Acoustic Development: Motorbike Muffler
31.09.02ZS Motorrad-TeamDetlev Rammoser+49 (0)821 4103 594
Conflict: Acoustic - Power - Design
Initial Problem:
- Pass by level: Tailpipe noise too loud
- Subjective noise: Sound too aggressive
- Pressure loss: Limit already reached
- Design: Volume is fixed
Acoustic Development: Motorbike Muffler
31.09.02ZS Motorrad-TeamDetlev Rammoser+49 (0)821 4103 594
- Better damping of the specific frequencies
- Rapid evaluation of different principles with GT-Power(interference, volume distribution, resonators)
- Experimental validation
How this can be solved ?
31.09.02ZS Motorrad-TeamDetlev Rammoser+49 (0)821 4103 594
Basic system - resonances
U/min U/min
Acoustic Development: Motorbike Muffler
31.09.02ZS Motorrad-TeamDetlev Rammoser+49 (0)821 4103 594
Quick mesh generation with the muffler preprocessor (~1h)
Acoustic Development: Motorbike Muffler
31.09.02ZS Motorrad-TeamDetlev Rammoser+49 (0)821 4103 594
Basic muffler: principle layout
Acoustic Development: Motorbike Muffler
Transmissionloss 20 °C
-20
-10
0
10
20
30
40
50
60
0 100 200 300 400 500 600 700 800
Frequency [Hz]
TL
[d
B]
GTP Basis 20 °C
Exp. Basis 20 °C
31.09.02ZS Motorrad-TeamDetlev Rammoser+49 (0)821 4103 594
Model validation (basic muffler)
Acoustic Development: Motorbike Muffler
Transmissionloss 650 °C
-20
-10
0
10
20
30
40
50
60
0 100 200 300 400 500 600 700 800
Frequency [Hz]
TL
[d
B]
GTP Basis 20 °C
GTP Basis 650 °C
frequency shift f0
31.09.02ZS Motorrad-TeamDetlev Rammoser+49 (0)821 4103 594
Temperature influence: frequency shift
Acoustic Development: Motorbike Muffler
31.09.02ZS Motorrad-TeamDetlev Rammoser+49 (0)821 4103 594
Modified muffler
Acoustic Development: Motorbike Muffler
31.09.02ZS Motorrad-TeamDetlev Rammoser+49 (0)821 4103 594
Transmission loss of muffler variants
Basis with longer resonators
modified
Basis
Acoustic Development: Motorbike Muffler
31.09.02ZS Motorrad-TeamDetlev Rammoser+49 (0)821 4103 594
Modified system - highly reducedresonances
Acoustic Development: Motorbike Muffler
U/min U/min
Overall level [dB(A)]400 Hz
6th Order
600 Hz
8th Order
120 Hz
2nd Order 600 Hz
6th Order
31.09.02ZS Motorrad-TeamDetlev Rammoser+49 (0)821 4103 594
Basic system - order analysis
Acoustic Development: Motorbike Muffler
31.09.02ZS Motorrad-TeamDetlev Rammoser+49 (0)821 4103 594
Improvement of - 3 dB wrt. nearfield
- 3 dB
Overall level [dB(A)]
Acoustic Development: Motorbike Muffler
- 20 mbar
Basis with longer resonators
modifiedBasis
31.09.02ZS Motorrad-TeamDetlev Rammoser+49 (0)821 4103 594
Pressure loss analysis
Acoustic Development: Motorbike Muffler
31.09.02ZS Motorrad-TeamDetlev Rammoser+49 (0)821 4103 594
Conclusion
The technical solution:
- Elimination of the relevant frequencies by interference effects
- Quick evaluation of the variants with simple GT-Power models
- After 1st hardware loop promising results
Acoustic Development: Motorbike Muffler