Berton, Jeff

Fisher, Ken

Guynn, Mark

Haller, Bill

Thurman, Doug

Tong, Mike

NASA Technical Reports Server

Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 1 Approved for Public Release 
National Aeronautics and Space Administration 
NASA’s Turbofan Engine Concept Study for a 
Next-Generation Single-Aisle Transport 
2009 Annual Meeting 
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 
September 29-October 1, 2009 
Presentation to ICAO’s Noise 
 Technology Independent Expert Panel 
January 25, 2012 
National Aeronautics and Space Administration 
U.S.A. 
https://ntrs.nasa.gov/search.jsp?R=20150010335 2019-08-31T08:05:22+00:00Z
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 2 Approved for Public Release 
Contributors 
• Jeff Berton (NASA Glenn Research Center) 
• Ken Fisher (NASA Glenn Research Center) 
• Mark Guynn (NASA Langley Research Center) 
• Bill Haller (NASA Glenn Research Center) 
• Doug Thurman (NASA Glenn Research Center) 
• Mike Tong (NASA Glenn Research Center) 
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 3 Approved for Public Release 
Presentation Outline 
• Introduction 
• Baseline Vehicle 
• Engine Modeling 
• Airframe Modeling 
• Noise Modeling 
• Results and Trade-off Analysis 
• Summary 
 
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 4 Approved for Public Release 
NASA Subsonic Transport System Level Metrics 
…. technology for dramatically improving noise, emissions, & performance 
SFW Approach    
- Conduct Discipline-based Foundational Research 
- Investigate Advanced Multi-Discipline Based Concepts and Technologies 
- Reduce Uncertainty in Multi-Disciplinary Design and Analysis Tools and Processes 
- Enable Major Changes in Engine Cycle/Airframe Configurations 
 
 
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 
5 
Historical Look at SFW Propulsion Studies  
• SFW has been conducting an on-going engine trade study to assess 
propulsion options for advanced single-aisle (737/A320 class) aircraft 
– Multi-year, Multi-phase effort 
– Initial focus on ultra-high bypass ratio (UHB) turbofan concepts, followed by 
investigation of open-rotor engine architectures 
– Multiple interactions with industry over the years to obtain feedback 
– Numerous technical reports and conference papers produced, plus 1 journal article 
10/06 4/07 10/07 
Results reviewed 
with P&W 
UHB Phase I: 
Initial Feasibility 
Study 
UHB Phase II: 
Engine Trade 
Study 
7/08 
UHB Phase IIb: 
Expanded/Refined 
Trade Study 
Results reviewed 
with P&W 
Review w/ 
Williams 
Presentation at 
FAP Meeting 
1/09 
Detailed 
exchange w/ 
P&W 
UHB Phase IIc/IId: 
Refinement to 
select IIb engines 
6/09 10/09 
NASA TM 
(UHB IIb) 
FAP 
AIAA ATIO 
(UHB IIb) 
Open Rotor (OR):  
Initial Feasibility 
Study 
10/10 10/11 
NASA TM 
(UHB IId) 
OR Results 
reviewed with GE 
AIAA ATIO 
(OR) 
J. Aircraft 
(UHB IId) 
AIAA 
Acoustics 
(OR) 
AIAA 
Acoustics 
(UHB IIb) 
AIAA ATIO 
(UHB IId) 
ASME 
Turbo Expo 
(OR) 
ISABE 
(OR) 
FAP 
(OR) 
Approved for Public Release 
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 6 Approved for Public Release 
Baseline Vehicle Model 
• Model of CFM56-7B type engine developed at Glenn Research Center using the 
Numerical Propulsion Simulation System (NPSS) 
• Baseline 737-800 w/winglets airframe model developed in NASA’s FLOPS (Flight 
Optimization System) software 
– Publicly available geometry, weight data; proprietary low speed and cruise aerodynamic data 
– Minor calibrations performed to match available data 
• Overall mission performance modeled with FLOPS 
– minor calibration of fuel consumption performed to match published range capability 
• 737 model resized to assumed N+1 vehicle mission to provide a 1998 technology 
baseline vehicle 
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 7 Approved for Public Release 
737-800 Fuel Consumption Validation 
 
