gas turbine combustion and power generation
DESCRIPTION
IIT, Kanpur. PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG. Gas Turbine Combustion and Power Generation. Dr. A. Kushari Department of Aerospace Engineering. IIT, Kanpur. PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG. Outline. Introduction Advantages and Disadvantages Future Requirements - PowerPoint PPT PresentationTRANSCRIPT
Gas Turbine Combustion and Power Generation
Dr. A. Kushari
Department of Aerospace Engineering
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Outline
• Introduction
• Advantages and Disadvantages
• Future Requirements
• Gas Turbine Combustors
• Ongoing Research
• Conclusions
• Acknowledgement
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
TURBINES: Machines to extract fluid power from flowing fluids
Steam Turbine
Water Turbines
Gas Turbines
Wind Turbines
Aircraft EnginesPower Generation
•High Pressure, High Temperature gas •Generated inside the engine•Expands through a specially designed TURBINE
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
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)
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
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
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Advantages and Disadvantages
• Great power-to-weight 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.
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Emission in Gas Turbines
•Lower emission compared to all conventional methods (except nuclear)•Regulations require further reduction in emission levels
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Needs for Future Gas Turbines
• Power Generation– Fuel Economy– Low Emissions– Alternative fuels
• Military Aircrafts– High Thrust– Low Weight
• Commercial Aircrafts– Low emissions– High Thrust– Low Weight– Fuel Economy
Half the size and twice the thrust
Double the size of the Aircraft and double the distance traveled with 50% NOx
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Gas Turbine Combustion
F/A – 0.01
Combustion efficiency : 98%
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Ongoing Research
• Effect of inlet disturbances
• Combustion in recirculating flows
• Spray Combustion
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Effect of Inlet Disturbance
Tunable inlet to create weak disturbance of varying frequency
Bluff body stabilized flame
Unsteady pressure and heat release measurement
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Pressure Amplitude variation
= 0.2211 L = 20 cm
•Pressure oscillations increases with decreasing length
•Dominant frequency 27 Hz
•Acoustic frequency 827 Hz
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Pressure and Heat Release
Less damping with increasing length
Causes the rise is pressure fluctuations
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
3.0 /am g s , = 0.3455
Low Frequency Variation with Inlet Length
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Variation of Dominant Frequency with Inlet Velocity
10
15
20
25
30
35
40
45
0.8 1 1.2 1.4 1.6 1.8 2
Mean Inlet Velocity (m/s)
Fre
quen
cy (
Hz)
Measured
Calulated (St = 0.171)
*sf DStU
St = 0.171 (60 deg cone)
0.171*
0.02sU
f
Dominant Frequency governed by vortex dynamics
Feed back locking of flow instability and combustion process
Phase relationship leads to enhancement of combustion oscillations
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Ongoing Research
• Effect of inlet disturbances
• Combustion in recirculating flows
• Spray Combustion
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Recirculating Flow Dynamics
• 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
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Image Processing
Filtered out image from the noises Grayscale image
Intensity image Simulation results
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Vortex Dynamics
0.350.4
0.450.5
0.550.6
2.33 3.33 4.33 5.33 6.33
Non-dimensional time
No
n-d
ime
nti
on
al
dis
tan
ce
(L2
/L)
of
se
co
nd
vo
rte
x t
o t
he
in
let
of
the
co
mb
us
tor
0
0.002
0.004
0.006
0.008
0.01
2.33 3.33 4.33 5.33 6.33
Non-dimensional time
Ratio
of t
he s
econ
d vo
rtex
aera
to th
e to
tal a
rea
of th
e co
ld
flow
field
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
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
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Combustion in Recirculating Flow
0
0.2
0.4
0.6
0 8 16 24 32 40 48 56Non-dimensional time
No
n -
dim
en
sio
na
l fl
am
e a
rea
200
250
300
350
400
450
0 0.2 0.4 0.6 0.8 1 Non-dimensional distance along the combustor diameter
Te
mp
era
ture
in d
eg
ree
c
en
tig
rate
Time scale reduces, complete combustion, Good pattern factor
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Ongoing Research
• Effect of inlet disturbances
• Combustion in recirculating flows
• Spray Combustion
–Needs and Challenges
–Controlled atomization
–Emissions in spray combustion
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
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
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
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
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Ongoing Research
• Effect of inlet disturbances
• Combustion in recirculating flows
• Spray Combustion
–Needs and Challenges
–Controlled atomization
–Emissions in spray combustion
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
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 ratesLess sensitive to manufacturing
defects The liquid flow rate and atomization
quality can be controlled
Atomization of engine oil
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Performance IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
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 m
y = 0.149x-0.9698
0
0.5
1
1.5
2
2.5
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
ALR
Liqu
id F
low
Rat
e (L
PM
)
5 psi10 psi15 psi20 psi25 psi
LIQUID SUPPLY PRESSURE
0
10
20
30
40
50
60
70
80
90
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
ALR
D32
( m
)
5 psi10 psi 15 psi20 psi25 psi
LIQUID SUPPLY PRESSURE
Flow rate independent of pressure difference
Reduced feedline coupling
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Ongoing Research
• Effect of inlet disturbances
• Combustion in recirculating flows
• Spray Combustion
–Needs and Challenges
–Controlled atomization
–Emissions in spray combustion
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Emissions in spray flames
0
10
20
30
40
50
60
70
80
90
100
0.6 0.7 0.8 0.9 1 1.1 1.2 1.3
Nox
(ppm
)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
NO
x Th
eory
(ppm
)
Exp
NOX (Theory)
40
60
80
100
120
140
160
-1 0 1 2 3 4 5
Radial Distance from Center Line (cm)
Sau
ter
Mea
n D
iam
eter
(m
)
z=5mm z=10mm
z=20mm z=35mm
Distance from Flame Holder
•Measured values quite less compared to the theoretical predictions•Inherent fuel staging reduces the NOx•Longer flame => less NOx
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
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
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
Acknowledgements
• 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)
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.
THANK YOU
IIT, Kanpur
PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.