Vehicle Applications using STAR-CCM+ - Siemens · Vehicle Applications using STAR-CCM+ Frederick J....
Transcript of Vehicle Applications using STAR-CCM+ - Siemens · Vehicle Applications using STAR-CCM+ Frederick J....
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 Convergence: Coupled Solver
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.
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
out with new license plan to be more flexible for DOE studies. Included is also
optimization 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/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
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 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+.
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
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.
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.
Automation: Generating Part Contact
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.
Example Importing CHT Geometry
EGR Cooler
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
Lithium ion Battery Simulation
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 Side BC
HTC, Air Temp
Metal Temps
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
Implicit Unsteady
Steady
Steady
etc.
Ste
ad
y S
tate
Ph
ase
U
nste
ad
y P
ha
se
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
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
Market Trend: Looking to Model More Physics
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