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o
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Range, nm
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Published
18,700 lb Payload
47,000 lb Payload
 
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Payload, lb
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1000 nm Range
2000 nm Range
3000 nm Range
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 8 Approved for Public Release 
Advanced Turbofan Trade Study 
• 12 different turbofan engines developed with NPSS and WATE using consistent 
technology assumptions and ground rules (not all combinations result in 
practical designs) 
– Engine Aero Design Point: Overall Pressure Ratio=42; M=0.80; 35,000ft 
– Fan Pressure Ratio varied (FPR= 1.3 to 1.7); bypass ratio set by jet velocity ratio at ADP 
– Fan drive approach varied (direct or geared); gearbox efficiency of 0.99 
– Fan exit nozzle type varied (fixed or variable area); surge margin target of 20%  
– Low spool compression work varied (“high” or “low”) 
• 2015-2020 entry-into-service assumed for technology projections 
– Advanced Materials: polymer matrix composites, Titanium aluminide, Titanium metal matrix 
composite, 5th generation nickel-based alloys 
– Turbine inlet (T4) & turbine rotor inlet (T41) temperatures increased over current technology   
– Advanced Low NOX combustor  (using NASA in-house Emission Index correlation representative 
of Lean Direct Injection architecture) 
• Engines designed to meet same thrust requirements at Aero Design Point (top-
of-climb) & rolling takeoff (M=0.25, SL) 
• Engines applied to a common advanced single-aisle transport (“ASAT”) airframe  
• Sensitivity of efficiency, emissions, and noise to engine design assessed 
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 9 Approved for Public Release 
Engine Trade Space 
Engine Fan Drive Fan Nozzle ADP FPR OPR 
LPC 
PR 
HPC 
PR 
Lo_dd_fpr1.4_VAN* Direct Variable M0.80/35kft 1.4 42 1.69 17.7 
Lo_dd_fpr1.5_fixed Direct Fixed M0.80/35kft 1.5 42 1.58 17.7 
Lo_dd_fpr1.6_fixed Direct Fixed M0.80/35kft 1.6 42 1.48 17.7 
Lo_dd_fpr1.7_fixed Direct Fixed M0.80/35kft 1.7 42 1.39 17.7 
Hi_dd_fpr1.4_VAN* Direct Variable M0.80/35kft 1.4 42 2.50 12.0 
Hi_dd_fpr1.5_fixed Direct Fixed M0.80/35kft 1.5 42 2.33 12.0 
Hi_dd_fpr1.6_fixed Direct Fixed M0.80/35kft 1.6 42 2.19 12.0 
Hi_dd_fpr1.7_fixed Direct Fixed M0.80/35kft 1.7 42 2.06 12.0 
Hi_g_fpr1.3_VAN* Geared Variable M0.80/35kft 1.3 42 2.69 12.0 
Hi_g_fpr1.4_VAN Geared Variable M0.80/35kft 1.4 42 2.50 12.0 
Hi_g_fpr1.5_fixed Geared Fixed M0.80/35kft 1.5 42 2.33 12.0 
Hi_g_fpr1.6_fixed Geared Fixed M0.80/35kft 1.6 42 2.19 12.0 
*Design ground rules lead to impractical designs for these cases 
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 10 Approved for Public Release 
0
2
4
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12
1.2 1.3 1.4 1.5 1.6 1.7 1.8
Top-of-Climb Fan Pressure Ratio
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ia
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Geared, High
Direct Drive, Low
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Top-of-Climb Fan Pressure Ratio
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Direct Drive, High
Geared, High
Direct Drive, Low
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0.47
0.49
0.51
0.53
0.55
0.57
0.59
1.2 1.3 1.4 1.5 1.6 1.7 1.8
Top-of-Climb Fan Pressure Ratio
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O
