Document
Overview of Fundamental High-Lift
Research for Transport Aircraft at NASA
L . D . L e a v i t t , A . E . W a s h b u r n , R . A . W a h l s
N A S A L a n g l e y R e s e a r c h C e n t e r
C E A S C o n f e r e n c e , 1 0 - 1 3 S e p t . 2 0 0 7
B e r l i n , G e r m a n y
Presentation Outline
NASA Aeronautics Overview
History
Configurations
Current Technology
Devices and Technology concepts
CFD Status
Concluding Remarks
NASA ’ s New Aeronautics Research Program
Our Three Principles
• We will dedicate ourselves to the mastery and intellectual stewardship of
the core competencies of Aeronautics for the Nation in all flight regimes
• We will focus our research in areas that are appropriate to NASA ’ s
unique capabilities
• We will directly address the fundamental research needs of the Next
Generation Air Transportation System (Next Gen) in partnership with the
member agencies of the Joint Planning and Development Office (JPDO)
NASA ’ s New Aeronautics Research Program
• F u n d a m e n t a l A e r o n a u t i c s P r o g r a m – Subsonics : Fixed Wing – Subsonics : Rotary Wing – Supersonics – Hypersonics • A v i a t i o n S a f e t y P r o g r a m – Integrated Vehicle Health Management – Integrated Resilient Aircraft Control – Integrated Intelligent Flight Deck – Aircraft Aging & Durability • A i r s p a c e S y s t e m s P r o g r a m – NGATS Air Traffic Management: Airspace – NGATS Air Traffic Management: A irportal • A e r o n a u t i c s T e s t P r o g r a m – Ensure the strategic availability and accessibility of a critical suite of aeronautics test facilities that are deemed necessary to meet aeronautics, agency, and national needs
F u n d a m e n t a l A e r o n a u t i c s P r o g r a m
S u b s o n i c F i x e d W i n g P r o j e c t
Fay C ollier, P rincipal Investigator
June 2007
S F W A e r o d y n a m i c s - C E S T O L E m p h a s i s
NextGen Challenge - Accommodate 2-3X Growth in Air Travel by 2025 • Barriers include capacity/congestion, noise, emissions • Fuel Efficiency remains a vehicle constraint - becoming more important Key Aircraft Capability • STOL (field length ! 3000 ft) with low noise and efficient high-speed cruise (Mach 0.8+) • Specific d esign trades left to end-user Key Aircraft Technology • Powered Lift/Flow Control Concepts for Reduced Field Length • Efficient Cruise Configuration/Component Concepts for R educed Fuel Burn Key Tools • 3D Powered Lift/Flow Control Prediction/Design Tools (CFD - separation onset/progression) • 3D Powered Lift/Flow Control Test/Validation Capability (WT - relevant Mach and R n ) Key Partnerships for Tool & Technology Development/Validation • NRA PI ’ s at Level 1/2 • NASA/AFRL/Industry at Level 3/4
H is to ry
NASA High-Lift History
• P owered Lift* *From Chambers “ I nnovations in Flight, SP-2005-4539
! V G - S t r e a m w i s e V o r t i c i t y a t f r a c t i o n o f T B L "
E f f i c i e n t m e a n s o f c o n t r o l l i n g f l o w s e p a r a t i o n R e d i r e c t s h i g h e n e r g y f l o w i n t o b o u n d a r y l a y e r H e i g h t o f μ V G s o n t h e o r d e r o f 0 . 2 h / !
Piper Malibu Application - enabled FAA certificaiton M o d e l S c a l e F u l l S c a l e 1 . 0 m m 5 . 1 m m h 7 . 1 m m 3 5 . 6 m m l h ! VG l
A S T P r o g r a m H i g h - L i f t E l e m e n t ( 1 9 9 4 - 2 0 0 0 )
• O b j e c t i v e D e v e l o p i m p r o v e d e x p e r i m e n t a l a n d c o m p u t a t i o n a l t e c h n i q u e s w h i c h c a n p r o v i d e i n c r e a s e d 3 - D h i g h - l i f t s y s t e m u n d e r s t a n d i n g a n d a n a l y s i s a n d e n a b l e s s i g n i f i c a n t r e d u c t i o n i n h i g h - l i f t a e r o d y n a m i c d e s i g n c y c l e t i m e .
