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New VW Fox Defog / Defrost
Air Channel Virtual
Development
Tales Adriano Ferreira
Volkswagen do Brasil
2
Agenda
• “Berechnung” Overview
• Motivations
• Goals
• Problem Description
• Software Tools
• Numerical Model
• Simulation Results
• Air Channel Geometries
• Experimental Results
• Final Remarks
3
“Berechnung” Overview
BIW Stiffness (Static and Dynamic) MSC Nastran
Trimmed Body and Complete Vehicle Sfiffness MSC Fatigue
Pillars Stiffnes Altair Hyperworks
Doors and Lids
Trim Compnents
Chassis Components
Crash ESI Pamcrash
Repairs Cost TNO Madymo
Anchorages
Components Impact tests
Pedestrian Protection
Occupants Simulations / Restraint Systems
Vehicle Dynamics MSC Adams
Wheel Envelopes
"Bodenfreigang"
Door / Lids / Mechanisms Dynamics
Defog / Defrost Ansys Fluent
Air Ducts Flow Distribution
External Aerodynamics
MULTIBODY SIMULATIONS
CFD
DISCIPLINES SOFTWARES
STIFFNES / STRENGTH / DURABILITY
IMPACT / CRASHABILITY
4
Concept / Design
CAD
CAEPrototypes- Construction
Prototypes - Tests
Tests
Manufacture ConceptsProduction Preparation
Toll Fabrication
“ Milestone VP-K” -
Virtual vehicle approval
for development
continuation.
“Berechnung” Overview
Product Development
5
“Berechnung” Overview
CAE procedures are
standardized with
Volkswagen “Konzern”
ones.
Constant VW Brazil
CAE engineers
interchange with
Wolfsburg R&D
center.
VW Brazil CAE
environment is an
image from the one
in Wolfsburg.
6
Motivations
A fast and uniform defog/defrost of vehicles glazing is
very important for driving safety and occupant’s comfort.
The short timetable of the vehicles development
programs makes not feasible the work being done
exclusively on an experimental tests basis.
Thus, numerical simulation plays a very important role
through an extensive number of virtual testing and a
better understanding of the flow.
7
Goals
Development defrost/defogging air ducts in order to
achieve a uniform flow field in windshield and side
windows with high velocities.
This way defrost/defogging process will be optimized
and the standards for certifications will be reached.
8
Problem Description
Typical C and A viewed
from interior of vehicle.
Picture from SAE J902
The defrost/defogging tests are normalized in United
States by FMVSS 103 (SAE J902) and in Europe by
17/317EEC.
The “C” area in windshield (front of driver’s view) shall
be at least 80% free from ice in 20 minutes. “A” area shall
be 95% free in 40 minutes.
9
Software Tools
ANSA 12.1.5 Geometry preparation and surface mesh
Tgrid 4. Volume mesh
Fluent 6.3 Solver and post-processor
Ensight 8. Post-processor
10
Numerical Model
Numerical domain and mesh
11
Numerical Model
Numerical domain and mesh
Inlet outlet
12
Numerical Model
Hypothesis for the flow
• Steady-state
• Incompressible
• Isothermal
• Turbulent
Boundary conditions
• Inlet: constant velocity-inlet
• Outlet: constant pressure-outlet
• Other walls: non-slipping walls
13
Simulation Results
First proposal Optimized proposal
Windshield velocity vectors colored by velocity
14
Simulation Results
First proposal Optimized proposal
Side windows velocity vectors colored by velocity
left
right
15
Air Channel Geometries
First proposal
Optimized proposal
16
Air Channel Geometries
AA
BB
A
A
B
B
Optimized on top first proposal
17
Experimental Results
Defrost test: 20 minutes
VW Fox VW New Fox
18
Experimental Results
Defrost test: 20 minutes
VW Fox VW New Fox
left
right
19
Final Remarks
VW New Fox defrost/defogging air ducts were
developed on a virtual tests basis.
This way a great number of virtual analysis was
performed and air channel modifications results were
faster evaluated than only with experimental tests.
A significant improvement was achieved when
comparing with the previous VW Fox.