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S
F
C
, 
lb
/(
lb
-h
)
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Geared, High
Direct Drive, Low
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25
1.2 1.3 1.4 1.5 1.6 1.7 1.8
Top-of-Climb Fan Pressure Ratio
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O
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y
p
a
s
s
 R
a
ti
o
Direct Drive, High
Geared, High
Direct Drive, Low
Engine Characteristics 
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 11 Approved for Public Release 
-80%
-70%
-60%
-50%
-40%
-30%
-20%
-10%
0%
1.2 1.3 1.4 1.5 1.6 1.7 1.8
Top-of-Climb Fan Pressure Ratio
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T
O
 N
O
X
, 
re
la
ti
v
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o
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A
E
P
6
Direct Drive, High
Geared, High
Direct Drive, Low
0
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15
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25
30
1.2 1.3 1.4 1.5 1.6 1.7 1.8
Top-of-Climb Fan Pressure Ratio
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T
O
 N
O
X
, 
g
/k
N
Direct Drive, High
Geared, High
Direct Drive, Low
Engine Characteristics (2) 
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 12 Approved for Public Release 
Advanced Airframe Assumptions 
• Structures:  
– composite materials for wing, fuselage, and tails (15% structural weight 
benefit assumed) 
• Aerodynamics:  
– 1% reduction in drag for trailing edge variable camber and drag clean-up  
• Subsystems:  
– 5000 psi hydraulic pressure 
• Design range @ 32,400 lb payload increased from 3060 nm to 3250 
nm 
• Cruise Mach number increased to 0.8 
– Wing sweep adjusted to reflect changes in cruise Mach from 737 
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 13 Approved for Public Release 
Engine-Airframe Integration 
• Relative span-wise and chord-wise location of engine unchanged from 737-
800 
• Nacelle drag assumed proportional to nacelle size (wetted area) 
• Approximate calculation of required landing gear length  
– Minimum nacelle clearance (18 inches) 
– No nacelle impact in case of nose gear collapse 
• Approximate sizing of vertical tail 
– Minimum tail volume (based on 737-800) 
– Maximum tail loading during one engine out 
– Handbook method for windmilling drag, 737-800 data used for engine out control 
drag 
Example FPR=1.4 Configuration Example FPR=1.7 Configuration 
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 14 Approved for Public Release 
Aircraft Sizing 
• Aircraft weight, thrust, and wing area sized with FLOPS analysis 
– design mission: 3250 nm @ 32,400 lb payload 
– 7000 ft takeoff field length constraint 
– 300 fpm rate-of-climb constraint at M=0.80; 35,000 ft 
• Basic geometric parameters (e.g., fuselage length, wing aspect 
ratio, wing taper ratio, etc.) unchanged from 737-800 
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 15 Approved for Public Release 
Noise Analysis Methodology 
• Noise predictions performed using ANOPP 
– Source noise modules fed data from NPSS and WATE models 
– Propagation modeling includes spherical spreading, atmospheric attenuation, 
ground effects, reflections, and lateral attenuation 
• Trajectory simulation done using SAE AIR-1845 INM empirical procedures 
for a 737-800 and FLOPS for advanced vehicles  
• Noise predictions performed for noise certification points 
 
