Next Decade Commercial Aircraft Aerodynamics - Boeing

ROI 2009-0501-1167

The Next Decade in CommercialAircraft AerodynamicsAircraft Aerodynamics –

A B i P tiA Boeing Perspective

Mark GoldhammerMark Goldhammer

Chief AerodynamicistBoeing Commercial AirplanesSeattle, Washington, U.S.A.

Aerodays 2011Madrid, Spain31 March 2011

BOEING is a trademark of Boeing Management Company.Copyright © 2011 Boeing. All rights reserved.

3 a c 0

The next decade in commercial airplane aerodynamics – a Boeing perspective

Outline

Historical look at aerodynamic configuration design at Boeing

Driving factors for the future

Aerodynamic levers for the next decade Aerodynamic product technologies Aerodynamic tools, processes and capabilities Airplane configurations

Concluding remarks

Copyright © 2011 Boeing. All rights reserved. Aerodays 2011 | 2

The beginnings of the


commercial jet age at BoeingB i 367 80 ( i 1954)Boeing 367-80 (circa 1954) Prototype for KC-135, B707 family Boeing’s first low-swept-wing transport Configuration basis for the future: Wing-mounted pod engines Double-slotted Fowler flaps with LE Krueger flaps

(B707)(B707)

Boeing Stratocruiser (circa 1947) Straight wingStraight wing Piston-powered propellers Fowler flaps


Wing-mounted pod engines became f f


C fi ti l ti f th

the configuration of choiceConfiguration evolution of the Boeing family Swept-wing, pod-mounted

engines (2 or 4)

B737 Continually increasing

aerodynamic technologies: CFD advances Airfoil/wing technology advances

B767

LE/TE high lift device advances Lessons learned from earlier products Higher Reynolds number wind tunnel

testing

B747

Improved structural concepts More integrated wing/engine/pylon

configurations Relaxed stability

L d ll i ti

B777

Load alleviation Multidisciplinary optimization


B757 B787


Other configurations

Wing-mounted pod engines were not always selected Aft-mount allows lower-to-the-ground configuration Perhaps more efficient with then-current technology Odd number of engines (3)

B727

g ( ) Cabin noise and vibration challenges

DC-9


DC-10


Driving factors for future improvement

Boeing commitment:Each new commercial airplane generation delivers at least 15% improvement in CO2 emissions and fuel efficiency

se

Early jet airplanes

MORE FUEL

HIGHERdB

ative

fuel

us Noise dB

70% fuel improvement and reduced CO2

90% reduction in noise footprint

Rela

B

LESSFUEL

LOWERdB

New Generation jet airplanes

FUEL dB

EVENLOWEREVEN

LESS


Nose footprint based on 85 dBa.1950s 1990s 2010s

Further drag reduction is required for


future efficiency improvement

Core aircraft technologiesRelative contributors to

787 efficiency improvement*

For current aircraft configurations, remaining areas for significant fuel-burn improvement in next 10-20 years are:

Systems

Propulsion/propulsion integration Aerodynamic drag reduction Multi-disciplinary optimization

MaterialsEngines

Multi disciplinary optimization

Alternate aircraft configurations may allow further integrated improvementsMaterials

Aerodynamics

allow further integrated improvements from core technologies

Aerodynamics


*Improvements are relative to 767-300ER


Aerodynamic levers

A d i d t t h l iAerodynamic product technologies Airplane configurations


(3) Airplane ConfigurationsAerodynamic tools, processes, and capabilities


Aerodynamic levers





Aerodynamic product technologies

Laminar flowTurbulent skin friction reduction

Advanced transonic wing concepts

Active flow control

Advanced transonic wing concepts

Integration of advanced engine concepts

Relaxed stabilityMulti-disciplinary optimization

Advanced trailing edge

Advanced variable camber concepts

device conceptsAdvanced leading edge device concepts


camber concepts

Aerodynamic drag breakdown


and reduction potential

Viscous and lift-induced drag are dominant drag components for subsonic aircraft in cruiseDrag breakdown (typical)

Advances in materials, structures and aerodynamics enable significant lift i d d d d tiW d

