Computational Fluid Dynamics

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3 Simulation Driven Product Development Key Business Value Findings Best-in-class manufacturers who hit their revenue, cost, launch date and quality targets 86% of the time, also: Use simulation in the design phase Get to market 158 days earlier* Average 1.6 fewer physical prototypes Save $1.9M in development costs* * for complex products - Aberdeen Group, 2008 Automotive Aerospace Defense Electronic Equipment Manufacturing Energy Process 2010 ANSYS, Inc. All rights reserved. 3 ANSYS, Inc. Proprietary

4 Cost Effective Innovation Voith Turbo reduces costs while developing quiet fans by simulating a complete railcar cooling system. Brose uses simulation to drive product quality, reduce testing and minimize costs. Optimizing a seemingly simple electrical switch device assembly through simulation saves time and reduces costs for Schneider Schneider switch device assembly. Time to market cut by 40%; cost reduced by 30% Brose door panel: By using simulation, we have been able to reduce one specific door system s mass by approximately 50 percent Voith SilentVent : developing a single prototype fan for an existing cooling system through simulation can reduce costs by two-thirds 2010 ANSYS, Inc. All rights reserved. 4 ANSYS, Inc. Proprietary

5 Aberdeen Survey 2010 Business Drivers Top business pressures driving product design improvement: Customer demand for lower cost products Shortened product development schedules Competitive pressures to differentiate with better quality/reliability Need for greater innovation for new market opportunities Competitibe pressures to differentiate with smarter/feature rich products 0% 10% 20% 30% 40% 50% 60% 16% 22% 26% 45% 50% Biggest hurdles for product design: Problems/errors found too late Making trade-off for cost, performance, and quality Frequent design changes Predicting product behavior in a real world environment Workforce reductions/lack of technical experts 0% 10% 20% 30% 40% 50% 47% 41% 36% 28% 24% 2010 ANSYS, Inc. All rights reserved. 5 ANSYS, Inc. Proprietary

6 Best-in-Class Companies Good Practices Strategies to improve product design: Analyze product behavior earlier 56% 70% Implement a 'get it right the first time' strategy 39% 67% Promote collaboration between analysis experts / design engineers 38% 52% Evaluate more design iterations in the concept/ design stage 43% 52% Define best practices for assessing product behavior 36% 49% Reduce number of unique parts in product 34% 42% Best-in-Class All Others 2010 ANSYS, Inc. All rights reserved. 6 ANSYS, Inc. Proprietary

7 Simulation Intensity When Simulation is Used? 60% 50% 40% 30% 20% 10% 0% 28% 49% Occasionally, 1-3 times during the design process Best-in-Class 48% 16% Systematically, regular intervals throughout design process All Others This is the biggest difference between Bestin-Class companies and all others! 2010 ANSYS, Inc. All rights reserved. 7 ANSYS, Inc. Proprietary

8 Technology Used by Best-in-Class Technical Capabilities Used by Best-in-Class 0% 20% 40% 60% Optimization/behavioral modeling Material properties library/database Control over meshing elements for simulation Automatic meshing for simulations 27% 35% 35% 45% 67% 61% 61% 55% Best-in-Class All Others 2010 ANSYS, Inc. All rights reserved. 8 ANSYS, Inc. Proprietary

9 Survey in a Nutshell Companies want to minimize cost, time to market and risk Successful companies have a Get it Right the First Time strategy Analyze product behavior earlier to identify errors and problems early in the process Use simulation systematically Progressively fine tune and validate their model to get accurate predictions Perform optimization to make the best trade-off for cost, performance and quality 2010 ANSYS, Inc. All rights reserved. 9 ANSYS, Inc. Proprietary

10 Simulation Driven Product Development: Early Adopters Honeywell Velocity Product Development (VPD tm ) BMW - Simulation Driven Product Development Parker Winovation Innovation Strategy P&G ACCELERATE 2 Drive Innovation 2010 ANSYS, Inc. All rights reserved. 10 ANSYS, Inc. Proprietary

