Combustor Fundamentals and Key Issues in Future Combustion ... · Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2
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Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop
CO2
72%
H2O
27.6%
SOx
~ 0.02%
NOx
84%
CO 11.8%
UHC
4% Soot 0.1%
Fuel C12.5H24 +S
Air
N2 + O2
Engine mass flow
percentage
(Jet A-1)
Aero-engine Emissions
N2
75.2%
O2 16.3%
Combustion
products
8.5%
Pollutants
0.4 %
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop
Emissions:
NOx Smoke / PMs CO UHC
Temperature Profile
Weak Extinction Stability
Pressure Loss
Efficiency
Weight Length Cost
Cold Start Comb. Instabilities
Altitude Relight
Cooling /
Durability
Aero-Engine Combustor Requirements
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop Low Emission Combustion Technologies –
Operating range for low emissions
NOx reduction principles:
reduce residence time within stoichiometric
condition
initiate combustion under lean conditions
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop
Conventional Combustion Chamber optimised for low NOx and smoke
Primary
Zone
Dilution
Zone
Air
Fuel
R Q L
Secondary
Zone
Typical Cycle
Data at T/O:
P30 ~ 30 bar
T30 ~ 850 K
AFR ~ 40
Combustor – Stoichiometry Control
RQL – Rich burn – Quick quench – Lean burn
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop
Primary
Zone
Secondary
Zone
Quenching
Dilution
Zone
Combustor
Exit
NOx – Smoke trade-off
Combustor – Stoichiometry Control
RQL – Rich burn – Quick quench – Lean burn
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop Rich Burn Combustion – RQL – Improvements
Fuel Spray Nozzle (FSN) Development
Improvement of primary atomisation of current film layer design for low smoke production without compromising current levels of weak extinction margin and operability
Optimisation of FSN aerodynamics to improve droplet transport and mixing
Low Smoke Primary Zone
Optimisation of primary zone flows to control stoichiometry
Mixing Zone
Optimisation of combustor jet mixing zone for low residence time within stoichiometric operation
Low power operation and smoke consumption not to be compromised
Combustor Cooling – Liner Architecture
High efficient cooling schemes to free combustor air for quenching
Double wall / tiled combustor architectures
New manufacturing technologies (e.g. additive laser manufacturing) enabling complex cooling arrangements at acceptable cost levels
Introduction of ceramic structures for ultimate cooling flow reduction
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop Technology Readiness Staircase – Rich Burn Improvement
LU, UK
Full-annular
Outer Aero
RR Rich Burn Improvement Programme – supported by German LuFo IV and V Programme
German Government
• Luftfahrtforschungs-programme Lufo IV, V FetMaTec, EmKoTec, EmKoVal
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop Low Emission Combustion Technologies –
Operating range for low emissions
NOx reduction principles:
reduce residence time within stoichiometric
condition
initiate combustion under lean conditions
NOx reduction principles:
reduce residence time within stoichiometric
condition
initiate combustion under lean conditions
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop
NOx Cooling
1400
1600
1800
2000
2200
2400
2600
2800
0 10 20 30 40 50 60
Air-to-Fuel-Ratio at T/O
T40
Moderate Cycle
Requirements
Nozzle Primary Zone Secondary Zone Dilution Conventional RQL Combustion
Advanced Cycle
Requirements
Nozzle Lean Burn Combustion
Lean Burn Requirement
Cycle
Principles of Lean Burn Combustion
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop
Take-off Idle Weak Extinction
Combustor 35 - 40 70 - 90 200 - 300
Turn-Down-Ratio 1 : 2 - 3 <6
Fuel Injector, conventional
~4 ~10 ~25
Fuel Injector, premixing
~25
Weak Extinction of the lean injector
50 150-200
Air – Fuel – Ratios within Combustor – Comparison
Lean Burn Combustion – Fuel Staging
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop
Fuel & Controls System
pilot/main staging
circumferential main staging may be needed
Stability control
Lean burn injector
dominates combustion performance
partially premixing, up to 70% air flow through fuel injector
internally staged with nested pilot injector
separated pilot and main stage combustion
Combustor
cooling optimised to enable lean operation and life targets
