Sriram Ganesan & Mukul Atri Final Year B.Tech-M.Tech Dual Degree Students mentored by

1. NASA Environmentally Responsible Aviation Sriram Ganesan & MukulAtri Final Year B.Tech-M.Tech Dual Degree Students mentored by Dr. AbhijitKushari Department of Aerospace Engineering Indian Institute of Technology Kanpur

2. Presentation Outline • Baseline aircraft -Hybrid Wing Body Concept • Baseline Engine-GE90 • After Dilation • Geared Turbofan • Stator Noise Reduction • Lean Direct Injection Combustors • Spiroid winglets • Golf-ball wings • Weights estimate

3. Hybrid Wing Body Concept • Supercritical outer wing profile • Shorter landing gear via better tail clearance • Propulsive efficiency via Boundary Layer Ingestion (BLI) • 30% reduction in structural weight • Drooped leading edge device • Faired undercarriage for reduction in noise • Source : N+3 Aircraft Concept Designs and Trade Studies, Final Report

4. Variable Area Nozzle • Reduced jet noise during takeoff, landing • Low fan speed operation • Cruise: Pitch trim- minimizes profile drag • Approach : increased drag using thrust vectoring combined with elevons

5. GE 90 Engine Data • sd

6. Trade -Off Plots

7. Mixed Exhaust State of Art • Augmenters- Low bypass Turbofan Engines - Takeoff, climb and combat • Atomized fuel ignites the mixture • Annular Mixers - Shearing effect at stream interface - Low mixing efficiency • Forced Mixers - Intertwined chutes force mixing - High pressure losses Source : http://shirshosengupta.blogspot.com/ 2011/04/ jet-engines-101.html Courtesy of Pratt & Whitney

8. After Dilation 4) Bypass Duct 1) Diffuser 3 1 2 2) Mixing Zone 5) Bleed Valve 6 3) Nozzle 6) Iris Nozzle 4 5 • High pressure differential between core and bypass • Bleed Valve- controls bypass bleed factor κ • Iris nozzle-allows various modes of operation

9. Modes of Operation κ=0 κ=0.4 κ=0.8

10. Boundary conditions Inlet conditions: Bypass: Core : • P08=62689 Pa P05=38143 Pa • T08=291.97 K T05=576.69 K • P8=52848 Pa P5=37467 Pa Exit: • Pa=23900Pa • Ta=218 K

11. Temperature Profile • 2-d simulations conducted using ANSYS fluent • Mixing converts thermal energy to kinetic energy • Quick dissipation due to efficient turbulent mixing

12. Velocity Profile • Mixing at the interface • Bleed valve optimization • Uniformity of profile across exit

13. Pressure Profile • Propagation of Pressure fronts • Core expands to ambient pressure • Bypass flow exits in under-expanded state

14. Results

15. Summary • Significant reduction in jet noise. - proportional to 8th power of velocity gradient - 64% reduction in velocity gradient • 3.2% decrease in SFC for κ=0.9 • Noise due to internal mixing • Dynamic Instabilities • Materials & Actuators

16. Geared Turbofan • High BPR desired due to increase in SFC • Increase in fan diameter • Lower RPM operation required for preventing shock losses • Efficiency of LPC decreases at lower RPM • Planetary reduction gear box used

17. Benefits • Low FPR and bypass exit velocity • Low fan RPM, low fan noise and jet noise • High propulsive efficiency • Length reduction of low-pressure spool components like LPC, LPT and thus a reduction in engine weight • Relatively higher LPC and LPT efficiency than the normal turbofan engines

18. Stator Noise Reduction Source: E. Envia, M. Nallasamy, ‘Design Selection and Analysis of a Swept and Leaned Stator Concept’, Journal of Sound and Vibration (1999) 228(4), 793-836, Article No. jsvi.1999.2441