16 In-Depth Technology Spanning Multiple Domains Technical Breadth Meshing Tet/Prism Hex/Hex Core Structured Unstructured Multi-zone Body-fitted Cartesian Patch Independent More Technical Depth Structural Large Displacements Finite Strain Contact Multibody Dynamics Random Vibration Implicit & Explicit Fluids Compressible Incompressible Laminar Flow Conduction Thermal Convection Radiation Phase Change Mass Transport Electromagnetics Quasi static (Low Freq) Full Wave Joule Heating More Turbulence Multiphase Flow Non-Newtonian Fluids More More Eddy currents Current flow Circuit Coupling More Steady-State, Transient, Harmonic & Modal Linear & Nonlinear 2010 ANSYS, Inc. All rights reserved. 16 ANSYS, Inc. Proprietary

19 CFD - Funktionsprinzip Erstellung des Geometriemodells Erzeugung eines Rechengitters Vergabe von Randbedingungen Mischung Wasser v = 10 m/s Korrosive Substanz v = 3 m/s 2010 ANSYS, Inc. All rights reserved. 19 ANSYS, Inc. Proprietary

20 CFD - Funktionsprinzip Ausführung der Strömungsberechnung Analyse des Strömungsfeldes Überprüfung des Designs Volumenanteil der korrosiven Substanz 2010 ANSYS, Inc. All rights reserved. 20 ANSYS, Inc. Proprietary

23 2010 ANSYS, Inc. All rights reserved. 23 ANSYS, Inc. Proprietary Navier-Stokes-Gleichungen j i i j j k j k j j i j j i i k k j j k j k j B x x u x p x u u t u B x u x u x x u x x p x u u t u 2 kosität Volumenvis keine konstant, und Inkompress ibles Fluid, für kompressib les Fluid - Gleichung -Stokes Navier Impulserhaltung

24 2010 ANSYS, Inc. All rights reserved. 24 ANSYS, Inc. Proprietary Energieerhaltung h j ij j j j k k k k S u J h x T k x p E u x t E Zustandsgleichung ), ( T P T C C T k k T p p ) ( Beziehung für Stoffwerte 0 k k u x t Massenerhaltung Erhaltungsgleichungen

25 Turbulenz-Modellierung Turbulenz stellt einen durch chaotische Fluidbewegungen charakterisierten Strömungszustand dar. Turbulenz ist ein instationäres Phänomen Die Navier-Stokes-Gleichungen können zur direkten Simulation einer turbulenten Strömung verwendet werden, aber Zeit- und Raumskalen der Turbulenz sind im Verhältnis zum durchströmten Volumen äußerst klein! Skala der kleinsten turbulenten Wirbel ist ca mal kleiner als die Skala des Volumens. Wenn 10 Knotenpunkte zur räumlichen Auflösung eines turbulenten Wirbels benötigt werden, so werden Knotenpunkte für die Auflösung eines cm 3 benötigt! Knotenpunkte benötigen ca. 1 GB RAM Berechnung einer instationären Strömung diskretisiert mit einer großen Anzahl Knotenpunkte ist äußerst rechenzeitintensiv Beispiel Raumluftströmung: 0,2 mm Kantenlänge; Zeitschritt ca. 1e-5 s 2010 ANSYS, Inc. All rights reserved. 25 ANSYS, Inc. Proprietary

26 Lösungsmethoden - Bestandteile Diskretisierung des Berechnungsgebietes (Gitter) Lösung der algebraischen Gleichungen CFD Lösungsmethoden Diskretisierung der Gleichungen Behandlung der konvektiven Terme und der Quellterme 2010 ANSYS, Inc. All rights reserved. 26 ANSYS, Inc. Proprietary

27 Diskretisierung des Volumens Transformation des physikalischen Modells in eine numerisch lösbare Form, kann als Diskretisierung des Volumens bezeichnet werden. einzelne Zellen kontinuierliches Volumen diskretisiertes Volumen 2010 ANSYS, Inc. All rights reserved. 27 ANSYS, Inc. Proprietary

