Guynn, Mark

Haller, William

NASA Technical Reports Server

1 
Subsonic Fixed Wing Project 
Fundamental Aeronautics Program 
Technical Challenges to Systems Analysis 
and MDAO for Advanced Subsonic 
Transport Aircraft 
AIAA Aerospace Sciences Meeting 
January 9-12, 2012 
 
William Haller and Mark Guynn 
Technical Leads for Systems Analysis & Integration 
Subsonic Fixed Wing Project 
 
William.J.Haller@nasa.gov 216-977-7004 
https://ntrs.nasa.gov/search.jsp?R=20150010336 2019-08-31T08:05:15+00:00Z
2 
Subsonic Fixed Wing Project 
Fundamental Aeronautics Program 
 
TC6 - Revolutionary tools and methods enabling practical design, 
analysis, optimization, & validation of technology solutions for vehicle 
system energy efficiency & environmental compatibility 
TC4 - Reduce harmful emissions attributable to aircraft energy 
consumption  
TC5 - Reduce perceived community noise attributable to aircraft with 
minimal impact on weight and performance 
TC1 - Reduce aircraft drag with minimal impact on weight (aerodynamic 
efficiency) 
TC2 - Reduce aircraft operating empty weight with minimal impact on 
drag (structural efficiency) 
TC3 - Reduce thrust-specific energy consumption while minimizing 
cross-disciplinary impacts (propulsion efficiency) 
SFW Strategic Thrusts & Technical Challenges 
Reduce 
TSEC 
Reduce 
OWE 
Reduce 
Drag 
Reduce 
Noise 
Reduce 
Emissions 
Economically 
Viable 
Revolutionary Tools and Methods 
Maintain 
Safety 
Enable Advanced Operations 
Energy Efficiency Thrust (with emphasis on N+3) 
Develop economically practical approaches to improve aircraft efficiency 
Environmental Compatibility Thrust (with emphasis on N+3) 
Develop economically practical approaches to minimize environmental impact 
Cross-Cutting Challenge (pervasive across generations) 
Energy & Environment 
TSEC 
Clean 
Weight 
Drag 
Noise 
Tools 
- Direct Impact 
- Indirect Impact 
3 
Subsonic Fixed Wing Project 
Fundamental Aeronautics Program 
 
NASA Subsonic Transport System Level Metrics 
…. technology for dramatically improving noise, emissions, & performance 
FAA/CLEEN                 NASA/ERA                  NASA SFW 
4 
Subsonic Fixed Wing Project 
Fundamental Aeronautics Program 
Active Flow 
Control 
Tailored Load 
Path Structure 
Designer 
Materials 
Turbulent CF 
Drag 
Reduction 
Diversified Portfolio Addressing N+3 Goals 
broadly applicable subsystems and enabling technologies 
N+3 
Vehicle 
Concepts 
N+3 
Subsystem 
Concepts 
Tailored 
 Fuselage 
 
High AR 
Elastic Wing 
 
Quiet, Simplified 
High-Lift 
 
High Eff. Small 
Gas Generator 
 
Hybrid Electric 
Propulsion 
 
Alternative 
Fuels 
 
Aerodynamic 
Configuration 
Tailored Load 
Path Structure 
Active Structural 
Control 
Adaptive, Lt Wt 
Fan Structure 
Hot Section 
Materials 
Distortion 
Tolerant Fan 
Gas-
Turbine/Electric 
Hybrids 
Fuel 
Properties 
Fuel-Flexible 
Combustion 
High-Lift 
System Noise 
Technical 
Areas Elastic Aircraft 
Flight Control 
Tip/Endwall 
Aerodynamics 
Tool Box – MDAO, System Modeling, Physics-Based Tools 
Aerodynamics 
Structure/Aero-
elastic/Materials 
Propulsion Combustion Acoustics MDAO 
Systems Analysis/ 
Conceptual Design 
Propulsion 
Airframe 
Integration 
Core Noise 
Decentralized 
Control 
Propulsion 
Airframe 
Aeroacoustics 
Designer 
Materials 
Aerodynamic 
Shaping 
Landing Gear 
Noise 
Aircraft Power 
Distribution 
Emission & 
Performance 
Acoustic Liners 
Transmission 
and Winding 
Materials 
TSEC 
Clean 
Weight 
Drag 
Noise 
Tools 
5 
Subsonic Fixed Wing Project 
Fundamental Aeronautics Program 
Active Flow 
Control 
Tailored Load 
Path Structure 
Designer 
Materials 
Turbulent CF 
Drag 
Reduction 
Diversified Portfolio Addressing N+3 Goals 
broadly applicable subsystems and enabling technologies 
N+3 
Vehicle 
Concepts 
Tailored 
 Fuselage 
 
