chris morehouse: team leader julie maier: resonator lead ted zachwieja: anc lead caroline bills:...
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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
NOISE REDUCTION FOR INTERNAL
COMBUSTION ENGINE
P11221
PROJECT OVERVIEW
Understand phenomenon of sound
Design sound attenuation system(s)
Maintain engine performance
CUSTOMER NEEDS
ENGINEERING SPECIFICATIONS
DESIGN OPTIONS
ABSORPTION MUFFLER
CONCENTRIC TUBE RESONATOR
HELMHOLTZ RESONATOR
ACTIVE NOISE CANCELLATION
RESONATOR DEMONSTRATION MODULE
Study of resonators Variable cavity lengths (both) 2 outer pipe options (Concentric Tube only)
HELMHOLTZ RESONATORCONCENTRIC TUBE RESONATOR
RESONATOR TESTING
Concentric Tube: Vary Frequency Vary Length Waveform
Helmholtz: Vary frequency Waveform
CONCENTRIC TUBERESONATOR
TONE GENERATOR(LAPTOP)
SOUND LEVEL METER
SPEAKERS
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
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
Prediction: Modest reduction
(at least 10 dBA) Narrow Frequency
Range
Result: Reduction offset Achieved
expected level
HELMHOLTZ RESONATOR FIXED FREQUENCY TEST RESULTS
WAVEFORM TESTING RESULTS
CONCENTRIC TUBE RESONATOR RESULTS
Optimal = 26 cmOverall ~ 9.6 dBA
HELMHOLTZ RESONATOR RESULTS
No clear optimal Overall reduction ~ 0 dBA Behavior of resonator – narrow frequency band
Possibly array
ABSORPTION MUFFLER:OVERVIEW
Outer steel casing Perforated inner steel pipe
5 shapesSteel end capsPacking material in cavity
3 materials3 densities
Fiberglass
Mineral Wool
Steel Wool
Fiberglass & Mineral Wool:
175, 200, and 225 g/L
Steel Wool: Grades 0000, 1, and 4
ABSORPTION MUFFLER:MATERIAL & DENSITY OPTIONS
ABSORPTION MUFFLER TESTING
Test 1: Optimal Packing Material & DensityStandard Shape Option only
Test 2: Optimal ShapeOptimal Material & Density only
OPTIMAL MATERIAL RESULTS
OPTIMAL SHAPE RESULTS
ACTIVE NOISE CANCELLATION
Additive property of sound
Noise cancellation
DIPOLE BOX
FEED FORWARD CONTROL
Resonator Demo Resonator behaved as
expected Waveforms testing
successAbsorption
Steel wool better material
Geometry needs further testing
ImagineRIT Successful Lots of positive
feedbackBack pressure
testing Inconclusive
Overall = success Very good knowledge
gain Good start for follow-on
projects
SAE Recommendations Steel Wool packed
muffler Concentric Tube
Resonator
PROJECT EVALUATION
RECOMMENDATIONS
Resonators 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 allDesign Back Pressure testing systemEngine Mounted w/ Engine Loaded
References: Bell, Lewis H. Industrial noise control: Fundamentals and
Applications. New York : M. Dekker, 1982. Print. http://students.sae.org/competitions/formulaseries/rules/
2011fsaerules.pdf http://focus.ti.com.cn/cn/lit/an/spra042/spra042.pdf ANC patent on EDGE website
QUESTIONS??
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