IIT, Kanpur
Gas Turbine Combustion
and Power Generation
Dr. A. Kushari
Department of Aerospace Engineering
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Outline
•
•
•
•
•
•
•
Introduction
Advantages and Disadvantages
Future Requirements
Gas Turbine Combustors
Ongoing Research
Conclusions
Acknowledgement
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
TURBINES: Machines to extract fluid
power from flowing fluids
Steam
Turbine
Water
Turbines
Wind
Turbines
•High Pressure, High Temperature gas
•Generated inside the engine
•Expands through a specially designed TURBINE
Gas
Turbines
Aircraft Engines
Power Generation
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
GAS TURBINES
• Invented in 1930 by Frank Whittle
• Patented in 1934
• First used for aircraft propulsion in 1942 on Me262 by
Germans during second world war
• Currently most of the aircrafts and ships use GT engines
• Used for power generation
• Manufacturers: General Electric, Pratt &Whitney,
SNECMA, Rolls Royce, Honeywell, Siemens –
Westinghouse, Alstom
• Indian take: Kaveri Engine by GTRE (DRDO)
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
PRINCIPLE OF OPERATION
• Intake
– Slow down incoming air
– Remove distortions
• Compressor
– Dynamically Compress air
• Combustor
– Heat addition through
chemical reaction
• Turbine
– Run the compressor
• Nozzle/ Free Turbine
– Generation of thrust
power/shaft power
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Advantages and Disadvantages
• Great power-toweight ratio
compared to
reciprocating engines.
• Smaller than their
reciprocating
counterparts of the
same power.
• Lower emission
levels
• Expensive:
– high speeds and high operating
temperatures
– designing and manufacturing
gas turbines is a tough problem
from both the engineering and
materials standpoint
• Tend to use more fuel when
they are idling
• They prefer a constant rather
than a fluctuating load.
That makes gas turbines great for things like transcontinental jet aircraft and
power plants, but explains why we don't have one under the hood of our car.
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Emission in Gas Turbines
•Lower emission compared to all conventional methods (except nuclear)
•Regulations require further reduction in emission levels
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Needs for Future Gas Turbines
• Power Generation
– Fuel Economy
– Low Emissions
– Alternative fuels
• Military Aircrafts
– High Thrust
– Low Weight
Half the size and twice the thrust
• Commercial Aircrafts
–
–
–
–
Low emissions
High Thrust
Low Weight
Fuel Economy
Double the size of the Aircraft
and double the distance traveled
with 50% NOx
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Gas Turbine Combustion
F/A – 0.01
Combustion efficiency : 98%
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Ongoing Research
• Effect of inlet disturbances
• Combustion in recirculating flows
• Spray Combustion
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Effect of Inlet Disturbance
Tunable inlet to create weak disturbance of
varying frequency
Bluff body stabilized flame
Unsteady pressure and heat release
measurement
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Pressure Amplitude variation
 = 0.2211 L = 20 cm
•Pressure oscillations increases
with decreasing length
•Dominant frequency 27 Hz
•Acoustic frequency 827 Hz
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Pressure and Heat Release
Prms
Phase angle
330
160
150
140
Prms (pascal)
130
230
120
110
180
100
90
130
80
70
80
60
10
15
20
25
Length of Inlet (cm )
30
Phase angle (degree)
280
Less damping with increasing
length
Causes the rise is pressure
fluctuations
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Low Frequency Variation with Inlet
Length
Frequency
Amplitude
45
124
40
122
35
25
118
20
116
SPL (Db)
frequency (Hz)
120
30
15
114
10
112
5
0
110
10
15
20
25
30
Length of Inlet (cm )
ma  3.0 g / s ,  = 0.3455
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Variation of Dominant Frequency with Inlet Velocity
f *D
St  s
U
45
Frequency (Hz)
40
35
St = 0.171 (60 deg cone)
30
25
Measured
20
fs 
Calulated (St = 0.171)
15
0.171* U
0.02
10
0.8
1
1.2
1.4
1.6
1.8
2
Mean Inlet Velocity (m/s)
Dominant Frequency governed by vortex
dynamics
Feed back locking of flow instability and
combustion process
Phase relationship leads to
enhancement of combustion oscillations
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Ongoing Research
• Effect of inlet disturbances
• Combustion in recirculating flows
• Spray Combustion
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Recirculating Flow Dynamics
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•
•
•
•
•
Primary zone
Fuel air mixing
Intense combustion
Short combustion length
High turbulence
Fuel rich combustion
Understanding recirculating flow dynamics
Time scales
Pressure transients
Energy cascading
