The Aerodynamic Challenges of Aero-engine Gas-Turbine

47 Pages·2013·7.36 MB·English

by  Mark Brend

L T O
ECTURE ITLE AND VERVIEW
“The Aerodynamic Challenges of Aero-engine
Gas-Turbine Combustion Systems”
Prof. J. J. McGuirk
Dept. of Aero. & Auto. Eng.,
Loughborough University, UK.
1. Intro. & background
2. Expt. facilities/techniques
3. CFD tools – turbulence
4. Compressor/combustor aerodynamic coupling
5. Combustor/turbine interaction
6. Fuel injectors – aero- & hydro-dynamics, aero-acoustics
7. A brief forward look
8. Summary/Conclusions/Acknowledgements
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A -
ERO ENGINE COMBUSTION SYSTEM
RR Trent 700
Combustor

A330 engine
 1st of Trent family

EIS: 1995

57% market share

1000 units sold
(Nov. 2012)
RR website:
“lowest lifecycle fuel burn, lowest
emissions and lowest noise
levels of any A330 engine”

The combustor accounts for ~1% of engine cost & weight.
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C
OMBUSTOR DESIGN REQUIREMENTS

High combustion efficiency (>99.5%) – complete fuel burn to
liberate all chemical energy as heat (high and low power)

Good combustion stability - combustor operates over a wide
range of AFR’s

Ease of ignition - both on ground and high altitude re-light

Low total pressure loss – maximise overall efficiency

Clean exhaust – Emissions must meet future regulations
(CO, UHCs, NO , smoke)
x

Good temperature traverse quality – overall and radial - to
ensure max. performance and turbine life

Thermal and mechanical integrity – high combustor life,
influences wall cooling, thermo-acoustic properties

Low weight/cost
Aerodynamics - mixing, cooling, atomisation, acoustic processes
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R B C S
ICH URN OMBUSTOR TYLE

 Lean dilution zone, hot enough for no
Pre-diffuser -
smoke + extra air for traverse control
dump diffuser
design

RQL
idea

Rich burn primary zone. 
Rapid dilution/mixing to
stable down to low power
minimise stoichiometric zones
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E
NVIRONMENTAL IMPACT

ACARE TARGETS
Reducing environmental impact
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L - T
EAN BURN ECHNOLOGY

Large multi-stream swirlers

Staged, separate, rich pilot
(for low power, stability) and
lean main (for low No )
x
15%
40%
70%
20%
15%
40%
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L – T -
EAN BURN HERMO ACOUSTICS

Heat release from flame can couple with combustion
system acoustics

All flames (but particularly Lean Burn) are prone to this
1. Unsteady heat release causes acoustic wave propagation
2. Pressure drop across injector fluctuates
3. Fluctuations in AFR of mixture reaching flame
4. (Possible) reinforcement of unsteady heat release
Unsteady Heat
Release
Air and fuel
Pressure
mass flow
oscillations
oscillations

Aerodynamic and aero-acoustic properties of injector and
cooling flows crucial
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E - 1
XPERIMENTAL FACILITIES

Single or simplified flow elements
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E - 2
XPERIMENTAL FACILITIES

Single sector or multi-sector (airflow/liquid flow)
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E - 3
XPERIMENTAL FACILITIES

Fully annular + compressor (airflow)
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