N+3 
Subsystem 
Concepts 
High AR 
Elastic Wing 
 
Quiet, Simplified 
High-Lift 
 
High Eff. Small 
Gas Generator 
 
Hybrid Electric 
Propulsion 
 
Alternative 
Fuels 
 
Aerodynamic 
Configuration 
Tailored Load 
Path Structure 
Active Structural 
Control 
Adaptive, Lt Wt 
Fan Structure 
Hot Section 
Materials 
Distortion 
Tolerant Fan 
Gas-
Turbine/Electric 
Hybrids 
Fuel 
Properties 
Fuel-Flexible 
Combustion 
High-Lift 
System Noise 
Technical 
Areas Elastic Aircraft 
Flight Control 
Tip/Endwall 
Aerodynamics 
Tool Box – MDAO, System Modeling, Physics-Based Tools 
Aerodynamics 
Structure/Aero-
elastic/Materials 
Propulsion Combustion Acoustics MDAO 
Systems Analysis/ 
Conceptual Design 
Propulsion 
Airframe 
Integration 
Core Noise 
Decentralized 
Control 
Propulsion 
Airframe 
Aeroacoustics 
Designer 
Materials 
Aerodynamic 
Shaping 
Landing Gear 
Noise Aircraft Power 
Distribution 
Emission & 
Performance 
Acoustic Liners 
Transmission 
and Winding 
Materials 
TSEC 
Clean 
Weight 
Drag 
Noise 
Tools 
SA&I Primary Focus Ar as 
Vehicle/Propulsion 
Assessments 
Enhanced Tools & 
Methods 
6 
Subsonic Fixed Wing Project 
Fundamental Aeronautics Program 
Envisioned Challenges – NASA Perspective 
Systems Analysis/Conceptual Design Tools & Methods: 
- Analyzing advanced/unconventional configurations using empirical-based  
  prediction methods (conventional architectures) 
- Limited/no uncertainty quantification 
- Development of rapid turnaround, physics-based design/analysis tools 
- Increased analysis efficiency – more accuracy with less time & effort 
- Greater automation with intelligent streamlining of design process 
MDAO Tools & Methods: 
- Establishing standard interfaces between discipline tools 
- Lack of mid-fidelity codes to bridge gap between low & high fidelity  
- High computational costs for hi-fidelity tools limit number of function evaluations 
- Optimization performance comparisons based on standardized test problem set  
- Difficulty w/interfacing analysis environments to commercial CAD tools  
- Common (tool independent) geometry interface to build analysis tools around 
- Transition between multiple geometry engines as design process progresses 
7 
Subsonic Fixed Wing Project 
Fundamental Aeronautics Program 
 
Moving Forward 
• Over the past 6-9 months, SFW has identified technical challenges 
and then developed a strategic framework and tactical plans to guide 
project going forward 
 
• In support of the project’s objectives, Systems Analysis & Integration 
(SA&I) has several responsibilities: 
– Lead MDAO engineering framework development efforts 
– Develop new/enhanced conceptual design tools & methods 
– Conduct SFW’s technology assessments 
 
• Therefore, the sub-project structure consists of 3 critical elements 
– MDAO Tools & Methods 
– Systems Analysis/Conceptual Design Tools & Methods 
– Advanced Concepts: Modeling, Studies & Assessments   
 
 
8 
Subsonic Fixed Wing Project 
Fundamental Aeronautics Program 
MDAO Tools & Methods 
Focus: Develop an advanced, open source MDAO framework enabling 
the integration of multi-fidelity, multi-disciplinary design and analysis tools 
Technical Content: 
Open Source Framework Development (OpenMDAO): Continue development of 
open-source, Python-based multi-disciplinary engineering framework leading to 
initial “full” release (V1.0)  
 
Geometry Development: NRA-led activity focused on the development of a 
geometry handling capability within the OpenMDAO framework. (NRA 
participants – MIT & University of Michigan)  
 
MDAO Evaluation/Test Problem Formulation: Exercise existing OpenMDAO 
integration capabilities through a series of aerospace related test problems, 
included herein will be combustion & structure related activities 
 