F u l l - s p a n t r a p w i n g m o d e l i n t h e A R C 1 2 ’ P W T 5.2% B777 in NTF High Wing Transport in ARC 12 ’ PWT
C o n fig u ra tio n s
ATT
Pneumatic Channel Wing
AFRL/NASA ESTOL Partnership
F l o w C o n t r o l o n t h e A d v a n c e d T a c t i c a l T r a n s p o r t ( A T T ) • Boeing Advanced Theater Transport • Forward-swept, tilt-wing, 4-engine turboprop • Deliver large payloads (80K lbs) on very short (750 ft) and unimproved landing sites • Requires Active Separation Control to achieve high lift goals for short takeoff and landing with simple hinged flap system R u n w a y I n d e p e n d e n t A i r c r a f t T a c t i c a l T r a n s p o r t
S i m p l i f i e d H i g h L i f t – A T T / A D V I N T
Goals for Active Flow Control (deltas 1 1 % A T T M o d e l i n from powered no-flow-control data) 1 4 - b y 2 2 - F o o t T u n n e l • Take-off, 40 deg flaps # C L = 0.2 goal • Landing, 50-60 deg flaps # C L = 0.5 goal C o n t r o l O n : F l a p s e p a r a t i o n d e l a y e d L a n d i n g G o a l A c t u a t o r s i n f l a p T a k e - O f f G o a l
P n e u m a t i c C h a n n e l W i n g
M e r g i n g P r o v e n T e c h n o l o g i e s Custer Channel Wing Circulation Control Wing (CCW) Utilizations R e m o t e s i t e s R o u g h F i e l d s U r b a n E n v i r o n m e n t s f o r * M i l i t a r y * P e r s o n a l A i r V e h i c l e s * C o m m e r c i a l Pneumatic Channel Wing Patented by E nglar a nd Bushnell
P n e u m a t i c C h a n n e l W i n g
M T F 0 6 3 , O u t b o a r d C C W B l o w i n g E f f e c t s , P r o p O N ; C T = 2 . 2 , C m u C h W = 0 , 1 . 0 , C C W F l a p = 0 ° , T a i l O F F 1 0 C μ L E = 0 . 4 9.5 P r o p O N , C T = 2 . 2 , C μ C h W = 1 . 0 , CCW LE Blowing C h a n n e l 8.5 P n e u m a t i c s A n d C μ L E = 0 . 0 C C W B l o w i n g O n 7.5 N o C h a n n e l S t a l l , No Outb'd Stall= C h a n n e l F l o w 6.5 E n t r a i n m e n t C μ L E = 0 . 2 C L C μ L E = 0 . 2 .
C μ L E = 0 . 0 5.5 C μ ! E = 0 . 2 C P e r f o r m a n c e B e n e f i t s L P r o p O N , C T = 2 . 2 , 4.5 C μ C h W = 0 . 0 , C C W B l o w i n g O n CCW LE Blowing 4 4 • O n d e m a n d h i g h - l i f t : 3.5 • C = 9 ( f u l l w i n g ) P r o p O F F , C m u C h W = 0 . 0 L 2.5 C μ L E = 0 . 4 • C = 1 0 . 5 ( i s o l a t e d c h a n n e l ) C h a n n e l S t a l l ?