Excrescence drag

lift-induced drag reduction Maximize effective span extension using

compositesI t d d i ti d i

Induced and trim drag

Wave drag

Incorporate advanced wing-tip devices

Viscous drag is remaining area with largest potential for further drag

g

largest potential for further drag reduction

Viscous drag


Laminar flow drag reduction


benefits and issues

Natural Laminar Flow (NLF) and Hybrid Laminar Flow Control (HLFC) demonstrated in aerodynamic flight tests Transition flow physics generally understoodTransition flow physics generally understood Scale and sweep affect laminar-flow application (NLF vs. HLFC) Continuous progress in analysis and design methods

Laminar flow reduces fuel burn, emissions and noise Benefit depends on scale of application Improved fuel burn allows smaller lighter quieter aircraft Improved fuel burn allows smaller, lighter, quieter aircraft Estimated net potential fuel burn benefit for subsonic transports ~ 5 – 12 %

L i fl li ti i Laminar flow application issues Manufacturing, certification, and operational requirements and impacts Drag benefit needs to be traded against increased weight, maintenance, cost,

reliability etc


reliability, etc.


Some laminar flow activities1990 1995 2000 2005

757 HLFC Wing HLFC 787757 NLF

1985

flight test WT test NLFNacelle

Flight test

SLFC Studies

Steps WT Tests

HLFCVLA studies

Wing HLFCWT test

F-16XL SLFCflight test Product Development trade study

Wind-Tunnel (WT) or flight test


p y

Nacelles shaped for natural laminar flow (NLF)


p ( )Committed to 787 in 2005

Nacelle contours optimized with laminar transition location as additional design parameter Structural design and manufacturing methods tailored for NLF benefit


Turbulent flow drag reduction


benefits and issues

Riblet technology has been demonstrated to passively reduce local turbulent skin friction ~6 % Tunnel and flight tests with riblet films conductedTunnel and flight tests with riblet films conducted Application constraints (shape, spacing, streamlining) are

understood

Ribl li i i d i`

Riblet application issues are not aerodynamic: Limited riblet shape and adhesive robustness over

operational life (hydraulic liquids, hail, dirt and impact) Appearance relative to standard paint and livery Appearance relative to standard paint and livery Time required to install, maintain, remove and re-apply


Boeing drooped-spoiler flap


gCommitted to 787 in 2005

767Double/single slotted with

787

Fowler motion 6-bar linkage

787Single/single slotted

Simple-hinged flap with drooping spoilers Fewer parts (reduced maintenance) Lower weight Smaller fairings


Facilitates small flap adjustments in flight

Boeing trailing edge variable camber


g g gCommitted to 787 in 2005

Inboard flapFlaperon Trailing edge variable camber allows

Outboard flapAileron

g g Load optimization Cruise drag optimization

In cruise, trailing edge elements are adjusted at regular intervals to minimize drag Simplified actuation system Small angle variations


Small angle variations Up and down movements


Active Flow Control (AFC)

AFCAFC

Example: Application concept study with AFC augmented wing high lift system(Reference NASA CR-1999-209338)

High lift configurationwith AFC actuators

AFC

Evaluating Active-Flow Control (AFC) actuator and integration concepts for simplified (lighter) systems with similar performance as traditional mechanical high-lift elements ( g te ) syste s t s a pe o a ce as t ad t o a ec a ca g t e e e ts Robust, reliable and low-maintenance AFC actuation to be developed and

demonstrated for commercial transport Key issues that affect application success for commercial aircraft are:Key issues that affect application success for commercial aircraft are: Actuator capability, robustness and noise System power, complexity and cost Failure modes and redundancy considerations


a u e odes a d edu da cy co s de at o s


Aerodynamic levers




Aerodynamic tools, processes


and capabilities

Computational fluid dynamicsComputational fluid dynamics

Wind tunnel testingWind tunnelCFDWind tunnel testing

Flight testing

tunnelAerodynamic

designand analysisFlight testing

Future aerodynamics engineers

and analysis

y gFlight testing



Computational Fluid Dynamics (CFD)

