Vehicle Applications using STAR-CCM+ Frederick J. Ross Director, Ground Transportation

Transcription

1 Vehicle Applications using STAR-CCM+ Frederick J. Ross Director, Ground Transportation

2 Agenda 2012: Great Year for Advance Vehicle Simulation This presentation will be broken down to two parts: Key features/enhancements of STAR-CCM+ which are impacting ground transportation sector Key applications where clients are taking advantage of virtual simulation in 2012.

3 2012 Key Advances in STAR-CCM+ for Ground Transportation Meshing Improved geometry retention with surface wrapping Indirect mapped interface Geometry transfer from CAD Physics Coupled Solver Continuity convergence accelerator Overset grids Wall Film model Boiling, Melting Solidification Discrete Element Modeling (DEM) Co-Simulation Conduction Baffles Posting LIC

4 Surface Wrapper: Improved Geometry Retention New Retention Code Old Retention Code V7.06 Introduces improved geometry retention from the surface wrapper. This allows the surface wrapper to move deeper into sharp corners. Studies with this features have shown improved convergence.

5 Indirect Mapped Interface Indirect Mapped Interface Indirect mapped interfaces have been used for years to map between CFD and FEA tools. Now, provided as a boundary type in STAR-CCM+ simplifies joining complex environment around solid components.

6 Accelerating Convergence: Coupled Solver Elapsed Time (Hours) 64 Cores Elapsed Time (Hours) 64 Cores Segregated: Grid 1 Segregated: Grid 2 Couple: Grid Segregated: 0 Yaw Couple: 0 Yaw Segregated: 6 Yaw Couple: 6 Yaw Couple solver has really been pushed hard over the past year by our F1 teams F1 Teams are regulated on amount of CFD/Wind Tunnel Time used Coupled solver has allowed teams reduce computational costs by 25%. This allows more calculations per year. STAR-CCM+ improvements now show time reduction for passenger cars as well as commercial vehicles.

7 Optimate: Design Exploration Mode Forms Response Surfaces There has been increase in demand for DOE studies. In 2012, CD-adapco came out with new license plan to be more flexible for DOE studies. Included is also optimization tool within STAR-CCM+ to simplify the process.

8 Overset Grids 2012 Introduced the new feature of overset grids. This helps simplify moving complex paths or motion such as pumps, vehicle handling, or passing.

9 Water/Dirt Management Wall film model allows water to be tracked on surface. Body forces added to simulate motion of windshield wipers New wall film models are also helping improve DeIce/DeFog simulations Head Lamp Defogging

10 Spray Freezing on Windshield Liquid film solidification has also been implemented and is currently undergoing extensive testing... Example: Freezing of a liquid film created by water droplets hitting a cold windshield Wall Film includes ability of phase change. The above example shows ice building up on the windshield as particles impact on the cold surface.

11 Modeling of Cabin Deice/Defog Deicing/Defogging modeling in STAR-CCM+ Thin Film Model Defog dependent on coefficients DeIce not valid for low ambient temperatures 2012: Wall Film Model Provides more physics based model for both deice and Defog Water film model now can model physics of condensation, melting, and solidification. The enhanced physics improves accuracy for cases with low ambient temperatures.

12 SCR Devices V7.06 Adds boiling to wall film SCR are commonly found in Off- Highway, Commercial Vehicles, and Automobiles Latest release of wall film includes condensation and boiling. These are needed components in modeling SCR devices within STAR-CCM+.

13 Discrete Element Method (DEM) Advance Fluid-Particle interaction Particles can simulate: Dirt Particles Grass Clumping on Lawn Mowers Corn Husks Snow Flakes Sand Particles can bounce or stick or even break apart. Circular or composite particles DEM has been pushed heavily by off-highway vehicles. Enhancements in 2012 enable to model millions of particle fully coupled to CFD simulation in a reasonable time frame.

14 Vector Option: LIC Added features are being developed for post processing. There is now simh to store results for iteration or time step. New graphics options such as LIC vector style. Plots shown with Vortex core tracking from v6.

15 Key applications where clients are taking advantage of virtual simulation in Ground Transportation covers wide range of applications. STAR-CCM+ has grown in use for each of these individual groups. This next section highlights some of the recent work.

16 Impacting Design: Aerodynamic Optimization Ford has shown recently a process for rapid aerodynamics at a recent workshop Evaluate response surfaces to determine optimum design. Compared both steady to unsteady simulation Unsteady solution took 10 times longer Turn-Around: 200 cases per week Steady Solver million cells 500 processor cluster ANSA STAR- CCM+ PowerPoint DOE study compared steady simulation to transient. With steady simulation, the client was able to form the same response surface as predicted by transient, but in 1/10 th the computation time.

