Aircraft Engine Technology

1
International Civil Aviation OrganizationColloqui
um on Environmental Aspects of AviationAircraf
t Emissions - The Way ForwardWillard Dodds,
ChairmanICCAIA Noise and Emissions Committee
Montreal, 9-11 April 2001
2
Elements of ICAO CAEP Approach

• Terms of Reference
• Technical Feasibility - Safety
• Environmental Benefit
• Economic Reasonableness
• Environmental Balance/Tradeoffs
• Noise
• Climate Change
• Local Air Quality
• Program Balance
• Source Reductions (Technology)
• Operational Measures (Airlines and ATC)
• Market Based Measures

Unique ICAO Resources Address Complex Issues
3
Emission Issues

• Issue Key Species Mitigation
• Climate Change - Carbon Dioxide (CO2) - Fuel
  Efficiency - Water Vapor -
  Operational Measures - NOx -
  Combustor Design
• Local Air Quality - NOx - Combustor
  Design - Carbon Monoxide (CO) - Operational
  - Unburned Hydrocarbon (HC) Measures -
  Smoke/Soot

4
Local Air Quality

• Continuous emissions reductions
• ICAO Data Bank provides current emissions
  certification data
• Required design/test margins ensure that
  certificated product emissions are below ICAO
  limits

Ref The Boeing Company
5
Climate Change

• Continuous fuel efficiency improvements driven by
  market forces
• Market based measures are being considered by
  ICAO
• Long term - open emissions trading
• Near term - voluntary programs

70 Fuel Efficiency Improvement over 40 Years
6
CO2/NOx Trade

• Higher engine pressure ratio and bypass ratio
  reduce CO2/improve fuel efficiency (SFC) and
  facilitate noise reduction

SFC
SFC (lb/lb-hr, or EI NOx)
0
10
20
30
40
50
60
Overall Pressure Ratio
7
CO2/NOx Trade

• Higher engine pressure ratio and bypass ratio
  reduce CO2/improve fuel efficiency (SFC) and
  facilitate noise reduction
• Higher pressure ratio requires higher flame
  temperature, increasing NOx formation rate

NO
SFC
X
SFC (lb/lb-hr, or EI NOx)
0
10
20
30
40
50
60
Overall Pressure Ratio
8
CO2/NOx Trade

• Higher engine pressure ratio and bypass ratio
  reduce CO2/improve fuel efficiency (SFC) and
  facilitate noise reduction
• Higher pressure ratio requires higher flame
  temperature, increasing NOx formation rate
• Better NOx technology needed to avoid increased
  emissions

NO
SFC
X
SFC (lb/lb-hr, or EI NOx)
0
10
20
30
40
50
60
Overall Pressure Ratio
9
Emissions Technology Outlook

• Continuous technology improvement has
  substantially reduced all emissions from modern
  engines
• Government and industry emissions reduction
  technology programs are underway
• Barriers to wider introduction of these
  technologies
• high development and certification investment
  with low production volume
• durability, operability, reliability production
  cost risks
• environmental tradeoffs
• unclear policy objectives
• unrealistic short term technology expectations
• ICAO WG 3 Long Term Goals Group is addressing
  technology transition issues

10
Emissions Technology Expectations

• 17 ICCAIA - Working Group 3 Papers prepared for
  CAEP/5
• Papers support IPCC Special Report projection of
  20 improvement in fuel efficiency between 1997
  and 2015
• NOx reduction technology is progressing faster
  than the IPCC scenario for NOx emissions 30-50
  below CAEP/2 limits by 2020
• Concerns relative to the rate of future progress
  due to
• uncertain research funding
• environmental and technological
  tradeoffs/priorities
• increasing challenge to improve on current
  technology

11
Summary and Conclusions

• ICAO is uniquely qualified to set aviation
  environmental standards
• Brings together resources to balance complex
  trade-offs
• Avoids proliferation of confusing, inconsistent
  and counterproductive local rules
• Globally harmonized approach for a global
  industry
• Manufacturers continually work to improve
  emissions technologies
• Need consistent and consolidated scientific basis
  for valid trade-off analyses
• Aircraft emissions reduction efforts should be
  part of a balanced program including improved
  operational factors
• Successful long term research requires continuous
  support and consistent goals
• CAEP/6 Work Program has proper elements to move
  forward on local air quality and climate