Faster, more capable, and less costly computing hardware Faster and better algorithms Higher fidelity flow physics modeledHigher fidelity flow physics modeled Expanding simulations towards edges of flight envelope Integration with structural and systems modeling (MDO) Integration with wind tunnel and flight testingIntegration with wind tunnel and flight testing



The future for wind tunnels

Wind tunnels will continue to play a significant role in commercial airplane aerodynamic development: Design verification ho

urs

-25 %

Tunnel testing time

Design verification Database collection CFD validation New technologies

Occ

upan

cy h

-30 %

New configuration concepts Reduction in testing time enabled by availability of

mature and “calibrated” CFD767

(1980)777

(1990)787

(2005)

O

Boeing’s primary wind tunnel evaluation criteria: Technical viability – can do the required

testing Productivity – complete required testing in a

timely mannertesting

Accuracy and Validation – results that can be trusted

A il bilit d d il bl h

timely manner

Reliability – keeps working without interruption

Security – privacy and confidentiality assured


Availability – ready and available when needed Cost efficiency – good value for the money


Types of wind tunnel testing

Configuration development testing Incremental and absolute aerodynamic coefficient data Cruise, high-lift, and flight envelope limit data Airframe noise Propulsion installation Tare and interference testing

Fl t l t Flow control concepts Alternate configurations will require significant additional testing

Database development testingAi l f Airplane performance

Stability and control including simulator database Aerodynamic loads throughout envelope

Specialized testing Specialized testing Full scale Reynolds number Thrust reversers Ground effect


G ou d e ec Ice accretion/ice effects

Primary wind tunnels used by


Boeing Commercial Airplanes (2000 and on)

Farnborough, UK

Mountain View, CA

Cologne, Germany

Gifu, JapanSeattle, WA

Philadelphia, PA

Le Fauga, France

Minneapolis, MN

Hampton, VA



Flight testing aerodynamic technologies

Flight testing for certificationFlight testing for development/evaluation of aerodynamic

technologiestechnologies Certain technologies are difficult to simulate on scaled models in tunnel Concept to be flight tested must integrate with test vehicle

Fli ht t ti t id ti l i Flight testing to provide operational experience

Natural laminar flow Quiet-Technology Demonstrator (QTD2)



Future aerodynamics engineers

Continuing education and on-the-job t i i

Encourage youth into science, technology, engineering training

Retain knowledge from retiring senior

engineering, math (STEM) careers

Nurture students

from retiring senior engineers

COLLEGE

u tu e stude tsthrough funded research, internships, scholarships, etc.

Industry/ academia collaboration Encourage programs

that teach teamwork


that teach teamwork, multi-disciplinary studies


Aerodynamic levers




Aerodynamic opportunities and


challenges on alternate configurations

Geometries tailored to enhance laminar

Advanced multi-disciplinary optimization

Aerodynamic surfaces designed for active flow control

to enhance laminar flow control

p

Skin friction control

Control configured empennage

Configuration optimized for noise

Induced drag reduction with novel non-planar wing configurations

Boundary-layer ingestion for increased propulsion efficiency

Incorporation of novel propulsion systems (e.g., open fan)


Advanced integration of aerodynamics, structures and systems

Alternate configuration concepts


gNew challenges for aerodynamic design

Aerodynamic tools and processes that have been refined for tube-and-wing fi ti t b d t d/ lib t d f l i l i ft fi ti


configurations must be updated/calibrated for non-classical aircraft configurations

Commercial airplane aerodynamics:


What is next?

Readiness ofReadiness ofadvanced aerodynamic

technologies

Future configurations

Market requirements

Further significant reduction in fuel burn, noise, and emissions

Regulatory requirements


ue bu , o se, a d e ss o s


Summary

Aerodynamics will be key contributor to the future of aircraft design Safety Efficiency Environmental compatibility

The next decade of challenges will be multidisciplinary New aerodynamic technologies are on the horizon Integration with structures, propulsion, and systems, enabled by further computationalIntegration with structures, propulsion, and systems, enabled by further computational

advances Manufacturability and maintainability to introduce flow control methods

Aerodynamic technologies, together with tools, processes, and people, will be keys to future advances


Next Decade Commercial Aircraft Aerodynamics - Boeing

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