GEN2 MDAO Framework Validation: Validation of ModelCenter-based framework 
by assessing predictive capability of integrated set of design/analysis tools on 
state-of-the-art commercial transport (B787) 
9 
Subsonic Fixed Wing Project 
Fundamental Aeronautics Program 
Sample of MDAO Tools & Methods Work (1) 
Conventional 
B737-800  
w/CFM56-7B26 engine 
Unconventional 
BWB-710  
w/advanced 3-shaft engine 
Metric % Diff Goal % Diff Goal
Takeoff Gross Weight -3.1% ± 5% +2.0% ± 15%
Range -0.1% ± 2.5% -1.2% ± 10%
Takeoff Field Length -4.2% ± 5% +7.1% ± 15%
Landing Field Length +2.3% ± 5% +10.7% ± 15%
LTO NOx -5.8% ± 5%
No Validation 
Data
± 15%
Avg EPNL +2.1 dB ± 2.5 dB
No Validation 
Data
± 7.5 dB
Conventional Unconventional
GEN2 MDAO Tool Suite Validation 
- 2nd generation capability developed primarily  
   to analyze unconventional systems 
- Validation completed by comparing aircraft  
  weight/performance for both configurations  
  against independent data sources  
- Predicted values met, or nearly met, accuracy  
  targets for all metrics for both architectures 
 
GEN2 MDAO Tool Suite - HWB 
Comparison of  Prediction vs. Available Data  
10 
Subsonic Fixed Wing Project 
Fundamental Aeronautics Program 
Sample of MDAO Tools & Methods Work (2) 
OpenMDAO Application Problem – Lean Direct Injection Combustor 
- Develop parametric-CAD approach for LDI combustor design 
- Quantify influence of key aerothermodynamic variables on individual & coupled  
  injector performance 
- Investigate parametric-CAD approach to Hi-Fidelity (CFD) design-by-analysis  
  addressing issues of geometry handling, automated meshing and Low/Hi-fidelity  
  code coupling 
 
Flow Diagram of Envisioned Process 
Geometry Handling 
11 
Subsonic Fixed Wing Project 
Fundamental Aeronautics Program 
Systems Analysis/Conceptual Design Tools & Methods 
Focus: Develop higher order design and analysis methods that enable reliable and robust 
exploration of conventional and unconventional concepts  
Technical Content: 
Robust Parametric Geometry Tools: Develop robust parametric geometry tools to achieve the 
best conceptual design capability and foster/improve the geometric tools internally to insure 
functionality to maximize tool effectiveness. (NRA participants – Cal Poly-SLO & Georgia Tech)  
 
Physics-Based Aerodynamic Design: Develop physics-based laminar flow/drag prediction tool 
that can be used in conceptual design process; investigate use of higher-order analysis methods 
to enable high-lift prediction tools suitable for system analysis/conceptual design. 
 
Weight Prediction Enhancements: Develop process to bridge gap between conflicting 
requirements for quick concept development/evaluation and need for design detail to support 
high-fidelity analysis enabling integration of higher fidelity structural analysis into the conceptual 
design environment. 
 
Physics-Based Aeromechanical Design: Enhance current engine flowpath/weight estimation tool 
(WATE++) by creating new modules that will represent some of components envisioned for N+3 
(e.g., turbo-electric). 
 
High-Fidelity MDAO for Highly Integrated Propulsion/Airframe: Develop quantitatively 
reliable/computationally efficient high-fidelity MDAO predictive capability for next generations of 
highly integrated propulsion & airframe configurations. 
12 
Subsonic Fixed Wing Project 
Fundamental Aeronautics Program 
Sample of Systems Analysis Tools & Methods Work 
High Fidelity MDAO for Highly Integrated Propulsion/Airframe  
- CFD simulation of the HWB configuration with embedded engines (N2B) 
- Provide aerodynamic characteristics of the complete configuration assessing the  
  impact on propulsion system performance (incl. Boundary Layer Ingestion)  
- Design optimization for  
 BLI inlet distortion/total pressure recovery   
 Integrated airframe-nacelle configuration 
Flow Separation Visualization 
Distortion Visualization 
Outboard Inlet/Engines Center Inlet/Engines 
Flow Streamlines 
13 
Subsonic Fixed Wing Project 
Fundamental Aeronautics Program 
Advanced Concepts 
Focus: Model/assess advanced propulsion and airframe technologies to advance 
knowledge and understanding of a diverse collection of airliner concepts that move beyond 
the conventional vehicles of today 
 
Technical Content: 
SUGAR Phase II NRA Collaboration: Work in concert with NRA partners (Boeing, GE 
Aviation, VA Tech & GA Tech) to understand/independently assess N+4 reference and 
advanced technology concepts. In addition, provide an independent assessment of N+3 
refined Truss-Braced Wing concepts and hybrid electric concepts. 
 
Turbo-electric Distributed Propulsion: Enhance NASA’s Turbo-electric Distributed 
Propulsion concept (N3-X) through further refinement of current in-house models to 
increase confidence of fuel burn reduction potential; in addition, perform acoustic and NOX 
emission assessments.  
 
Open Rotor Integration Study: Enhance current open rotor assessment through high-fidelity 
modeling capability to improve understanding of installation effects on open rotor 
performance.  
 
