vwag - simulation of exhaust system noise

8/13/2019 VWAG - Simulation of Exhaust System Noise

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Konzernforschung

Simulation of Exhaust System Noiseusing 1D-CFD / 3D-BEM Methods

for the VW EcoRacer Concept Car

L. Miranda, Dr.Henry-Paul Bensler

LMS Conference Europe Stuttgart, 17.-18.April, 2007


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VW EcoRacer 2005

Motivation: Sound Tuning of Eco-Racer


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Driving performance0-100 at 6.3s

vmax230 km/h

Driving

pleasurewithout regret

VariabilityLightweight design and

low consumptionRoofwings for a better boarding

removable roof

removable rear roofpart

removable windscreen

850 kg

3.4 l/100km

Diesel, DSG

CFK, Al

EcoRacer Attributes


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cW-optimised for 3L Stripping as an additional

feature!

Optical driving pleasure

FascinationFascination

LowLowconsumptionconsumption

AffordableAffordablelightweightlightweightdesigndesign

DrivingDrivingpleasurepleasurewithwithDiesel-PowerDiesel-Power

Extreme Sportiness

Driving behaviour

likeLotus Elise

Cost potential of

production concepts

for low volumes

Economy at sporty

driving performance

< 4 L/100km at


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Completely closed

Roof parts removed

Rear roof part removed

Windscreen removed

Variability of the bodyshell


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_ Improvement of the sound emision in low frequency [250 300 Hz] range

_ Reduction of flow noise

_ Calculation of the transmission loss

_ Engine noise simulation 3 Cylinder TDI 85 KW with

Gas dynamics simulation:

_ Simulation TDI Engine on test chamber (Performance)

_ Simulation TDI Engine + Exhaust system (Sound Tuning)

_ Audible sound files generation with WNoise for subjective evaluation

_ Optimisation of exhaust pipe location

Exhaust System Noise Goals


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Input Models

CAD Model

Virtual Lab BEM Model

WAVE Modell

Ansaugung

Luftfilter

ESD (4 Lang)

KAT

LLK

Turbine

Verdichter

Motor

Methodology


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Airfilter

Muffler

Catalisator

LLK

Turbine Verdichter

Engine

intake

Engine Model 1D-CFD


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0

50

100

150

200

250

300

350

1000 1500 2000 2500 3000 3500 4000 4500

Drehzahl [1/min]

Drehmom

ent[Nm]

Messung M7

Simulation M7

0

10

20

30

4050

60

70

80

90

100

1000 1500 2000 2500 3000 3500 4000 4500

Drehzahl [1/min]

Leistung[KW]

Messung M7

Simulation M7

0

50

100

150

200

250

300

350

400

450

1000 1500 2000 2500 3000 3500 4000 4500

Drehzahl [1/min]

Luftdu

rchsatz[Kg/h]

Messung M7

Simulation M7

0

20

40

60

80

100

120

140

160

180

200

1000 1500 2000 2500 3000 3500 4000 4500

Drehzahl [1/min]

Pmax

Zyl.1[bar]

Messung M7

Simulation M7

1-D CFD Performance


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6 2

0

4

3

1

5Fiberglass /Advantex

Perforation

serie

Muffler Designs


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standard with flow noiseInitial Case 0:

Areas of low Sound Intensity

Engine Orders: 1.5 3.0 4.5 6.0 7.5


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Best in class 3 und 4

T=900 K

Simulation of Transmission Loss Analysis for Muffler onlyPrototypes


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150 mm 150 mm50 mm

75 mm 75 mm

75 mm 75 mm

55 mm55 mm

100 mm

350 mm

100 mm

350 mm

55 mm 55 mm

20 mm

20 mm

20 mm

41 mm

3

4

Variante

41mm

20 mm

20 mm

41 mm

41 mm

45 %

20%20 %

20 %45 %

3.5 mm

Lchern

41 mm

41 mm

3 Chamber Muffler

Mufflers Models for 3-D BEM Analysis:


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3-D BEM Simulation: Sound Energy of MufflerOptimisation ofInner Muffler Design (init ial 3 Chamber Prototype shown)

220 Hz 315 HzModal Response of Excitation

455 Hz 545 Hz


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Komponente wirksame Lnge Gastemperatur

n = 1 n = 2 n = 3 n = 4

[mm] [K] [Hz] [Hz] [Hz] [Hz]

v. Turbine Strecke Zyl.1 432 900 335 1005 1676 2346

Gesamtstrecke Zyl. 1 Lang 2450 770 56 169 282 395

Gesamtstrecke Zyl. 1 Kurz 2229.4 770 62 186 310 433

Gesamtstrecke Zyl. 1 Center 1985 770 69 208 347 486

vor Kat 568 780 461 923 1384 1846

KAT - ESD 255.3 770 935 1870 2806 3741

Endrohr Lang 655 720 390 780 1170 1559

Endrohr Kurz 434.4 720 573 1146 1719 2292

Endrohr Center 190 720 1196 2392 3588 4784

Resonanzfrequenzen

1-D CFD Resonance Frequencies in different Exhaust SystemLocations for different Exhaust Pipe Lengths:


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Left Right

30

40

50

60

70

80

90

100

1000 1500 2000 2500 3000 3500 4000 4500

Drehzahl [U/min]

SPL

dB(

A)

Overall

1.5 MO

3.0 MO

4.5 MO

6.0 MO

7.5 MO30

40

50

60

70

80

90

100

1000 1500 2000 2500 3000 3500 4000 4500

Drehzahl [U/min]

SPL

dB

(A)

Overall

1.5 MO

3.0 MO

4.5 MO

6.0 MO

7.5 MO

1-D CFD Sound Pressure Level of Prototype 4 with long DualExhaust Pipes (left and right ):


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Production Muffler

Prototype 4

1-D CFD Results: Prototype 4

Engine Orders: 1.5 3.0 4.5 6.0 7.5


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_ Good correlation between simulation and test

of engine performance required

_ Significant improvement of exhaust system

sound was achieved

_ Combined usage of 1D-CFD and 3-D BEM

methods very effective for exhaust system

engineering

_ Very good method to quantify and evaluate

exhaust system sound

Conclusions


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Methodology: Transmission Loss Analysis of Muffler only

vwag - simulation of exhaust system noise

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