L N o t O u t b ' d W i n g 1.5 o • S t a l l a n g l e s > 4 5 C μ L E = 0 . 0 0.5 P n e u m a t i c s O f f • R a p i d t a k e - o f f -0.5 • L o w - s p e e d , s t e e p l a n d i n g a p p r o a c h -1 -10 -5 0 5 10 15 20 25 30 35 40 45 50 5 0 0 1 0 2 0 4 0 3 0 A l p h a , d e g • P n e u m a t i c r o l l / y a w m a n e u v e r a b i l i t y Alpha, deg
A F R L / N A S A E S T O L P a r t n e r s h i p
T e c h n o lo g ie s
Slotted Wing (High Lift Aspects)
Circulation Control Wing (CCW)
Flow Control
Cruise Slotted Wing - W ave drag
• Complex viscous flow interactions
– s l o t f l o w , w a k e , s c a l e e f f e c t , s h o c k / b l , e t c
• Multidisciplinary trades and integration
– m u l t i p l e C F D c y c l e w i t h e x p e r i m e n t a l v e r i f i c a t i o n
• Key Findings
– P e r f o r m a n c e b e n e f i t i s a c h i e v a b l e i n 3 D S h o c k m o v e s a f t – C F D c o r r e l a t i o n w i t h e x p e r i m e n t n e e d s i m p r o v e m e n t s l o t t e d # M = 0.03 B a s e l i n e S l o t t e d W i n g S h o c k l o c a t i o n # M L/D = 1 s u p e r c r i t i c a l
S l o t t e d W i n g D e v e l o p m e n t
Technical Accomplishment W i n d t u n n e l d a t a f r o m L T P T W i n d t u n n e l d a t a f r o m L T P T High Lift System Integration for High Lift System Integration for M = 0 . 2 , R e = 9 x 1 0 M = 0 . 2 , R e = 9 x 1 0 Swept Slotted Wing Configurations Swept Slotted Wing Configurations 4 . 5 F l a p , V a n e , & V C K F l a p , V a n e , & V C K C r u i s e c o n f i g u r a t i o n C r u i s e c o n f i g u r a t i o n F l a p & V C K F l a p & V C K 3 . 5 C r u i s e c o n f i g u r a t i o n w i t h C r u i s e c o n f i g u r a t i o n w i t h v a n e v a n e 2 . 5 l c F l a p a n d V a r i a b l e C a m b e r 2 F l a p a n d V a r i a b l e C a m b e r K r u e g e r ( V C K ) K r u e g e r ( V C K ) C r u i s e c o n f i g u r a t i o n C r u i s e c o n f i g u r a t i o n 1 . 5 F l a p , V a n e , a n d V C K F l a p , V a n e , a n d V C K 0 . 5 - 0 . 5 - 5 0 5 1 0 1 5 2 0 ! ( d e g r e e s ) H i g h L i f t I n t e g r a t i o n w i t h C r u i s e S l o t t e d W i n g C o n c e p t C r u i s e C r u i s e I n t e g r a t i o n c o n c e p t s C r u i s e w / v a n e C r u i s e w / v a n e T E : S i n g l e / M u l t i - e l e m e n t ( v a n e ) L E : V a r i a b l e C a m b e r K r u e g e r F l a p a n d V C K F l a p a n d V C K F l a p , V a n e , a n d V C K F l a p , V a n e , a n d V C K
• Many benefits, few issues
– A p p r o a c h C L : m a n y o p t i o n s a v a i l a b l e – L a n d i n g C L m a x : s h o r t c h o r d f l a p s m a y r e d u c e C L m a x , b u t f l i g h t R n m a y h e l p – L o w S p e e d L / D : c o n t i n u o u s s p a n f l a p s p r o v i d e l a r g e b e n e f i t s
N A S A N R A w i t h B o b E n g l a r , G e o r g i a T e c h R I
• O b j e c t i v e : C r e a t e a n e w , m o r e c o m p l e t e d a t a b a s e t o s y s t e m a t i c a l l y q u a n t i f y e f f e c t s o f s l o t h e i g h t , m a s s f l o w , j e t v e l o c i t y . P r o v i d e p h y s i c a l u n d e r s t a n d i n g .
• C o l l a b o r a t i v e e f f o r t i n t w o f a c i l i t i e s – P a r a m e t r i c s t u d i e s a t G T R I M R F – L i m i t e d c o n d i t i o n f l o w f i e l d m e a s u r e m e n t s a t N A S A L a R C • 3 y e a r e f f o r t – Y e a r 1 : t e s t h a r d w a r e f a b r i c a t e d , p a r a m e t r i c F & M a n d C p d a t a , c o m p l e t e Q A o f m o d e l , L a R C f a c i l i t y m o d s , C F D c a l c u l a t i o n s – Y e a r 2 : d e t a i l e d f l o w f i e l d m e a s u r e m e n t s @ L a R C B A R T , L E b l o w i n g F & M a n d C p d a t a , C F D c a l c u l a t i o n s – Y e a r 3 : t r a n s o n i c d a t a a c q u i r e d
C i r c u l a t i o n C o n t r o l W i n g ( C C W ) T e c h n o l o g y
Wake turbulence as function of C !
• M i n i m u m w a k e a t t r a n s i t i o n f r o m
s e p a r a t i o n c o n t r o l t o s u p e r -
c i r c u l a t i o n
Current CFD status for 2-D CCW Predictions
• Many isolated successes using RANS have been reported, depending on case – But usually only for lower blowing rates – At higher blowing rates, CFD tends to predict separation too late (flow wraps around trailing edge too far) – Most successful turbulence model (NASA L aRC e xperience) has been SARC ( S palart-Allmaras w ith rotation-curvature correction), b ut inconsistent!