Conceptual Assessment of Pressure Gain Combustion: Perform conceptual level 
assessment of the potential benefits, and technology challenges, of pressure gain 
combustion for commercial transport engines. 
14 
Subsonic Fixed Wing Project 
Fundamental Aeronautics Program 
• SFW has been conducting an on-going engine trade study to assess 
propulsion options for advanced single-aisle (737/A320 class) aircraft 
– 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 
UHB Phase I: 
Initial Feasibility 
Study 
UHB Phase II: 
Engine Trade 
Study 
7/08 
UHB Phase IIb: 
Expanded/Refined 
Trade Study 
1/09 
UHB Phase IIc/IId: 
Refinement to 
select IIb engines 
10/09 
Open Rotor (OR):  
Initial Feasibility 
Study 
10/10 10/11 
Advanced Concept Work – Open Rotor 
• Recently completed assessment of open rotor concept  
- Collaborative effort (w/GE) utilizing modern blade set performance/aero  
- Initial comparison of fuel burn/noise delta vs. geared turbofan 
- Technical report/conference paper detailing results planned for 2012 
15 
Subsonic Fixed Wing Project 
Fundamental Aeronautics Program 
 
NASA Study Results – Fuel Burn vs. Noise 
162 Pax Airplane w/3250 nm design mission – Mcr = 0.78   
% Fuel Burn Benefit 
N
o
is
e
 M
a
rg
in
 
N+1 Tech 
Open Rotor 
BPR >30 
N+1 Tech 
UHB TF   
BPR ~14 
Baseline airplane: 
“stretched, aero updated” MD90-30 
~12 dB 
~9% Fuel Burn 
16 
Subsonic Fixed Wing Project 
Fundamental Aeronautics Program 
Advanced Concept Work – TeDP 
• Study conducted to compare potential of turbo-electric 
distributed propulsion (TeDP) on HWB architecture 
• Variants created (LH2-cooled & podded TF) for 
comparison 
• Preliminary fuel burn estimates tentatively meet N+3 
goal but warrants further detail design analysis  
• Next step involves investigation of concept’s acoustic 
& emission potential 
Summary of Fuel Burn Results – 3 Concepts 
TeDP Engine/Propulsor Description 
17 
Subsonic Fixed Wing Project 
Fundamental Aeronautics Program 
• SFW has identified technical challenges and developed strategic 
framework and tactical plans to guide project going forward 
• The project has created a diversified portfolio of technologies, with 
focus primarily (but not exclusively) in the N+3 timeframe 
• Systems Analysis & Integration (SA&I) support centered in 3 areas: 
– MDAO engineering framework development effort 
– Systems Analysis/Conceptual Design Tool & Methods Development 
– Vehicle/Propulsion Assessments 
• The sub-project is divided into 3 elements to address work: 
– MDAO Tools & Methods 
– Systems Analysis/Conceptual Design Tools & Methods 
– Advanced Concepts: Modeling, Studies & Assessments   
• Requisite work defined to address technical challenges  
• Several examples of recent accomplishments detailed 
Summary 
Fundamental Aeronautics Program 
Subsonic Fixed Wing Project 
19 
Subsonic Fixed Wing Project 
Fundamental Aeronautics Program 
What are we trying to do? 
• Improve the ability to assess the performance, environmental compatibility, and risk of conventional and 
unconventional aircraft configurations and advanced technologies 
Why? 
• Lack of robust, reliable capability to accurately design/assess unconventional technologies/concepts is an 
obstacle to revolutionary changes in current design paradigms 
• NASA needs ability to be an honest broker regarding the claimed advantages of unconventional 
configurations and advanced technologies 
• Better tools will foster greater creativity and innovation in aircraft design 
How is it done today, and what are the limits of current practice?  
• Use of lower order methods limits ability to accurately model new configurations/technologies  
• Successful use of higher order methods requires details not normally available in early design phases 
• Proprietary COTS MDAO frameworks make it difficult for outside developers to integrate new capabilities 
directly into architecture 
What is new in our approach?     
• Interjection of more physics into conceptual design process with focus on bridging the gap between high 
order analysis and high order design capabilities 
• Open source framework using Python programming language, enabling new tools to be constructed 
natively in framework 
• Open source licensing enables collaboration across MDAO community 
What are the payoffs if successful? 
• Broad opportunities for contributions from external MDAO researchers and greatly expanded capability for 
MDAO users 
• Ability to investigate new, innovative concepts with higher degree of confidence 
• Better informed decisions regarding investment in unconventional concepts and technologies 
Rationale for Working Tools & Methods Development 


Technical Challenges to Systems Analysis and MDAO for Advanced Subsonic Transport Aircraft

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