no mixing ports
Pilot flame
Main flame
Lean Burn Combustion –
RR Lean Burn Technology (ANTLE, E3E)
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop
Premixing with up to 70% of combustor air mass flow within lean burn injector
RR – Lean Burn Combustion Technology
AirCool
R Q L
Main flame
Pilot flame 10% +20% AirStoich
AirCool
Conventional (RQL) vs Lean Burn Combustor
+30%
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop
0%
10%
20%
30%
40%
50%
60%
70%
Rich Burn Lean Burn
% C
AE
P
NOx Distribution within LTO Cycle
7%
30%
85%
100%
Lean Burn Combustion – Impact of pilot stage on total emissions
For low emission lean burn systems the rich pilot zone cause significant amounts of
NOx at low power operating conditions
Further NOx reduction of lean burn systems need to include
NOx reduction measures of piloting devices
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop
BOSS/ HBK1 HPSS/ HBK3
New Big Optical Single Sector High Pressure Single Sector
Emissions up to 40 bars Emissions up to 20 bars
Non-intrusive measurements, e.g.
PDA droplet characterisation
Chemiluminescence volumetric OH*-concentration
LIF OH- / fuel concentration
Mie-scattering fuel droplet
PIV 2D velocity field
Method Variables
‚Working horse‘ for lean burn injector development
concentration
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop Lean Burn Injector – Staged Operation at Elevated Pressures
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop Principle Design Trades of Lean Burn Technology
Pilot / Main Interaction
separated combustion zones to control NOx and smoke emissions at mid and high power
interacting/communicating combustion zones at low and mid power to control efficiency and CO/UHC emissions
Burner to burner / burner to liner interaction ignition capability, altitude relight on pilot only mode pilot zone (reaction) volume for efficiency and pull-away light-around and efficiency
Operability
weak extinction stability and efficiency through entire operating range and fuel staging scenarios (entire flight mission)
steady state and transient with sufficient margin to cope for inclement weather conditions
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop Principle Design Trades of Lean Burn Technology
Combustion Efficiency
especially cruise efficiency and mission fuel burn optimisation of fuel staging strategy strongly influenced by scaling and engine cycle conditions optimisation of combustor geometry and cooling
Thermoacoustics
susceptibility of fuel preparation/injection to unsteady heat release
trade with emission performance optimising fuel staging strategy strongly influenced by scaling and engine cycle conditions
Thermal Management
degradation of stagnant fuel at part power conditions for fuel circuits being not operative
heat shielding and active cooling of stagnant fuel especially in the vicinity of discharge orifice
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop Principle Design Trades of Lean Burn Technology
System Integration
Combustor mechanical integrity – wall cooling to achieve combustor life
Fuel and controls system for fuel staged system; fail safe scenarios
Cost, Weight, Complexity of combustor module and fuel system
.....
Lean Burn is a revolutionary step in combustion technology
development (no evolution from advanced state-of-the-art technology)
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop Combustor Technology Implementation Strategy
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop Key Enablers
for Rich and Lean Combustion Fuel Spray Nozzles
- Atomisation and fuel placement
- Low smoke production
- Thermal management
Combustion / Mixing
- Premixing
- Smoke consumption and NOx control
- Combustor turbine interaction CTI
- Combustion Modelling - Two Phase Flows; Primary/Secondary fuel break -up - Chemistry, Turbulence - Emissions Focus Soot and CO/UHC
Liner Architecture / Durability
- High efficient wall cooling
- Alternative designs, material and manufacturing (e.g. DLD, CMC)
- Costs
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin – FORUM-AE -non CO2 Mitigation Technology Workshop
Questions ?
Rolls-Royce proprietary data
Combustor Fundamentals and Key Issues in Future Combustor Technology March 2017 – Berlin FORUM-AE - non CO2 Mitigation Technology Workshop