• Other methods (DES/LES) too preliminary to draw firm conclusions • Some issues: – Strong sensitivity of results to numerical parameters for these cases – Potential sensitivity to transition within the jet – Some conditions will require time-accurate computations – Uncertainties in boundary conditions used to match experiment – Loss of two-dimensionality in the experiment at higher blowing conditions – Most experiments very old – new experiments needed – Separation sensitive to turbulent kinetic energy, k – Limited effort on RANS modeling for transition implies k starts off incorrectly – Shear and streamline curvature shut off/change sign of production of k, models do not or at best badly represent Rumsey ( L aRC ) , S hariff e t.al.(ARC)
Coupled URANS + LES/DNS Simulation at ARC
N o v a k A i r f o i l O v e r l a p r e g i o n L E S / D N S U R A N S d o m a i n d o m a i n R e c y c l i n g A B A : M e a n v e l o c i t y f r o m t i m e - a v e r a g e d L E S / D N S s o l u t i o n ; C o n v e c t i v e o u t fl o w c o n d i t i o n f o r t u r b u l e n c e v a r i a b l e s .
B : M e a n v e l o c i t y f r o m R A N S ; V e l o c i t y fl u c t u a t i o n s f r o m t h e r e c y c l i n g p r o c e d u r e ( L u n d 1 9 9 8 )
Currently using two codes : OVERFLOW and CDP
( S hariff , et.al. N ASA ARC)
Preliminary CDP RANS Simulation (v2-f model)
N o v a k A i r f o i l , M = . 1 2 , C μ = 0 . 0 3
Vorticity c ontours + Streamlines ( $ = -2.46 deg)
$ = -2.46 deg. C = 1.5 (Exp); 1 .42 (CDP v2-f model)
L LES currently running.
AFC for Simplified High Lift
Motivated by study(s) indicating benefits of simplified
high lift systems
• L a r g e B e n e f i t o f A F C o n 2 D N A C A 0 0 1 5 w i t h f l a p a t H i g h R e • Z M F a c t u a t i o n e f f e c t i v e , n o c o m p r e s s e d a i r s o u r c e r e q u i r e d ?
• E v a l u a t e p o t e n t i a l f o r a c t i v e s e p a r a t i o n c o n t r o l t o e n a b l e s i m i l a r p e r f o r m a n c e t o c o n v e n t i o n a l 3 - e l e m e n t s y s t e m s Efficiency of ZMF on NACA 0015 at High Re
• NASA EET High Reynolds Number SHL model
• D r o o p e d l e a d i n g e d g e i s 1 5 % o f c h o r d a n d s i m p l e h i n g e d f l a p i s 2 5 % o f c h o r d • 1 2 % t h i c k s u p e r c r i t i c a l a i r f o i l • I n t e r n a l a n d e x t e r n a l a c t u a t i o n f o r L a R C L o w T u r b u l e n c e P r e s s u r e T u n n e l 1 . M c L e a n e t a l . , N A S A / C R - 1 9 9 9 - 2 0 9 3 3 8 , J u n e 1 9 9 9
Previous Work on SHL
2.5 -4 Baseline + F =12 -3 Flap Slot #3 -2 C C p l -1 1.5 Actuation Locations Baseline, no control Leading edge, Trailing edge, & Flap Leading edge, & Flap 1 0 0.2 0.4 0.6 0.8 1 0 5 10 15 x/c ! , deg
• Low Re (0.75 x 10 ) , small model
• Using LE, TE, and Flap actuation
(0.4 m chord), " =30°
improved the lift performance
f • Using actuator combinations, – 2 5 % a t a p p r o a c h a n g l e s o f a t t a c k
studied effects of
– 6 % i n C l m a x – E x c i t a t i o n w a v e f o r m ( S i n e , A M , P M ) – C o n t r o l s e n s i t i v e t o a c t u a t i o n l o c a t i o n – E x c i t a t i o n p h a s e a n g l e ( T E a n d F l a p ) a n d p h a s e a n g l e – D u t y c y c l e
