices that produce operating conditions affect the cell’s performance. The per-electricity from an external supply of fuel and oxidant. Many formance depends on a variety of structural and functionalcombinations of fuel and oxidants are possible; however, parameters, such as the geometry of the flow paths in thethe fuels most often used are hydrogen, hydrocarbons and bipolar plates, along with the humidity, temperature andalcohols, while oxygen typically is the oxidant. The conver- operating pressure. To improve the performance of a PEMsion of the fuel to energy takes place via an electrochemical fuel cell, it is necessary to understand the behavior of vari-reaction in which the only byproducts are water (when ables such as velocity, flow distribution, condensation ofhydrogen is the fuel) and heat. The process is clean, quiet water and current distribution. Numerical simulation thusand highly efficient. For these reasons, fuel cells are highly becomes an important tool for understanding the physicalregarded in the search for sustainable energy sources. phenomena that take place. There are several types of fuel cells, and their differ- The work at INTA and CESA set out to utilize the fuelences are dependent on the nature of the electrolyte. cell module of FLUENT computational fluid dynamicsPolymer electrolyte membrane (PEM) fuel cells operate at (CFD) software to capture the fundamental processes of thelower temperatures than other types, can supply up to 10 W fuel cell and to optimize the flow path design of the bipolarof power per cell and can be stacked to handle higher plates to improve efficiency. To achieve these objectives,power loads. The principal applications of PEM fuel cells are a number of simulations were carried out, ranging fromin transportation — some experts believe fuel cells will revo- the simplest models of fluid flow analysis to more complexlutionize the automotive industry — and decentralized ones that included modeling electrochemistry andstationary electrical applications, which range from powering multiphase flow.home co-generation systems to vacuum cleaners and The simulations were conducted using both a commer-notebook computers. cial geometry with parallel channels and a prototype In work done by the Instituto Nacional de Tecnica geometry with two serpentine path flow channels. TheAeroespacial (INTA) and Compañia Española de Sistemas effect of operating conditions such as inlet flow humidity,Aeronáuticos (CESA) in Madrid, Spain, researchers chose to mass flow rate and the influence of geometric parametersmodel a single 7 W PEM fuel cell with the intent of under- such as channel width also were studied in a simplifiedstanding how different geometric configurations and model of a single serpentine channel. Contours of the mass fraction of water within the anode (left) and cathode (right) channels for a commercial parallel geometry PEM fuel cells8 ANSYS Advantage • Volume I, Issue 3, 2007 www.ansys.com

×