1. NOISE REDUCTION FOR INTERNAL COMBUSTION ENGINE
Chris Morehouse: Team Leader
Julie Maier: Resonator Lead
Ted Zachwieja:
ANC Lead
Caroline Bills:
Lead Engineer
Prof. Edward Hanzlik:
Team Guide
Dr. Alan Nye: Customer
Mr. Jagdish Tandon:
Graduate TA
P11221
NOISE REDUCTION FOR INTERNAL COMBUSTION ENGINE

2. Project Overview Understand phenomenon of sound
Design sound attenuation system(s)
Maintain engine performance

3. CUSTOMER NEEDS

4. ENGINEERING SPECIFICATIONS

5. Design Options HELMHOLTZ RESONATOR CONCENTRIC TUBE RESONATOR
ABSORPTION MUFFLER
ACTIVE NOISE CANCELLATION

6. RESONATOR DEMONSTRATION MODULE
Study of resonators
Variable cavity lengths (both)
2 outer pipe options (Concentric Tube only)
CONCENTRIC TUBE RESONATOR
HELMHOLTZ RESONATOR

7. RESONATOR TESTING Concentric Tube: Helmholtz: Vary Frequency
Vary Length
Waveform
Helmholtz:
Vary frequency
Waveform
CONCENTRIC TUBE
RESONATOR
TONE GENERATOR
(LAPTOP)
SOUND LEVEL
METER
SPEAKERS

8. CONCENTRIC TUBE FIXED FREQUENCY TEST RESULTS
Predicted:
Max at ½ λ
~ 20 to 30 dBA
Result:
Max 6 dB
Offset
Reduction at ½ λ > ¼ λ
SCT similar results
SCT less reduction than LCT for most

9. CONCENTRIC TUBE FIXED LENGTH TEST RESULTS
Predicted:
Max at ½ λ
Less at ½ λ multiples
~ 20 to 30 dBA
Result:
Offset from λ multiples
Max ~ 10 dBA (550 Hz)
SCT similar results
SCT less reduction
Possible sources of error:
Exact location cavity length (o-ring or plunger end)
Possible weird wave motion in plunger rod section

10. HELMHOLTZ RESONATOR FIXED FREQUENCY TEST RESULTS
Prediction:
Modest reduction (at least 10 dBA)
Narrow Frequency Range
Result:
Reduction offset
Achieved expected level

11. WAVEFORM TESTING RESULTS
target peak frequencies for each resonator
C-Tube – around ½ λ for each F
Helm – freq equation

12. CONCENTRIC TUBE RESONATOR RESULTS
Optimal = 26 cm
Overall ~ 9.6 dBA
Optimal based on reduction at peaks and overall reduction
Modest attenuation across broad frequency range

13. HELMHOLTZ RESONATOR RESULTS
No clear optimal
Overall reduction ~ 0 dBA
Behavior of resonator – narrow frequency band
Possibly array

14. Absorption Muffler: overview
Outer steel casing
Perforated inner steel pipe
5 shapes
Steel end caps
Packing material in cavity
3 materials
3 densities

15. Absorption Muffler: material & density options
Fiberglass
Mineral Wool
Steel Wool
Fiberglass & Mineral Wool:
175, 200, and 225 g/L
Steel Wool:
Grades 0000, 1, and 4
Mineral Wool – made from molten glass, stone, or slag which is spun into a fiber-like structure similar to common household insulation
Steel Wool grade - determines the thickness of the strands in the steel wool

16. Absorption Muffler Testing
Test 1: Optimal Packing Material & Density
Standard Shape Option only
Test 2: Optimal Shape
Optimal Material & Density only

17. Optimal material Results

18. Optimal shape Results

19. Active Noise Cancellation
Additive property of sound
Noise cancellation

20. Dipole Box

21. Feed forward Control

22. Project Evaluation Resonator Demo Absorption ImagineRIT
Resonator behaved as expected
Waveforms testing success
Absorption
Steel wool better material
Geometry needs further testing
ImagineRIT
Successful
Lots of positive feedback
Back pressure testing
Inconclusive
Overall = success
Very good knowledge gain
Good start for follow-on projects
SAE Recommendations
Steel Wool packed muffler
Concentric Tube Resonator

23. RECOMMENDATIONS Resonators Absorption ANC
Variable length for testing on ICE
Array of Helmholtz resonators
Optimize concentric tube for Formula SAE
Nature of Offset
Absorption
Composite Material layering
Continue Steel Wool Density Testing
ANC
Complete working system (demo)
Apply to B&S Engine
Develop Feedback system
Develop prediction models for all
Design Back Pressure testing system
Engine Mounted w/ Engine Loaded

24. Questions?? References:
Bell, Lewis H. Industrial noise control: Fundamentals and Applications. New York : M. Dekker, Print.
ANC patent on EDGE website