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P11221. 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.
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P11221 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
Understand phenomenon of sound Design sound attenuation system(s) Maintain engine performance Project Overview
ABSORPTION MUFFLER Design Options • HELMHOLTZ RESONATOR • CONCENTRIC TUBE RESONATOR • ACTIVE NOISE CANCELLATION
RESONATOR DEMONSTRATION MODULE • Study of resonators • Variable cavity lengths (both) • 2 outer pipe options (Concentric Tube only) • CONCENTRIC TUBE RESONATOR • HELMHOLTZ RESONATOR
Concentric Tube: Vary Frequency Vary Length Waveform Helmholtz: Vary frequency Waveform CONCENTRIC TUBE RESONATOR TONE GENERATOR (LAPTOP) SPEAKERS SOUND LEVEL METER RESONATOR TESTING
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 FREQUENCY TEST RESULTS
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
HELMHOLTZ RESONATOR FIXED FREQUENCY TEST RESULTS • Prediction: • Modest reduction (at least 10 dBA) • Narrow Frequency Range • Result: • Reduction offset • Achieved expected level
CONCENTRIC TUBE RESONATOR RESULTS • Optimal = 26 cm • Overall ~ 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 shapes • Steel end caps • Packing material in cavity • 3 materials • 3 densities
Absorption Muffler:material & density options • Fiberglass & Mineral Wool: • 175, 200, and 225 g/L • Steel Wool: • Grades 0000, 1, and 4 • Fiberglass • Mineral Wool • Steel Wool
Absorption Muffler Testing • Test 1: Optimal Packing Material & Density • Standard Shape Option only • Test 2: Optimal Shape • Optimal Material & Density only
Active Noise Cancellation Additive property of sound Noise cancellation
Project Evaluation • Overall = success • Very good knowledge gain • Good start for follow-on projects • SAE Recommendations • Steel Wool packed muffler • Concentric Tube Resonator • Resonator Demo • 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
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 all • Design Back Pressure testing system • Engine Mounted w/ Engine Loaded
Questions?? • 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