Slide 1

National Aeronautics and Space Administration Optimization of Hybrid Wingbody Aircraft Meng-Sing Liou NASA Glenn Research Center Spring Progress in Mathematican and Computational Studies on Science and Engineering Problems May 3-5, 2014, National Taiwan University

Slide 2

A Tribute A cumulative effort, by postdocs and students under various NASA programs, developing and piecing together a set of necessary elements for performing MDAO. Akira Oyama Hyoungjin Kim Byung Joon Lee Justin Lamb Angelo Scandaliato Nick Stowe Weigang Yao Mattia Padulo May-Fun Liou SFW, SUP NASA Postdocs Program NASA USRP Knowledge Capabilities Applications

Slide 3

NASAs Technology Development Goals

Slide 4

Current Commercial Aircraft

Slide 5

Pros: lighter weight, higher lift to drag ratio, and lower fuel burn, reduced community noise Cons: aerodynamic interferences may reduce aerodynamic performance, propulsive efficiency and structural tolerance to distortion A complex system requires simultaneous consideration of of multiple disciplines and design objectives Hybrid Wingbody vs Current Aircraft N2-B Tube and wing Hybrid (blended) wingbody

Slide 6

Historical Development of HWB Vehicles Northrop YB-35, 1946 AirfoilAirfoil: NACA 65-019 root, NACA 65-018 tipNACA 65-019 Northrop YB-49, 1947 Northrop Gruman B-2, 1989

Slide 7

Historical Development of HWB Vehicles Boeing UCAV X-45C, 2002 Boeing UAV X-48, 2007 Burnelli CBY-3, 1955 Dassault nEUROn, 2012 Commercial Transport ???

Slide 8

Hybrid Wingbody Aircraft N3-X HWB (hybrid wing body) configuration for N+3 requirements Turboelectric Distributed Propulsion Embedded fans driven by electric motors in a mail-slot nacelle Wingtip mounted superconducting turbo-generators Decoupling of generator and motor speeds Ingestion of upper surface boundary layer Expected to reduce fuel burn by more than 70% relative to Boeing 777-200LR Kim, H. and Liou, M.-S., AIAA-2013-0221.

Slide 9

Fuel Efficiency and Noise Data Expected improvement by 26% But

Slide 10

Challenges Integration of propulsion and airframe Inlet ingesting thick boundary layer, resulting in a considerably distorted flow with total pressure loss at the compressor face Significant loss in aerodynamic performance resulting from their mutual interferences

Slide 11

N2-A N2-B N3-X HWB Configurations Studied by NASA Boeing UAV X-48, 2007

Slide 12

Outline of Presentation Integrated Configuration Mitigation of inlet flow distortion and loss of propulsive efficiency Aerodynamic analysis and optimization for N2-B and N3-X

Slide 13

Hybrid Wing Body Aircraft: N2B N2-B Impact on Propulsion System: Thick low-momentum layer ingested into inlet, Significant distortion and Total pressure loss at AIP Boundary-Layer Ingestion Horseshoe vortex, Lip flow separation Non-uniform flow at AIP S-bend separation, Secondary flow Advantages : Reduced ram drag Reduced structural weight Reduced wetted area Reduced noise Increased propulsive efficiency Flow Features in Embedded Boundary Layer Ingestion (BLI) Inlet Hybrid wing- body Forces : Viscous stresses Streamwise adverse pressure gradient Centrifugal force

Slide 14

BLI Inlet Allen et al. Vortex generator Wall bleeding

Slide 15

Taming Distortion and Losses in BLI Inlets Alternative way to conventional flow control, without incurring system losses. Shape optimization: properly conditioning the flow before it entering the inlet. Yu the Great Xia Dynasty

Slide 16

Design Optimization: Problem Statement Design Condition M 0 =0.85, Re 0 =3.8mil., A 0 /A c =0.533 BL thickness : 35% of Inlet Height Design Variables Control Points on the NURBS Patch, -1.8 x/D 0.5 Liou, M.-S. and Lee, B. J., Minimizing Inlet Distortion for Hybrid Wing Body Aircraft, ASME J. Turbomachinery, Vol. 134, #3, 2012. Lee, B. J. and Liou, M.-S., Optimizing Shape of Boundary-Layer-Ingestion Offset Inlet Using Discrete Adjoint Method, AIAA J. Vol. 48, No 9, 2008-2016, 2010. Design Formulation Minimize : Subject to : z i : z coordinate of i th control point z L : limit of design variable (10% of Inlet Height)

Slide 17

Slide 18

Detailed Flow Structures: Near Inlet Throat Y/D=0.5 Plane Eliminated lip flow separation flow separation at lip Establishing a global pressure field, resulting in flow acceleration

Slide 19

Performance at Off-design Conditions Simultaneous improvements in total pressure recovery and distortion Superior performance is maintained by the optimized design at all off-design conditions

Slide 20

Oil Flow Patterns at Off-Design Conditions A 0 /A c =0.533A 0 /A c =0.401A 0 /A c =0.506 Baseline Model A 0 /A c =0.557 Optimized Model A 0 /A c =0. 523 A 0 /A c =0. 423

Slide 21

Inlet-fan Coupling Mitigate deficiency in traditional specification of outflow pressure condition for assessing the inlet performance Direct coupling of, hence specification by the fan operating condition Need for fan flow analysis Full-scale simulation Reduced-order modeling

Slide 22

Reduced-order Model for Fan Flow R4 Fan1/5-scaled model tested in NASA Glenn Research Center, 22 in. diameter and 22 blades Reduced-order model built based on the CFD solutions

Slide 23

The Need for Analyzing Integrated Configuration

Slide 24

Propulsion Model for N2-B

Slide 25

Effects of Propulsion System Installation

Slide 26

Impacts on Flowfield and Aerodynamic Performance

Slide 27

Inlet Performance

Slide 28

Design Optimization Nacelle geometry Minimize drag, and Minimize distortion

Slide 29

Drag Minimization

Slide 30

Distortion Minimization

Slide 31

N3-X Turbo-electric distributed propulsion (TeDP) Targeted benefits: fuel burn savings by 70% relative to Boeing 777-200LR, M=0.84

Slide 32

Why Electric Propulsion Exhaust of current airplanes, CO 2, NO x, particulates, contributes climate changes Noise mitigation Allowing solar energy as power source Solar Impulse II

Slide 33

Fan Model

Slide 34

Flowfield near and inside the propulsion system Centerplane of Outermost passage Symmetry place

Slide 35

Propulsion Performance

Slide 36

Design by Drag Minimization Optimized Baseline

Slide 37

Concluding Remarks & Outlook Using high fidelity analysis and optimization in early design phase can reveal areas of importance and shed insight on technological challenges. Have discovered an effective way to improve inlet performance, without sacrificing system efficiency. Geometry, geometry, geometry MDAO has received considerable emphasis, developed fast, and its future for prime time is very promising.

Slide 38

Leonardo di ser Piero da Vinci April 15, 1452~May 2, 1519, Florence, Italy

Slide 39

Thank you for your attention and Best wishes! http://www.youtube.com/watch?feature=play er_embedded&v=FWvgpngKIW4 http://www.solar-impulse.com/ Keep up your dream, Look up to those pioneering dreamers, and Follow their spirits.