17 Trend: Increase of Transient Simulation Simulating Transient Operating Conditions In 2012, there has also been increase in demand, and testing looking at transient aerodynamics. Some work looks at transient operating conditions, such as passing or vehicle cornering.

18 Growth in Aero-acoustic Key Areas of Interest Aero-Vibroacoustics Internal Flow HVAC Ducts Fans Pumps Over the past year, emphasis of aero-acoustic study has shifted from far field propagation to vibroacoustic and propagation of noise into the cabin.

19 Example Unsteady Simulation: Fluid Solid Interaction Roof Deflector This is an example where it is important to run the mesh morpher as part of the unsteady analysis. Displacement exaggerated for animation Displacement can be calculated coupled to stress code, or using internal stress solver of STAR-CCM+ Fluid solid interaction key use for unsteady simulation.

20 Water/Dirt Management Transient DES simulation tracking water particles on side of vehicle. Water particles leave wheel region, tracked with wall film model on vehicle surface. Also looking at exhaust gas mixing in vehicle wake to find regions Exhaust gas trapped in wake of vehicle is drawn into vehicle through air vents. Combining DES with fluid particles in wake provide more realistic soiling on rear and sides of the vehicle.

21 Ground Transportation External Aerodynamic Environmental Conditions Water/Dirt Management Vehicle Thermal Management Front End Cooling/Top Tank Temperature Component Temperature Prediction Cabin Simulations Physiological Models Defrost/Demist analysis Manufacturing Simulations Paint Dipping E-coat Powertrain Intake/Exhaust SCR Catalyst System

22 Vehicle Thermal Management (VTM): Front End Cooling Cooling air flow: Heat Exchanger Sizing/Positioning Top Tank Temperature Prediction Models secondary flow for CAC and radiator. Fan Simulation Body Force Method Pressure Jump Multi-Reference Frame Rigid Body Motion CD-adapco has over 20 years experience looking at vehicle heat protection. With STAR-CCM+, front end cooling has been made easy. Users are achieving results within 24 hours.

23 Key Feature: Enabling Quick Turn-Around STAR-CCM+ builds all tools in a single environment Grid generation in STAR-CCM+ designed as pipeline process. Designed to enable quick modifications Environment promotes automation Record button on GUI helps quickly build automation Pre-processing is a key advantage of STAR-CCM+. Clients are finding pre-processing tools time savings up to 70% of their previous process

24 Example: Tractor Done several demo s by Pre- Sales on off-highway vehicles CAD: ProE Baseline Study: 7 days Replace component 1 day Swap geometry: 10 minutes Analysis: 10 Hours Post Processing: 0.5 hours Output: Coolant top tank temperature Temperature field Flow field Case goes straight from ProE to STAR-CCM+. Surface wrapping enables automation of case setup. Modifications just a swap of part.

25 CAD to Solution in 1 Day CD-adapco worked with Off Highway Client to automated process Model Preparation: ProE All boundaries names are marked in ProE model. Surface exported straight from STAR-CCM+ Head nodes generate mesh Once done, job pushed straight over to cluster Post processing done at end of run on cluster Returns PowerPoint with results. Process is completely automatic. Modifications can easily be done by exporting new surface, or just swapping CAD file.

26 Automation: Generating Part Contact User has different options to form part contacts: 1. Build part contacts in CAD 2. User boolean operation in STAR-CCM+ CAD module 3. Imprint triangulated surface in surface repair module 4. Mesh separate, use solver to arbitrary match surfaces Indirect mapped interface or direct. One of the strengths of STAR-CCM+ is in building CHT assemblies for complex geometry. This includes both modeling of the solids, as well as fluid around the object.

27 Example showing different methods Conformal CAD imprinted Indirect Mapped Interface CAD quality of PowerTrain has improved over the years, and can be directly used. Indirect mapped interface used to map environment around PowerTrain components.

28 Example Importing CHT Geometry EGR Cooler EGR cooler includes model of coolant, exhaust, and structure. CAD geometry came in clean, fluid extraction could be used to generated dual fluid streams. Easy model to setup in a day. Example shows complex multi-fluid cooler which can be modeled easily in a day due to clean CAD geometry. Modifications are even easier since just require part replacement, and no additional manual work.

29 Hybrids and Electric Vehicles With collaboration with Battery Design LLC, STAR-CCM+ has a unique working methodology for the analysis of electro chemical and thermal performance of lithium-ion battery cells, modules and pack installations. Electromagnetic capabilities are also being developed in STAR-CCM+ Liebherr T 282B: Hybrid Diesel-Electric These features, with existing physics in STAR-CCM+ allow thermal, electromagnetic, and structural analysis all in a single run. Hybrids and Electric Vehicles are growing in demand. Design of electrical motors and battery packs are growing. Not only modeling the motor designs is important, but the thermal environment is critical for peak performance.

