Gas Turbine Combustion and Power Generation

1. IIT, Kanpur PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG. Gas Turbine Combustion and Power Generation Dr. A. Kushari Department of Aerospace Engineering

2. IIT, Kanpur PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG. Outline • Introduction • Advantages and Disadvantages • Future Requirements • Gas Turbine Combustors • Ongoing Research • Conclusions • Acknowledgement

3. IIT, Kanpur PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG. TURBINES: Machines to extract fluid power from flowing fluids Steam Turbine Water Turbines Wind Turbines Gas Turbines • High Pressure, High Temperature gas • Generated inside the engine • Expands through a specially designed TURBINE Aircraft Engines Power Generation

4. 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)

5. 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

6. 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.

7. 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

8. 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

9. IIT, Kanpur PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG. Gas Turbine Combustion F/A – 0.01 Combustion efficiency : 98%

10. IIT, Kanpur PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG. Ongoing Research • Effect of inlet disturbances • Combustion in recirculating flows • Spray Combustion

11. 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

12. Pressure Amplitude variation IIT, Kanpur PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG.  = 0.2211 L = 20 cm • Pressure oscillations increases with decreasing length • Dominant frequency 27 Hz • Acoustic frequency 827 Hz

13. IIT, Kanpur PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG. Pressure and Heat Release Less damping with increasing length Causes the rise is pressure fluctuations

14. IIT, Kanpur PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG. Low Frequency Variation with Inlet Length ,  = 0.3455

15. IIT, Kanpur PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG. Variation of Dominant Frequency with Inlet Velocity St = 0.171 (60 deg cone) Dominant Frequency governed by vortex dynamics Feed back locking of flow instability and combustion process Phase relationship leads to enhancement of combustion oscillations

16. IIT, Kanpur PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG. Ongoing Research • Effect of inlet disturbances • Combustion in recirculating flows • Spray Combustion

17. 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

18. IIT, Kanpur PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG. Image Processing Filtered out image from the noises Grayscale image Intensity image Simulation results

19. IIT, Kanpur PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG. Vortex Dynamics

20. IIT, Kanpur Transient Analysis PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG. • Identification of signatures of re-circulation, turbulence and acoustics through frequency domain analysis of pressure transients • Turbulence energy cascading due to re-circulation

21. IIT, Kanpur PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG. Combustion in Recirculating Flow Time scale reduces, complete combustion, Good pattern factor

22. 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

23. 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

24. 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

25. 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

26. 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 rates Less sensitive to manufacturing defects The liquid flow rate and atomization quality can be controlled Atomization of engine oil

27. IIT, Kanpur PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG. Performance

28. 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 mm Flow rate independent of pressure difference Reduced feedline coupling

29. 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

30. IIT, Kanpur Emissions in spray flames PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG. • Measured values quite less compared to the theoretical predictions • Inherent fuel staging reduces the NOx • Longer flame => less NOx

31. 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

32. 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. Acknowledgements

33. IIT, Kanpur PROPULSION LAB, DEPARTMENT OF AEROSPACE ENGG. THANK YOU