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.