Noise Control for Internal
Combustion Engine Exhaust
Brad Fiedler
Chris VanWagenen
Greg Wodzicki
Kyle Desrosiers
Design Review – Week 5
Agenda







Introduction / Background
Understanding the Problem and Current Technology
Courses of Action
Course of Action Comparison
Best Courses of Action
Closing
Questions
Introduction/Background
Background
Customer Needs
Design Objectives
Risk Assessment
Gantt Chart
FSAE Formula One Vehicle
What year Vehicle is this?
Problem Background



FSAE rules dictate engine noise under 110dB.
Current Passive Noise Control device (Glass pack) holds
engine sound from wide range above and below 110dB
Current technology is not tuned for optimal noise
reduction or engine performance
Introduction / Background
Design Objectives
Utilize Active / Passive Noise Cancellation Technology to:
 Maintain engine output under FSAE limit of 110dB.
 Adhere to all FSAE Rules
 To not add significant weight to vehicle
 Maintain/Improve engine performance
 Lower Vehicle Center of Gravity
Introduction / Background
Performance Objective
Possible Performance Effects of Different Exhaust Technology:
 A – No Exhaust Tuning
 B – Traditional Exhaust Length Tuning
 C – Possible Active Noise Cancellation Improvement*
* Dependent on cancellation method
Introduction / Background
Risk Assesment
xxxxxxxxxx:
 xxxxxx
Introduction / Background
Project Plan
xxxxxxxxxx:
 xxxxxx
Introduction / Background
Understanding the Problem and
Current Technology
Internal Combustion Engine
ICE Exhaust Acoustics
Tuning a Exhaust
Understanding ANC
Lawnmower Engine
Glass Pack Muffler
Turbo Muffler
Baffle Muffler
Understanding the 4 Stroke ICE
Understanding the Problem and Current Technology
Understanding Optimal Acoustics
Understanding the Problem and Current Technology
Calculating Tuned Exhaust Length
𝑘 ∗ 𝐸𝑜 ∗ 𝑉𝑠
𝐿=
𝑁


Understanding the Problem and Current Technology
𝑁 = Crankshaft Speed in RPM
𝑘 = Constant
Understanding Active Noise Cancellation - 1


Superposition
Harmonics
Understanding the Problem and Current Technology
Understanding Active Noise Cancellation - 2
𝐵𝑒 𝑖𝑤𝑡−𝑖𝑘(𝐿𝑡 −𝐿1 )
𝐿1
𝐿𝑡
𝐴𝑒 𝑖𝑤𝑡−𝑖𝑘𝑥
Signal Equations:
𝐴𝑒 𝑖𝑤𝑡−𝑖𝑘𝑥 +
𝐵𝑒 𝑖𝑤𝑡−𝑖𝑘(𝐿𝑡−𝐿1)
𝐴𝑒 𝑖𝑤𝑡−𝑖𝑘𝑥 + 𝐵𝑒 𝑖𝑤𝑡−𝑖𝑘(𝐿𝑡 −𝐿1) = 0
Noise Reduction:
=0
𝑁𝑜𝑖𝑠𝑒 𝑅𝑒𝑑𝑢𝑐𝑡𝑖𝑜𝑛 =
𝐴+ 𝐵𝑒 𝑖𝑘(𝐿1) = 0 @ 𝑥 = 𝐿𝑡
Understanding the Problem and Current Technology
𝑃 𝑤𝑖𝑡ℎ 𝐶𝑎𝑛𝑐𝑒𝑙𝑙𝑖𝑛𝑔
𝑃 𝑤𝑖𝑡ℎ𝑜𝑢𝑡 𝑐𝑎𝑛𝑐𝑒𝑙𝑙𝑎𝑡𝑖𝑜𝑛
Glass Pack




Exhaust Travels through Pipe with Perforated Holes
Sound Insulation Absorbs Sound
Minimal Back Pressure
Least Effective in Reducing Sound
Understanding the Problem and Current Technology
Turbo Muffler






No Baffles
Exhaust Forced to turn
back and forth
Increases Exhaust Length
Increased Back Pressure
with each turn
Sound Insulation Absorbs
Sound
Moderately Effective in
Reducing Sound
Understanding the Problem and Current Technology
Baffle Muffler




Reflects Exhaust
Throughout Chamber
Reflections Cancel each
other
Most Back Pressure created
Greatest Sound Reduction
Understanding the Problem and Current Technology
Lawnmower Engine
xxxxxxxxxx:
 xxxxxx
Introduction / Background
Courses of Action
Noise Reduction Techniques Explored
Signal Processing for ANC
Internal ANC with Microphone and Feedback
Courses of Action
Exhaust in Speaker Chamber
Multiple Speaker with Error Microphone
Courses of Action
Signal Generation:
Digital Signal Processing
Courses of Action
Filtering Technique 1:
Filtered-X Least Mean Squared Filter
Courses of Action