 
 
 
 
 
• Noise analysis validated by comparison to 737-800 certification data 
2000 m 
(6562 ft) 
Flyover 
Reference 
Lateral 
(Sideline) 
Reference 
Approach 
Reference 
6500 m 
(21 325 ft) 
450 m 
(1476 ft) 
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 16 Approved for Public Release 
Noise Analysis Validation 
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id
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All certificated B737s equipped with CFM56-7Bs
Validation B737 Prediction
Stage 3 Rule
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Maximum Takeoff Gross Weight (klb)
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All certificated B737s equipped with CFM56-7Bs
Validation B737 Prediction
Stage 3 Rule
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Maximum Takeoff Gross Weight (klb)
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All certificated B737s equipped with CFM56-7Bs
Validation B737 Prediction
Stage 3 Rule
Approach EPNL 
Lateral (Sideline) EPNL Flyover (Cutback) EPNL 
Comparison of predicted noise to published 737NG/CFM56-7B certification data 
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 17 Approved for Public Release 
ASAT Noise Reduction Technology 
• Core nozzle chevrons assumed on all systems, bypass nozzle 
chevrons on fixed nozzles only (potential conflict with variable area 
bypass nozzles) 
– Benefit analytically modeled using 2004 Stone jet prediction methods in 
ANOPP 
• Conventional 2DOF acoustic liner 
• Soft vane and over-the-rotor liner technologies applied to all 
systems 
– Additional acoustic treatment in areas not currently treated 
– ANOPP HDNFAN is insensitive to this feature; system-level 4 dB 
reduction applied 
– Benefits are additive, and assumed constant across frequency, 
direction, and throttle setting 
• Advanced airframe noise reduction technologies 
– Innovative slat cove designs, flap porous tips, landing gear fairings 
– 4 dB reduction in slat/flap noise; 3 dB reduction in gear noise 
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 18 Approved for Public Release 
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Top-of-Climb Fan Pressure Ratio
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 F
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Direct Drive, High
Geared, High
Direct Drive, Low
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Top-of-Climb Fan Pressure Ratio
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Direct Drive, Low
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Geared, High
Direct Drive, Low
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Top-of-Climb Fan Pressure Ratio
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Aircraft Characteristics 
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 19 Approved for Public Release 
-35.0
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h
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Geared, High
Direct Drive, Low
* Baseline is predicted 737-800 noise level
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 N
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lb
Direct Drive, High
Geared, High
Direct Drive, Low
Aircraft Characteristics (2) 
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 20 Approved for Public Release 
-35.0
-30.0
-25.0
-20.0
-15.0
-10.0
-5.0
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1.2 1.3 1.4 1.5 1.6 1.7 1.8
Top-of-Climb Fan Pressure Ratio
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u
m
u
la
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v
e
 E
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 M
a
rg
in
 r
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 S
ta
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 4
 R
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le
, 
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P
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Geared, High
Direct Drive, Low
Overall Benefits 
