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

mentored byDr. Abhijit Kushari

Department of Aerospace Engineering

Indian Institute of Technology Kanpur

NASA Environmentally Responsible Aviation

2Team VAAYUNovember 15, 2011

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

3Team VAAYUNovember 15, 2011

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

4Team VAAYUNovember 15, 2011

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

5Team VAAYUNovember 15, 2011

GE 90 Engine Data

• sdCruise Take-off

Height (Km) 10.668 0

Mach No. 0.850 0RAMPR 1.590 1FPR 1.650 1.580LPCPR 1.140 1.100HPCPR 21.5 23OPR 40.44 39.97BPR 8.1 8.4

Cruise Takeoff

Ta 218.820 288.16

Pa 0.239 1.014

TIT (K) 1380.0 1592.0

ma(kg/s) 576.0 1350.0

Thrust (kN) 69.2 375.3

mf(kg/s) 1.079 2.968

SFC (mg/N-s) 15.6 7.91

Intake Fan Compressor Turbine Nozzle Combustion

Polytrophic Efficiency

0.980 0.930 0.910 0.930 0.950 0.99

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Trade -Off Plots

7Team VAAYUNovember 15, 2011

Mixed ExhaustState 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

8Team VAAYUNovember 15, 2011

After Dilation1) Diffuser

2) Mixing Zone

3) Nozzle 6) Iris Nozzle

5) Bleed Valve

4) Bypass Duct

• High pressure differential between core and bypass• Bleed Valve- controls bypass bleed factor κ• Iris nozzle-allows various modes of operation

12

3

4 5

6

9Team VAAYUNovember 15, 2011

Modes of Operation

κ=0 κ=0.4 κ=0.8

10Team VAAYUNovember 15, 2011

Boundary conditionsInlet 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

11Team VAAYUNovember 15, 2011

Temperature Profile• 2-d simulations conducted

using ANSYS fluent• Mixing converts thermal

energy to kinetic energy• Quick dissipation due

to efficient turbulent mixing

12Team VAAYUNovember 15, 2011

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

13Team VAAYUNovember 15, 2011

Pressure Profile• Propagation of Pressure fronts• Core expands to ambient

pressure• Bypass flow exits in

under-expanded state

14Team VAAYUNovember 15, 2011

ResultsEngine GE90 in cruise GE90 with κ=0.6 GE90 with κ=0.7 GE90 with κ=.9

Thrust(N) 69219 70439 70767 71432

SFC(mg/N/s) 15.588 15.318 15.247 15.105

Exit Velocity of Core/Mixer (m/s)

368 293.3 292.8 295.1

Exit Velocity of Bypass (m/s)

248 283.0 289.6 290.9

Exit Pressure of Core/Mixer (Pa)

24094 33606 33897 34110

Exit Pressure of Bypass

41649 36146 35421 35223

Exit area of Core/Mixer(m^2)

1.011 3.22 3.569 4.260

Exit area of Bypass(m^2)

3.593 1.384 1.035 0.344

Net Gain in Thrust - 1.76% 2.24% 3.2%

15Team VAAYUNovember 15, 2011

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

16Team VAAYUNovember 15, 2011

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

17Team VAAYUNovember 15, 2011

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

18Team VAAYUNovember 15, 2011

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

19Team VAAYUNovember 15, 2011

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

20Team VAAYUNovember 15, 2011

Results

Noise reduction due to modification in bladeLocation Swept only(300)

(dB)Sweep(300) + lean(-300) (dB)

Aft-position radial stator (dB)

Take-off 15 18 13

Approach 7 8 7

Cutback 13 17 15

Total 35 43 35

*-Values are averaged over upstream and downstream for 2 X BPF tone

21Team VAAYUNovember 15, 2011

Lean Direct Injection Combustors

• Injects fuel into multiple zones• Reduces local temperature• Allows lean combustion• LDI combustors reduce LTO NOx emissions by 15-20%

22Team VAAYUNovember 15, 2011

Golf-ball wings

• Golf-ball wings + smart structures => flap-less wings

• Actuation can produce “dimples”• Larger Cl max • 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

23Team VAAYUNovember 15, 2011

Spiroid Winglets

• Reduction of Induced drag• 10% reduction in fuel burn for short journeys• Testing on-going for

long flights

Profile

Drag

Skin friction drag

Induced drag

Total Drag

Source: Aviation Partners, http://www.aviationpartners.com/future.html

24Team VAAYUNovember 15, 2011

Weights EstimateComponent Weight (in kgs)

Fan Weight (Single Gear Drive Fan) 1296

Nacelle Weight 760

Compressor (3 LPC+12 HPC) 1564

Combustor 325

Turbine(4 LPT+3 HPC) 2506

Accessories & Others 500

Total Weight 6951

25Team VAAYUNovember 15, 2011

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……

26Team VAAYUNovember 15, 2011

Many thanks to• Dr. Abhijit Kushari, 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

27Team VAAYUNovember 15, 2011

References1. N+3 Aircraft Concept Designs and Trade Studies, Final Report2. http://www.pw.utc.com/products/commercial/purepower-pw1000g.asp 3. Vivek Sanghi 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

4. Pearson, H., “Mixing of Exhaust and Bypass Flow in a Bypass Engine,” Journal of Royal Aeronautical Society, Vol. 66, Aug. 1962, pp. 528–530

5. Frost, T. H., “Practical BypassMixing Systems for Fan Jet Aero Engine,”The Aeronautical Quarterly, May 1966, pp. 141–160.

6. http://www.grc.nasa.gov/WWW/RT/RT1997/5000/5860harrington.htm7. http://en.wikipedia.org/wiki/Propelling_nozzle#Iris_nozzles8. http://en.wikipedia.org/wiki/Geared_turbofan

(continued..)

28Team VAAYUNovember 15, 2011

9. 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

10. Philip G. Hill, Carl R. Peterson , Mechanics and Thermodynamics of Propulsion11. Ilan Kroo ,‘Drag due to Lift: Concepts for Prediction and Reduction’, , Annu.

Rev. Fluid Mech. 2001. 33:587–61712. http://www.flightglobal.com/blogs/flightblogger/2008/06/spiroid-wingtip-te

chnology-the.html13. http://www.jet-engine.net/civtfspec.html14. 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

15. Richard P. Woodward, David M. Elliott, Christopher E. Hughes and Jeffrey J. Berton ‘Benefits of Swept-and-Leaned Stators for Fan Noise Reduction’,

16. www.stanford.edu/~cantwell/AA283.../GE90_Engine_Data.pdf