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??