29 Voraussetzungen Erfolgreicher Einsatz von CFD im Unternehmen beruht auf Leistungsfähiger Software Leistungsfähiger Hardware Kompetenten Anwendern oder / und Kompetenten externen Partner Management Commitment CFD enabled Company 2010 ANSYS, Inc. All rights reserved. 29 ANSYS, Inc. Proprietary

32 Circulating Fluidized Bed Circulating fluidized beds consist of a cyclone, downcomer, riser, numerous inlets, and a single outlet (red) They contain a circulating mixture of gas and solids Different processes clean or burn the solids The Eulerian granular multiphase model in FLUENT is used to simulate the multiphase flow in a typical unit 2010 ANSYS, Inc. All rights reserved. 32 ANSYS, Inc. Proprietary

33 Circulating Fluidized Bed (contd..) An unstructured mesh of 74,000 cells is used Solids occupy 7% by volume, have a diameter of 85 m, and density of 2200 kg/m 3 The solids concentration remains constant during operation Air enters through several inlets and is exhausted out the top 2010 ANSYS, Inc. All rights reserved. 33 ANSYS, Inc. Proprietary

34 Circulating Fluidized Bed (contd..) Path lines (colored by air velocity magnitude) show the motion of air. Up the riser Through the connecting channel Spinning in the cyclone Exiting through the outlet Some air falls through the downcomer and is recirculated with the solids 2010 ANSYS, Inc. All rights reserved. 34 ANSYS, Inc. Proprietary

35 Circulating Fluidized Bed (contd..) Solids volume fraction on the walls of the unit show Maximum concentration at the base of the cyclone, after separation High concentration throughout the downcomer Weak but uniform concentration in the riser due to upward-angled inlets positioned along the riser walls Flow field is consistent with expect- ations and reports in the literature Results suggest the FLUENT 6.0 Eulerian multiphase model is well suited for this application 2010 ANSYS, Inc. All rights reserved. 35 ANSYS, Inc. Proprietary

36 Gesamtansicht Austritt Gas und kleine Partikel über Tauchrohr In freie Umgebung Eintritt Partikel Dichte kg/m3 85 t/h entspricht 23,611 kg/s 5e-3m bis 5e-4m v = 0 m/s Gaseintritt m 3 N/h entspricht v = 25,756 m/s T = 450 C m 3 /h Medium: Luft 2010 ANSYS, Inc. All rights reserved. 36 ANSYS, Inc. Proprietary

39 Anströmung von Komponenten - Filter Die Simulation zeigt den Einfluß von Umlenkblechen auf die Anströmung des Filters -> Erhöhung von Standzeiten 2010 ANSYS, Inc. All rights reserved. 40 ANSYS, Inc. Proprietary

40 Anströmung von Komponenten - Wärmeübertrager heißer Gasstrom Rohrbündel- Pakete Gasauslaß Courtesy of SMC (Sistemi di Misura e Controllo), Pisa, Italy 2010 ANSYS, Inc. All rights reserved. 41 ANSYS, Inc. Proprietary

41 Anströmung von Komponenten - Wärmeübertrager Originaldesign Strömungsgeschwindigkeit Dargestellt sind Konturen der Strömungsgeschwindigkeit (blau = niedrig, rot = hoch) Strömungs- Ungleichverteilung im 3. Wärmeübertragermodul führt zu einer erheblichen Verringerung des Gesamt- Wirkungsgrades Rohrbündel Courtesy of SMC (Sistemi di Misura e Controllo), Pisa, Italy 2010 ANSYS, Inc. All rights reserved. 42 ANSYS, Inc. Proprietary

42 Anströmung von Komponenten - Wärmeübertrager Modifikation 1 Einbau eines Leitbleches am Ende der Rohrbündel führt zu einer erheblichen Verbesserung in der Geschwindigkeitsverteilung Strömungsgeschwindigkeit Rohrbündel Courtesy of SMC (Sistemi di Misura e Controllo), Pisa, Italy 2010 ANSYS, Inc. All rights reserved. 43 ANSYS, Inc. Proprietary