30 Lithium ion Battery Simulation Validation on Module Level Comparison of measured and simulated results Temperature plots for two cells of the stack, ΔT max =2 C Heat transported by coolant Averaged cell voltage, ΔU max =80mV slide shows a single analysis within STAR-CCM+ where a complex heat path is resolved, including convection and condition, to capture the effect of a cooling system upon a set of lithium ion cells which are electrically loaded. Both the thermal and electrochemical response of this system are solved within STAR-CCM+ and presented alongside test work Courtesy of ASCS Validation, Stuttgart, Germany

31 Coupled Vehicle Thermal Analysis Thermal Solution Radtherm Conduction + Radiation Air Side BC HTC, Air Temp Metal Temps Underhood Flow Solution STAR-CCM+ STAR-CCM+ links to 1D codes such as GT Power. It also links with third party codes such as Radtherm or FEA Codes. Enables calculations such as fluid solid interactions.

32 Unsteady Phase Steady State Phase VTM Co-Simulation for Key-Off Simulation Steady Solid Solid Solid Steady Fluid Fluid Fluid Analysis of the thermal behavior of a key-off event without having to solve the fluid flow field updates transiently. Use of larger time-steps, which results in quicker turnaround time. For a key-off event, modified steady state flow case is run (F*) without speed prior to running the unsteady phase. An appropriate time step may be set as high as 30 seconds, but may need to be smaller based on the applied loads Fluid Solid Implicit Unsteady Solid 1 time step F* modified conditions Steady Fluid Solid 1 time step Solid 1 time step etc. Fluid Co-Simulation offers an efficient method for modeling long thermal cycle simulation such as Key-Off simulation. The solids capture the transient cool down behavior, as the fluid states are updated to a new steady state condition. September 20, 2012 Page 32

33 Analysis Paths Analysis paths can be tailored to suit your needs. Key-Off after steady uphill trailer tow is one critical operating condition. More complex modes are being examined to look at peak thermal loads for key operating conditions. September 20, 2012 Page 33

34 Ground Transportation External Aerodynamic Environmental Conditions Water/Dirt Management Vehicle Thermal Management Front End Cooling/Top Tank Temperature Component Temperature Prediction Cabin Simulations Physiological Models Defrost/Demist analysis Manufacturing Simulations Paint Dipping E-coat Powertrain Intake/Exhaust SCR Catalyst System

35 Air Bubble Entrapment and Liquid Drain Poorly drained liquid captured above the surface Bath Surface Captured Air bubbles shown below surface Paint dipping and e-coating are being done by several major EOM s.

36 Casting Simulations in the Automotive Industry I Sand casting of AlMg10 flange for automotive gear box Casted by Ohm & Hähner Germany Casting in foundry shows cold runs Simulation deployed to analyze/ redesign pouring/ gating system Cast before process optimization Simulation result after redesign of gating system Casting is another growing are for simulation. Example above shows the initial casting failure. CFD simulation was used to help redesign gating system.

37 Ground Transportation External Aerodynamic Environmental Conditions Water/Dirt Management Vehicle Thermal Management Front End Cooling/Top Tank Temperature Component Temperature Prediction Cabin Simulations Physiological Models Defrost/Demist analysis Manufacturing Simulations Paint Dipping E-coat Powertrain Intake/Exhaust SCR Catalyst System

38 Market Trend: Looking to Model More Physics Clients are getting more out of their virtual simulation. Building complex assemblies of complete engine Looking at coolant, oil flow, exhaust and induction system Studying thermal loads on engine, as well as peak thermal stresses Studying where boiling occurs Engine manufacturers are looking for more complete engine simulation. These simulations include fluid/oil, as well as operating environment to improve engine design.

39 Vehicle Thermal Protection As tools get easier to use, the more can be done with simulation. Clients are expanding detail included in the model to include not just primary air flow and solids, but also secondary fluid stream such as the air induction system, Coolant flow, Exhaust Flow and Oil Flow. This is a trend CD-adapco is a part of.

40 Summary STAR-CCM+ use in ground transportation is growing quickly Users are finding STAR-CCM+ can reduce turn-around time enabling CFD to impact their engineering design. Environment of STAR-CCM+ leads to automation. Automation helps further reduce turn-around time, and allow engineers to concentrate on design. Simplifies modeling process for complex geometry Development team still placing new features to help existing clients Overset Grids: Ease for grid motion Water Film model: Improved soiling Vibro Acoustics: noise inside the vehicle Shell conduction: Faster/Easier Heat Protection Indirect mapped interfaces: Allows complex CHT cases built in STAR-CCM+ DEM: Particles allowed to interact with flow field Optimization: new license and tools to make optimization easier

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