Combustion in recirculating flows
Droplet Flow interaction
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Image Processing
Filtered out image from the noises
Grayscale image
Intensity image
Simulation results
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
0.6
0.55
0.5
0.45
0.4
0.35
2.33
Vortex Dynamics
3.33
4.33
5.33
Non-dimensional time
6.33
Ratio of the second
vortex aera to the
total area of the cold
flowfield
Non-dimentional
distance(L2/L) of
second vortex to the
inlet of the combustor
IIT, Kanpur
0.01
0.008
0.006
0.004
0.002
0
2.33
3.33
4.33
5.33
Non-dimensional time
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
6.33
IIT, Kanpur
Transient Analysis
•Identification of signatures of re-circulation, turbulence and acoustics
through frequency domain analysis of pressure transients
•Turbulence energy cascading due to re-circulation
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Temperature in degree
centigrate
Non -dimensional
flame area
Combustion in Recirculating Flow
0.6
0.4
0.2
0
0
8
16
24
32
40
Non-dimensional time
48
56
450
400
350
300
250
200
0
0.2
0.4
0.6
0.8
1
Non-dimensional distance along the combustor diameter
Time scale reduces, complete combustion, Good pattern factor
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Ongoing Research
• Effect of inlet disturbances
• Combustion in recirculating flows
• Spray Combustion
–Needs and Challenges
–Controlled atomization
–Emissions in spray combustion
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Spray Combustion: Issues
• Non-symmetrical spray flames and hot
streaks
– Serious damage to combustor liner
– Combustor exit temperature (pattern factor)
• Flame location, shape and pattern
• Emission Levels
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Need for controlled atomization
– Big Drops => Longer Evaporation Time => Incomplete
Combustion => Unburned Hydrocarbons & Soot,
Reduced Efficiency
– Small Drops => Faster Evaporation and Mixing =>
Elongated Combustion Zone => More NOx
– Uniform size distribution for favorable pattern factor
• Reduced thermal loading on liner and turbine
– Reduced feedline coupling
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Ongoing Research
• Effect of inlet disturbances
• Combustion in recirculating flows
• Spray Combustion
–Needs and Challenges
–Controlled atomization
–Emissions in spray combustion
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Internally Mixed Swirl Atomizer
Good
atomization
with
small
pressure drop
Both hollow-cone and solid cone
spray from same atomizer
(wide range of applications)
Possible to atomize very viscous
liquid
Self cleaning
Finer atomization at low flow rates
Atomization of engine oil
Less sensitive to manufacturing
defects
The liquid flow rate and atomization
quality can be controlled
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Performance
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Multi-head internally mixed atomizer
•
Build to provide a throughput rate in excess to 0.5 LPM with a droplet
size in the range of 20-30 mm
2.5
LIQUID SUPPLY PRESSURE
y = 0.149x-0.9698
5 psi
10 psi
15 psi
20 psi
25 psi
Liquid Flow Rate (LPM)
2
1.5
1
90
LIQUID SUPPLY PRESSURE
80
0.5
70
5 psi
10 psi
15 psi
20 psi
25 psi
0
0
0.1
0.2
0.3
0.4
ALR
0.5
0.6
0.7
Flow rate independent of pressure
difference
Reduced feedline coupling
0.8
D32 (mm)
60
50
40
30
20
10
0
0
0.1
0.2
0.3
0.4
ALR
0.5
0.6
0.7
0.8
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Ongoing Research
• Effect of inlet disturbances
• Combustion in recirculating flows
• Spray Combustion
–Needs and Challenges
–Controlled atomization
–Emissions in spray combustion
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Emissions in spray flames
100
4500
90
4000
Exp
NOX (Theory)
Nox (ppm)
70
3500
3000
60
2500
50
2000
40
1500
30
1000
20
500
10
0
z=5mm
z=20mm
140
0.7
0.8
0.9
1
1.1
1.2
1.3

Distance from Flame Holder
Sauter Mean Diameter (mm)
0
0.6
160
NOx Theory (ppm)
80
z=10mm
z=35mm
•Measured values quite less
120
compared to the theoretical
predictions
•Inherent fuel staging reduces the
NOx
•Longer flame => less NOx
100
80
60
40
-1
0
1
2
3
4
5
Radial Distance from Center Line (cm)
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Conclusions
• Disturbances can lead to combustion
oscillations
• Recirculating flow helps in reducing
disturbances
• Controlled Atomization can be achieved
through air-assisting
• Spray combustion reduces NOx emissions
through fuel staging
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
Acknowledgements
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M. S. Rawat
S. K. Gupta
S. Pandey
P. Berman
J. Karnawat
S. Karmakar
N. P. Yadav
S. Nigam
R. Sailaja
M. Madanmohan
• Dr. K. Ramamurthi
• LPSC (ISRO)
• CFEES (DRDO)
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
IIT, Kanpur
THANK YOU
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.