Vehicle Applications using STAR-CCM+ Frederick J. Ross Director, - - PowerPoint PPT Presentation

Vehicle Applications using STAR-CCM+

Frederick J. Ross Director, Ground Transportation

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.

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

2012 Key Advances in STAR-CCM+ for Ground Transportation

New Retention Code Old Retention Code

Surface Wrapper: Improved Geometry Retention

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.

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.

Accelerating erating Converge ergence: nce: Couple pled d Solv lver er

Coup uple le solver er has really ly been een pus ushed ed hard d over r the e past yea ear r by our ur F1 teams ms

– 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.

Couple: 6 Yaw Segregated: 6 Yaw Couple: 0 Yaw Segregated: 0 Yaw

7.67 13.36 2.22 5.29

Elapsed Time (Hours)

64 Cores

Couple: Grid 2 Segregated: Grid 2 Segregated: Grid 1

2.7 9.5 11.3

Elapsed Time (Hours)

64 Cores

STAR-CCM+ improvements now show time reduction for passenger cars as well as commercial vehicles.

Optimate: Design Exploration Mode Forms Response Surfaces

There has been increase in demand for DOE studies. In 2012, CD-adapco came

• ut with new license plan to be more flexible for DOE studies. Included is also
• ptimization tool within STAR-CCM+ to simplify the process.

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.

Water er/Dir /Dirt t Managemen gement

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

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.

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.

SCR R Devices es

• 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+.

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.

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.

Key applications where clients are taking advantage of virtual simulation in 2012.

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.

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
• 20-30 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 1/10th the computation time.

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.

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 vibro- acoustic and propagation of noise into the cabin.

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.

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.

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

• 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

Vehicle Thermal Management (VTM): Front End Cooling

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.

• 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

Key Feature: Enabling Quick Turn-Around

Pre-processing is a key advantage of STAR-CCM+. Clients are finding pre-processing tools time savings up to 70% of their previous process

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.

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
• ver 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.

User has different

• ptions 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.

Autom

• mat

ation ion: : Generati erating ng Pa Part t Conta tact ct

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.

Example showing different methods

Indirect Mapped Interface Conformal CAD imprinted

CAD quality of PowerTrain has improved over the years, and can be directly used. Indirect mapped interface used to map environment around PowerTrain components.

• 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.

Exam ample ple Imp mpor

• rtin

ting g CHT T Geome metr try EGR R Cooler ler

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.

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+

• These features, with existing physics in

STAR-CCM+ allow thermal, electromagnetic, and structural analysis all in a single run.

Liebherr T 282B: Hybrid Diesel-Electric 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.

Validation on Module Level

Comparison of measured and simulated results

Temperature plots for two cells of the stack , ΔTmax=2°C Averaged cell voltage , ΔUmax=80mV Heat transported by coolant

Lithi thium um ion Batt tter ery y Simulation mulation

Courtesy of ASCS Validation, Stuttgart, Germany

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

Coupled Vehicle Thermal Analysis

Thermal Solution Radtherm

Conduction + Radiation

Underhood Flow Solution STAR-CCM+

Air ir Side Side BC HT HTC, , Air ir Temp emp Meta etal l Temp emps 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.

VTM Co-Simulation for Key-Off Simulation

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

Solid Solid Solid Solid Fluid Fluid Fluid Fluid

F*

modified conditions

Fluid Solid

1 time step

Steady ady Implicit icit Unsteady eady Steady ady Steady ady

etc.

Steady State Phase Unsteady Phase

Solid

1 time step

Fluid Solid

1 time step

September 20, 2012 Page 32

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.

Analysis Paths

Page 33 September 20, 2012

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.

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

Air Bubble Entrapment and Liquid Drain

Captured Air bubbles shown below surface Poorly drained liquid captured above the surface

Bath Surface

Paint dipping and e-coating are being done by several major EOM’s.

• 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

Casting Simulations in the Automotive Industry I

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.

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

Clients are getting more out of their virtual simulation.

– Building complex assemblies

• f 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

Mark rket t Tren end: : Looking king to Model l More e Physics sics

Engine manufacturers are looking for more complete engine simulation. These simulations include fluid/oil, as well as operating environment to improve engine design.

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.

• 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

Summary