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A. Dolinar
AVL List GmbH (Headquarters)
Confidential
EXHAUST SOUND DESIGN
for a downsized High Performance Vehicle
A. Dolinar, B. Graf, S. Brandl | | 04 Oktober 2017 | 2Confidential
• Introduction
• Exhaust System NVH Development
• Exhaust System Orifice Noise Approaches
• Exhaust System Orifice Noise Simulations and Measurements
• Exhaust Sound Design Application
• Excitation measurements
• GT-POWER simulations
• Active noise attenuation
• Summary
CONTENT
A. Dolinar, B. Graf, S. Brandl | | 04 Oktober 2017 | 3Confidential
INTRODUCTION
Cyl 2
Cyl 3
Cyl 1
Cyl 4
Intake system Exhaust system
Tailpipe Noise:
Pulse noise +
Flow generated
noise
Tailpipe Noise:
Pulse noise +
Flow
generated
noise
Shell Noise
Combustion and
Mechanical Noise
Sources of exhaust noise
Pulses (opening/closing of exhaust valves) exhaust orifice order noise
Exhaust gas flow noise exhaust orifice flow noise
Shell noise
TC noise
Vibration transfer to vehicle
EXHAUST SYSTEM NOISE/SOUND
A. Dolinar, B. Graf, S. Brandl | | 04 Oktober 2017 | 4Confidential
EXHAUST SYSTEM NVH DEVELOPMENT
Simulation
Transfer function
Orifice noise
Hardware
Prototyping
Transfer function measurement
Orifice noise measurement
NVH CONTRIBUTION
A. Dolinar, B. Graf, S. Brandl | | 04 Oktober 2017 | 5Confidential
EXHAUST SYSTEM NVH DEVELOPMENT
NVH Facilities
Powertrain NVH Test Beds
Driveline NVH Test Beds
4WD Acoustic Chassis Dyno
Test Track (incl. pass-by capability)
NVH CONTRIBUTION
A. Dolinar, B. Graf, S. Brandl | | 04 Oktober 2017 | 6Confidential
GENERAL EXHAUST SYSTEM NVH APPROACHES
ORIFICE NOISE
DEVELOPMENT:
OVERVIEW OF
2 MAIN APPROACHES
Orifice NoiseExcitation Transfer Behaviour
Refinement
Frontloading
Layout
Procurement
In-Vehicle
Assessment
Fine-Tuning Loop
(orifice measurements)
Fine-Tuning Loop
(transfer function)
A. Dolinar, B. Graf, S. Brandl | | 04 Oktober 2017 | 7Confidential
EXHAUST SYSTEM NVH DEVELOPMENT
ORIFICE NOISE DEVELOPMENT: MUFFLER SIMULATION
COMPONENT MODEL:
Exhaust component(s) - calculation of:
transmission loss
transfer function
insertion loss
A. Dolinar, B. Graf, S. Brandl | | 04 Oktober 2017 | 8Confidential
EXHAUST SYSTEM NVH DEVELOPMENT
ORIFICE NOISE DEVELOPMENT: TL & TF MEASUREMENT/DEVELOPMENT
LOUDSPEAKEREXCITATION
UPSTREAM MICROPHONES
DOWNSTREAM MICROPHONES
Acoustic flow rig at
KTH Stockholm
Zero flow test rig
A. Dolinar, B. Graf, S. Brandl | | 04 Oktober 2017 | 9Confidential
Simulation
EXHAUST SYSTEM NVH DEVELOPMENT
ORIFICE NOISE DEVELOPMENT: HYBRID SIMULATION AND MEASUREMENT
Result
Measurement
Mikrophone
exhaust pulses
0.80
0.90
1.00
1.10
1.20
1.30
1.40
1.50
1.60
1.70
-110 -38 34 106 178 250 322 394 466 538 610
°CA
bar
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
6000
Exhaust Orifice Noise
40
50
60
70
80
90
1000 2000 3000 4000 5000engine speed (rpm)
SP
L d
B(A
)
2nd order measurement4th order measurement2nd order simulation4th order simulation
The pressure pulses
(static and dynamic
pressure) are measured
together with the exhaust
gas temperature.
These are then used for
the GT-POWER
excitation boundary
condition
pressure traces for
different engine conditions
GT-POWER
exhaust system model
Exhaust orifice noise results,
measured & GT-POWER
A. Dolinar, B. Graf, S. Brandl | | 04 Oktober 2017 | 10Confidential
APPLICATION: EXHAUST SOUND DESIGN3 CYLINDER HIGH PERFORMANCE ENGINE
ORIFICE NOISE APPROACH
Development of a dominant/sporty exhaust orifice noise
Boundary conditions
Pass-by noise limit
Exhaust system back pressure
Active orifice noise attenuation
Approach
Excitation from engine dyno measurement
Transfer function development in GT-POWER
Orifice noise from measured excitation & GT-POWER transfer function development
Additionally active noise attenuation
A. Dolinar, B. Graf, S. Brandl | | 04 Oktober 2017 | 11Confidential
APPLICATION : EXHAUST SOUND DESIGN3 CYLINDER HIGH PERFORMANCE ENGINE
EXHAUST SYSTEM MODELLED WITH GEM3D AND GT-ISE V2017
A. Dolinar, B. Graf, S. Brandl | | 04 Oktober 2017 | 12Confidential
ORIFICE ORDER NOISE SIMULATION & ACTIVE ATTENUATION
APPLICATION : EXHAUST SOUND DESIGN3 CYLINDER HIGH PERFORMANCE ENGINE
Passive exhaust system&
Active exhaust system
range around 400Hz increased3rd order increase
4.5th order increase
Passive exhaust system
A. Dolinar, B. Graf, S. Brandl | | 04 Oktober 2017 | 13Confidential
GT-POWER is successfully used within AVL’s intake and exhaust system acoustic development processes.
GEM 3D is used both for the intake and exhaust line for the modelling of air filter boxes, resonators high frequency dampers and exhaust mufflers.
GT-POWER is used for acoustic transfer function and orifice noise development. Acoustic excitations are coming either from thermodynamic simulations or from measurements. Both give good insight to the acoustic behaviour of intake and exhaust systems in terms of acoustic damping and orifice noise.
SUMMARY
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