• Interaction at C i s very complex
l m a x
SHL at High Re in LTPT (to 9 x 10 )
Electromagnetic and p iezo Z MF actuators – A c t u a t o r p e r f o r m a n c e d e g r a d e d a t l a r g e R e d u e t o p r e s s u r e – A c t u a t o r s d i d n o t h a v e s u f f i c i e n t a u t h o r i t y t o a t t a c h f l a p a t # C # C Frequency Actuators d p l r e q u i r e d f l a p d e f l e c t i o n s 75 Hz +5% +6% F2,F3 • M u l t i p l e e x c i t a t i o n l o c a t i o n s i m p r o v e p e r f o r m a n c e 75 Hz -3% +6% TE, F2, F3 Based on calibrated actuator authority, results consistent with l ow Re data 150 Hz -10% +0% F2, F3 – R e p l a y s a k e y r o l e i n b a s e f l o w b u t n o t i n A F C p h y s i c s 150 Hz -7.5% +3% TE, F2, F3 • L o c a t i o n o f a c t u a t i o n d e t e r m i n e d b y b a s e f l o w – C i r c u l a t i o n c o n t r o l l e d b e t t e r a t l o w f r e q u e n c i e s , s e p a r a t i o n a t h i g h e r f r e q u e n c i e s – S c a l i n g p a r a m e t e r s f o r A F C a n d a c t u a t o r s a r e c r i t i c a l 150 Hz excitation A I A A 2 0 0 7 - 0 7 0 7 , P a c k - M e l t o n e t a l ( N A S A ) A I A A 2 0 0 7 - 4 4 2 4 , K h o d a d o u s t & W a s h b u r n ( B o e i n g )
CFD Validation of Unsteady Flows
• T u r b u le n t S e p a r a t io n C o n t r o l o f F lo w o v e r W a ll- m o u n t e d
H u m p M o d e l ( A I A A 2 0 0 4 - 2 2 2 0 G r e e n b l a t t a n d o t h e r s )
– Case 3 of CFDVAL workshop. Includes baseline flow, steady
suction, ZMF oscillatory control
– Systematic evaluation of capability of URANS
s i d e p l a t e s y CFD c ases compared to baseline experiment z , W in C FDVAL G l a s s S l o t P l e n u m S p l i t t e r y , V R a m p p l a t e F o r e b o d y Model c x , U Side View
Streamlines (workshop cases)
Steady suction Oscillatory control
e x p e x p 0 . 1 c 0 . 1 c / / y y 0 . 0 5 0 . 0 5 s l o t s l o t 0 . 7 0 . 8 0 . 9 1 1 . 1 1 . 2 1 . 3 0 . 7 0 . 8 0 . 9 1 1 . 1 1 . 2 1 . 3 x / c x / c S A S A 0 . 1 c c 0 . 1 / / y y 0 . 0 5 0 . 0 5 s l o t s l o t 0 . 7 0 . 8 0 . 9 1 1 . 1 1 . 2 1 . 3 0 . 7 0 . 8 0 . 9 1 1 . 1 1 . 2 1 . 3 x / c x / c S S T S S T c 0 . 1 c 0 . 1 / / y y 0 . 0 5 0 . 0 5 s l o t s l o t 0 . 7 0 . 8 0 . 9 1 1 . 1 1 . 2 1 . 3 0 . 7 0 . 8 0 . 9 1 1 . 1 1 . 2 1 . 3 x / c x / c E A S M - k o E A S M - k o c 0 . 1 c 0 . 1 / / y y 0 . 0 5 0 . 0 5 s l o t s l o t 0 . 7 0 . 8 0 . 9 1 1 . 1 1 . 2 1 . 3 0 . 7 0 . 8 0 . 9 1 1 . 1 1 . 2 1 . 3 x / c x / c
Phase A veraged V orticity a nd Cp
+ - 1 S A F = 0 . 7 7 , < c > = 0 . 0 1 3 % μ S S T - 0 . 5 p E A S M - k o C e x p s l o t 0 . 5 0 . 6 0 . 8 1 1 . 2 1 . 4 1 . 6 x / c + + - 1 F = 0 . 7 7 , < c > = 0 . 3 5 4 % - 1 F = 0 . 7 7 , < c > = 0 . 0 1 3 % μ μ - 0 . 5 p - 0 . 5 p C C s l o t s l o t 0 . 5 0 . 5 0 . 6 0 . 8 1 1 . 2 1 . 4 1 . 6 0 . 6 0 . 8 1 1 . 2 1 . 4 x / c x / c + + - 1 F = 0 . 4 6 , < c > = 0 . 1 1 % - 1 F = 0 . 7 7 , < c > = 0 . 3 5 4 % μ μ - 0 . 5 - 0 . 5 p p C C C C p p 0 0 s l o t s l o t + 0 . 5 0 . 5 S A F = 0 . 7 7 , < c > = 0 . 0 1 3 % μ 0 . 6 0 . 8 1 1 . 2 1 . 4 0 . 6 0 . 8 1 1 . 2 1 . 4 1 . 6 x / c x / c S S T + + + S A - 1 F = 0 . 4 6 , < c > = 0 . 1 1 % = 0 . 7 7 , < c > = 0 . 0 1 3 % E A S M - k o - 1 F = 2 . 0 0 , < c > = 0 . 1 1 % μ μ μ S S T e x p - 0 . 5 - 0 . 5 p p E A S M - k o C C e x p s l o t