19. Stator Configurations • Leaned stator: tangential rotation about the baseline radial position • Swept Stator: axial rotation about the baseline radial position • Aft-position radial stator (APRF): stator position displaced by a distance equal to the distance between the leading edge of the rotor and the swept stator • Results of high-sweep angles(300) are marginally better than those of APRF • APRF requires only small changes to the engine

20. Results Noise reduction due to modification in blade *-Values are averaged over upstream and downstream for 2 X BPF tone

21. Lean Direct Injection Combustors • Injects fuel into multiple zones • Reduces local temperature • Allows lean combustion • LDI combustors reduce LTO NOx emissions by 15-20%

22. Golf-ball wings • Golf-ball wings + smart structures => flap-less wings • Actuation can produce “dimples” • Larger Clmax • Differentiated operation of actuators can eliminate the need for ailerons as well • Application is similar to that of vortex generators on wings Source: http://www.aerospaceweb.org/question/aerodynamics/q0215.shtml

23. Spiroid Winglets • Reduction of Induced drag • 10% reduction in fuel burn for short journeys • Testing on-going for long flights Source: Aviation Partners, http://www.aviationpartners.com/future.html

24. Weights Estimate

25. The desire to fly is an idea handed down to us by our ancestors who... looked enviously on the birds soaring freely through space... on the infinite highway of the air. -Wilbur Wright As we embark on the challenge of greener aviation, the envy remains and the quest continues……

26. Many thanks to • Dr. AbhijitKushari, our project mentor who contributed his time and knowledge for this design • Vivek and Anandh for their invaluable help in conducting the computational simulations • Dr. Elizabeth Ward for prompt responses to all the queries and concerns through out the project • Dean Resource Planning and Generation Office (DRPG) and Department of Aerospace Engineering, IIT Kanpur for travel support to attend the forum

27. References • N+3 Aircraft Concept Designs and Trade Studies, Final Report • http://www.pw.utc.com/products/commercial/purepower-pw1000g.asp • VivekSanghi and B. K. Lakshmanan 2002 “Optimum Mixing of Core and Bypass Streams in High-Bypass Civil Turbofan”, Journal of Propulsion and Power Vol 18, No.4, July-August 2002 • Pearson, H., “Mixing of Exhaust and Bypass Flow in a Bypass Engine,” Journal of Royal Aeronautical Society, Vol. 66, Aug. 1962, pp. 528–530 • Frost, T. H., “Practical BypassMixing Systems for Fan Jet Aero Engine,”The Aeronautical Quarterly, May 1966, pp. 141–160. • http://www.grc.nasa.gov/WWW/RT/RT1997/5000/5860harrington.htm • http://en.wikipedia.org/wiki/Propelling_nozzle#Iris_nozzles • http://en.wikipedia.org/wiki/Geared_turbofan (continued..)

28. C. Riegler, C. Bichlmaier ‘The Geared Turbofan Technology-Opportunities, Challenges and Readiness Status’, http://www.mtu.de/en/technologies/engineering_news/others/Riegler_Geared_turbofan_technology.pdf • Philip G. Hill, Carl R. Peterson , Mechanics and Thermodynamics of Propulsion • IlanKroo ,‘Drag due to Lift: Concepts for Prediction and Reduction’, , Annu. Rev. Fluid Mech. 2001. 33:587–617 • http://www.flightglobal.com/blogs/flightblogger/2008/06/spiroid-wingtip-technology-the.html • http://www.jet-engine.net/civtfspec.html • E. Envia, M. Nallasamy, ‘Design Selection and Analysis of a Swept and Leaned Stator Concept’, Journal of Sound and Vibration (1999) 228(4), 793-836, Article No. jsvi.1999.2441 • Richard P. Woodward, David M. Elliott, Christopher E. Hughes and Jeffrey J. Berton ‘Benefits of Swept-and-Leaned Stators for Fan Noise Reduction’, • www.stanford.edu/~cantwell/AA283.../GE90_Engine_Data.pdf