-30%
-25%
-20%
-15%
-10%
-5%
0%
1.2 1.3 1.4 1.5 1.6 1.7 1.8
Top-of-Climb Fan Pressure Ratio
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h
a
n
g
e
 i
n
 B
lo
c
k
 F
u
e
l*
Direct Drive, High
Geared, High
Direct Drive, Low
* Baseline is 1998 EIS Technology Airframe and Engine 
-16%
-14%
-12%
-10%
-8%
-6%
-4%
-2%
0%
1.2 1.3 1.4 1.5 1.6 1.7 1.8
Top-of-Climb Fan Pressure Ratio
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h
a
n
g
e
 i
n
 R
a
m
p
 W
e
ig
h
t*
Direct Drive, High
Geared, High
Direct Drive, Low
* Baseline is 1998 EIS Technology Airframe and Engine 
-80%
-70%
-60%
-50%
-40%
-30%
-20%
-10%
0%
1.2 1.3 1.4 1.5 1.6 1.7 1.8
Top-of-Climb Fan Pressure Ratio
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T
O
 N
O
X
, 
re
la
ti
v
e
 t
o
 C
A
E
P
6
Direct Drive, High
Geared, High
Direct Drive, Low
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 21 Approved for Public Release 
Trade-off Analysis 
Ramp Weight Block Fuel Block NOX  LTO NOX  
Cum. EPNdB 
(Stage 4 Margin*) 
High, Geared, FPR=1.4 +2.0 % +0.5% +2.7% Minimum 
Minimum 
(25-29 cum.) 
High, Geared, FPR=1.5 +0.3% Minimum +0.5% +0.5% 
+3.7 
(21-25 cum.) 
Low, Direct, FPR=1.5 +3.7% +2.3% +8.4% +10.6% 
+4.3 
(21-25 cum.) 
High, Direct, FPR=1.5 +6.8% +6.0% +7.3% +4.8% 
+4.4 
(21-25 cum.) 
High, Geared, FPR=1.6 +0.1% +2.0% Minimum +6.9% 
+10.3 
(14-18 cum.) 
Low, Direct, FPR=1.6 +0.5% +1.2% +4.5% +11.5% 
+10.4 
(14-18 cum.) 
High, Direct, FPR=1.6 +2.6% +3.9% +3.0% +6.9% 
+10.5 
(14-18 cum.) 
Low, Direct, FPR=1.7 Minimum +2.8% +3.4% +18.9% 
+16.1 
(9-13 cum.) 
High, Direct, FPR=1.7 +1.2% +4.5% +0.5% +12.7% 
+15.8 
(9-13 cum.) 
Good “balanced” performance across all metrics * Range represents uncertainty associated 
with possible overprediction of flyover noise 
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 22 Approved for Public Release 
Trade-off Analysis (Cont.) 
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C
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B
Block Fuel, lb
Hi_DD_1.5f
Hi_DD_1.6f
Hi_DD_1.7f
Lo_DD_1.5f
Lo_DD_1.6f
Lo_DD_1.7f
Hi_G_1.4v
Hi_G_1.5f
Hi_G_1.6f
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208
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B
lo
ck
 N
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, l
b
Block Fuel, lb
Hi_DD_1.5f
Hi_DD_1.6f
Hi_DD_1.7f
Lo_DD_1.5f
Lo_DD_1.6f
Lo_DD_1.7f
Hi_G_1.4v
Hi_G_1.5f
Hi_G_1.6f
80000
82000
84000
86000
88000
90000
92000
30000 30500 31000 31500 32000 32500
O
p
e
ra
ti
n
g 
Em
p
ty
 W
e
ig
h
t,
 lb
Block Fuel, lb
Hi_DD_1.5f
Hi_DD_1.6f
Hi_DD_1.7f
Lo_DD_1.5f
Lo_DD_1.6f
Lo_DD_1.7f
Hi_G_1.4v
Hi_G_1.5f
Hi_G_1.6f
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 23 Approved for Public Release 
Summary 
• SFW project has been performing aircraft system studies to evaluated 
advanced propulsion concepts for 2015-2020 advanced single-aisle transports 
• For advanced turbofans, optimum fan pressure ratio depends on metric of 
interest 
– Empty/Ramp weight minimized with high FPR 
– Block fuel minimized with FPR ~1.5 
– Block NOX minimized with high FPR 
– LTO NOX and noise minimized with FPR low as possible 
• With current models and assumptions 
– Fan pressure ratio with best compromise among all objectives seems to be ~1.5 
– Geared fan approach is preferred for fan pressure ratios at and below 1.5 
– A direct drive, FPR=1.6 engine can provide similar fuel burn to the geared FPR=1.5 
engine, but has higher noise 
• Relative to 1998 EIS technology, “practical” study configurations demonstrate 
– Up to 29% reduction in fuel burn 
– Up to 25 EPNdB cum. noise reduction (25-29* EPNdB cum. margin to Stage 4) 
– Up to 67% below CAEP6 for LTO NOX 
* Range represents uncertainty associated with possible overprediction of flyover noise 
Your Title Here 24 


NASA's Turbofan Engine Concept Study for a Next-Generation Single-Aisle Transport: Presentation to ICAO's Noise Technology Independent Expert Panel

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