43 Anströmung von Komponenten - Wärmeübertrager Modifikation 2 mit fünf Leitblechen führt zu einer noch besseren Strömungsverteilung bei reduziertem Druckverlust gegenüber Modifikation 1 -> massive Erhöhung des Wirkungsgrades Courtesy of SMC (Sistemi di Misura e Controllo), Pisa, Italy 2010 ANSYS, Inc. All rights reserved. 44 ANSYS, Inc. Proprietary

44 Rohrreaktor - Kühlung dominiert Ausbeute Auslaß des Kühlmediums sehr starke Ungleichverteilung der Umsetzungsraten in den Einzelrohren ca Einzelrohre stark exotherme Reaktion Einlaß für Kühlmedium 20 Bohrungen über den Umfang verteilt 2010 ANSYS, Inc. All rights reserved. 45 ANSYS, Inc. Proprietary

48 Mixing of Materials Why do mixing analysis? flow patterns Mixing index/efficiency designing, optimizing, and troubleshooting mixing devices The techniques could be different Electric / magnetic mixing for metal Batch mixer/stirred tanks Continuous mixer (TSE) Static mixers Examples in Building Product Industry Mixing of Cement/Gypsum/Plaster 2010 ANSYS, Inc. All rights reserved. 49 ANSYS, Inc. Proprietary

49 High Viscosity Fluid Mixing Reduce experimentation Reduce time-to-market by reducing total number of physical experiments Answer for what-ifs Fluid properties Feed rate Geometry Impeller type, speed, number Baffles Dip-tube locations "Engineers who scoffed at CFD analysis a year and a half ago now prefer that design changes be evaluated using CFD before being tried in the field. Computer simulation using Fluent's CFD software made it possible to triple the efficiency of equipment design engineers, while improving quality of our product." - Phil Staples, DuPont 2010 ANSYS, Inc. All rights reserved. 50 ANSYS, Inc. Proprietary

50 Optimization of Impeller Placement Original design Optimized design What is so obvious with CFD sometimes takes forever to figure out in the plant! Reducing the gap between the impellers establish thorough overall mixing But, this is just one of many scenarios where CFD can provide much greater insight than conventional pilot / plant trials 2010 ANSYS, Inc. All rights reserved. 51 ANSYS, Inc. Proprietary

53 Cracking Furnace Optimization Process Tubes K Key Parameters Heat Transfer to process tubes Control of tube temperatures Pollutant (NO x ) reduction Suspected that staged low-no x burners would have flame roll-over Modeling included flow and reaction in process tubes to get accurate tube temperatures Initial concerns confirmed Optimization included changes in wall inlet angles and floor burner placement New design is up and running, performing as advertised at enduser site Original Burners Initial Ultra-Low NOx Design K Courtesy ABB Lummus Global Original Burners Improved Ultra-Low NOx Design 2010 ANSYS, Inc. All rights reserved. 54 ANSYS, Inc. Proprietary

54 Schlußfolgerung CFD ist ein mächtiges Werkzeug zur Simulation von Strömungen, Wärmeübertragung und verwandten Phänomenen für ein weites Anwendungsspektrum in der Forschung und bei ingenieurtechnischen Problemstellungen. Kosten für CFD-Analysen sind in den letzten Jahren massiv gesunken Leistungsfähigkeit der Rechner nimmt kontinuierlich zu Anschaffungskosten für Rechner sinken Einfach zu bedienende CFD-Programme vorhanden Automatische Netzgenerierung Grafische Benutzeroberflächen Leistungsfähiges Post-Processing Kompetente Anwender / Partner sind Grundvoraussetzung Einführung einer Get it right the first time Strategie 2010 ANSYS, Inc. All rights reserved. 55 ANSYS, Inc. Proprietary