secondary burning

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secondary burning
HIGH FUEL TO AIR PROBLEM / CHALLENGE
• To increase specific thrust, future engines will
increase overall fuel-air ratios
• JSF, other commercial products affected
Flow Direction
JSF
Compressor
Combustor
Turbine
F119
1
TURBINE COOLING TRENDS
• Thrust and performance
increases monotonically with
turbine inlet temperature, qt
• Isp and hthermal also increase
– Because of associated
increase in pc
• STRONG INCENTIVE TO
INCREASE qt
• Turbine efficiency decreases
• Blade materials: oxidationresistant, high s, such as
Nickel and Cobalt based alloys
Increase limited by
metallurgical progress
Most current advancement
due to air-cooling
• Introduction of directionallysolidified and single-crystal
blade materials
2
WHERE DOES COOLING AIR COME FROM?
Turbine blades cooled with
compressor discharge air
Other components
(burner, liners, disks, etc.)
also cooled with
compressor air
3
FILM COOLING BEHAVIOR
4
COOLING STRATEGIES: FILM COOLING
5
COOLING STRATEGIES: INTERNAL COOLING
•
•
•
•
•
Cooling air is pumped through inside of
blades
– Air is pumped in at root and makes
multiple passes before exiting at
root
Material is cooled by forced convection
on inside surface and by conduction
through blade
Different regions of blades can have
different cooling profiles
Large surface area on inside
Many designs employ roughened
internal microfin structure
6
PHENOMENOLOGICAL OVERVIEW
PW229
EMISSIONS INTO
TURBINE
EXHAUST
MIGRATION
SURFACE
HEAT FLUX IMPACT
7
F119-100 1st ROTOR
8
F119-100 1st ROTOR
9
F119-100 1st ROTOR
10
BOAS: BLADE OUTER AIR SEAL
11
BLADE OUTER AIR SEAL (BOAS) POST EVENT
12
DETAIL: BOAS
13
TURBINE ROTOR BLADE FAILURE (ROLLS-ROYCE)
14
RESEARCH QUESTIONS
• What is impact to turbine surfaces due to secondary reactions?
• What is change in surface heat flux due to a local reaction over a range of
operating conditions
– What is influence of blowing ratio, B?
– What is influence of the total fuel content, E?
– What is influence of flow and chemical time scales, Da = tflow/tchem?
– Etc…
• What if you knew answers?
– How do you use this information?
– How to incorporate into a design system framework?
15
EXPERIMENTAL INVESTIGATION
Fuel rich air flow
Air-Side Injection
Heat Flux Gauges
Nitrogen-Side Injection
16
EFFECT OF LOCAL REACTION
B = 1.0, Da = 13, CO = 65,000 ppm (Moderate Energy Content)
1.E+06
Air Side
Nitrogen Side
Correlation
Predicted Cooling
Heat Flux, W/m
2
1.E+06
Downstream
8.E+05
25%
Upstream
6.E+05
Coolant Injection at x/D = 0
4.E+05
-20
-10
0
10
Position, x/D
20
30
40
25% augmentation over inert side
Cooled side injection agrees to within 10% of literature values and correlation
17
CFD STUDY: B = 0.5 (ATTACHED JET)
TOTAL TEMPERATURE CONTOURS — Tflame = 1840 K
2780
1800
2492
1640
2204
1480
1916
1320
1628
1160
1340
1000
1052
840
764
680
476
520
188
360
Da < 1
Maximum Temperature = 1200 K, 0 % of potential (cold flow)
A-A
A-A: x/D = 10
Da > 1
Maximum Temperature = 1715 K, 80 % of potential
Note maximum wall heat release at z/D = +/- 0.5
x/D = 10
-100
°F
200
K
18
CFD STUDY: B = 2.0 (LIFTED JET)
TOTAL TEMPERATURE CONTOURS — Tflame = 1840 K
2780
1800
2492
1640
2204
1480
1916
1320
1628
1160
1340
1000
1052
840
764
680
476
520
188
360
Da < 1
Maximum Temperature = 1200 K, 0 % of potential (cold flow)
x/D = 10
Da > 1
Maximum Temperature = 1683 K, 75 % of potential
Note maximum wall heat release at z/D = 0.0
-100
°F
x/D = 10
200
K
19
IN-LINE AND STAGGERED HOLE GEOMETRIES
Numerical studies extended to engine conditions
2500
B = 1.0, Da = 0.3, H* = 0.54, Qs ~ 0%
2100
1700
B = 1.0, Da = 0.3, H* = 0.54, Qs ~ 70%
1300
900 K
Staggered hole (z/D~3) at low B (0.5-1.0) provides ‘good’ surface
protection: burning is kept off-surface, h > 0.15
20
PERSONAL OBSERVATIONS
• Considering importance of combustion in society, it is somewhat surprising that
very few engineers have more than a cursory knowledge of combustion
phenomena
• MAE curriculum already packed at undergraduate level
• Engineers with some background in combustion may find many opportunities to
use expertise
• Aside from purely practical motivations for studying combustion, subject is
intellectually stimulating in that it integrates all of thermal sciences nicely and
brings chemistry into the practical realm of engineering
21
RESEARCH EXAMPLES
22
COMBUSTION RESEARCH AT FLORIDA TECH
• Phase 1 Development of a Combustion Prediction Capability for Sinda/Fluint
– Work with NASA KSC Launch Services Program
– Develop Independent Verification and Validation (IV&V) of liquid rocket
combustion process
• Delta II, Delta IV, and Atlas Rockets
23
COMBUSTION RESEARCH AT FLORIDA TECH
• Solid Rocket Motor Propellant Combustion and Plume Characterization
– Work with NASA KSC Launch Services Program
– Develop Independent Verification and Validation (IV&V) of solid rocket
combustion process
http://utias.utoronto.ca/~groth/research_rockets.html
http://monsoon.colorado.edu/~toohey/latest.html
24
COMBUSTION RESEARCH AT FLORIDA TECH
• 2007 Florida Centers of Excellent Proposal
– $50 M proposal to bring elevated combustion testing capability to Florida
– Primary partners Siemens and Florida Turbine Technologies
Area of Interest for Combustion Testing
Reproduce the same conditions that is expected in the engine in
terms of air, fuel, temperature, geometry, equipment.
Best data that can be obtained prior to testing in the engine.
25
COMBUSTION RESEARCH AT FLORIDA TECH
Inlet support piece.
Plate 1
area
coverage
BullHorn
Plate 4
area
coverage
Plate 2
area
coverage
Measuring section duct area
(inside)
Manhole
cover on
measuring
section
Plate 3
area
coverage
Note:
Traversing
cylinder not
installed in this
picture
Reproduce engine geometries (flow-box, row 1 vanes via VSS).
26
COMBUSTION RESEARCH AT SIEMENS
27

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