Use of RANS/URANS to Predict Trends
T h is w a s a n in v e s t ig a t io n s in t o t h e e f f e c t s o f R e y n o ld s
n u m b e r , c o n t r o l m a g n it u d e , a n d c o n t r o l f r e q u e n c y
• 3 t u r b u le n c e m o d e ls s im ila r , b u t S A m o d e l t e n d e d t o
a g r e e w it h e x p e r im e n t t h e b e s t
• S t e a d y s u c t io n : R A N S c a p a b le o f p r e d ic t in g t h e t r e n d s
d u e t o C ! ( b u t n o t a b s o lu t e le v e ls )
• O s c illa t o r y c o n t r o l: U R A N S d o e s n o t p r e d ic t t r e n d s d u e
t o C ! a n d F + in t h e m e a n v e r y w e ll, b u t s o m e p h a s e -
a v e r a g e d t r e n d s w e r e q u a lit a t iv e ly c a p t u r e d
• I t is a p p a r e n t t h a t L E S w ill b e r e q u ir e d t o im p r o v e t h e
p r e d ic t io n o f t h e v o r t e x s t r e n g t h / m a g n it u d e
3D Viscous CFD
3D CFD Viscous Prediction
E n a b l i n g O b j e c t i v e : E s t a b l i s h 3 D v i s c o u s p r e d i c t i o n c a p a b i l i t y f o r h i g h - l i f t s y s t e m s t h r o u g h C L m a x 3 . 1 0 3 . 2 5 E x p e r i m e n t 3 . 0 0 G r i d 2 G r i d 2 c “ T r a p W i n g ” G r i d 2 g G r i d F N B G r i d F 2 3 . 0 0 2 . 7 5 C C L L 2 . 5 0 2 . 9 0 2 . 2 5 2 . 0 0 2 . 8 0 1 . 7 5 2 8 1 0 1 5 2 0 2 5 3 0 3 5 4 0 ! , d e g .
Chaffin, NASA L aRC
Focus on Grid/Physics
In the linear region Near C lmax main wake is more important slat wake becomes more important increasing grid resolution
Lessons/Status
• Lessons: ! W a k e r e s o l u t i o n i s c r i t i c a l - C F D t e n d s t o o v e r p r e d i c t t h e v e l o c i t y d e f i c i t ! S u r f a c e g r i d r e f i n e m e n t i s n o t e n o u g h ! G r i d r e s o l u t i o n a r o u n d t h e s l a t i s i m p o r t a n t ! I t ’ s n o t a l w a y s t h e t u r b u l e n c e m o d e l ! G r i d n e e d s t o b e b e t t e r r e s o l v e d t o c a p t u r e b r a c k e t e f f e c t s ! G r i d g e n e r a t i o n i s t e d i o u s , b u t c o u l d p r o b a b l y b e a u t o m a t e d I f c e r t a i n g u i d e l i n e s r e g a r d i n g g r i d , t r a n s i t i o n , a n d t u r b u l e n c e m o d e l a r e f o l l o w e d , t h e n C p , C f , C l , a n d C d c a n b e p r e d i c t e d w i t h r e a s o n a b l e a c c u r a c y a t a n g l e s o f a t t a c k b e l o w s t a l l . C l m a x s t i l l a n i s s u e .
Current T echnical Challenges
massively large-scale problem sizes
• 1 07 million t etrahedra B777 Landing Configuration - N AS Columbia for grid generation - Months of run time - S till not able to predict C L ,max • Needs for grid g en .
- P arallelize VGRID - S olution adaptive grids • Needs for flow solvers - M ore processors - F aster algorithms - B etter turbulence models S h a h y a r . Z . P i r z a d e h @ n a s a . g o v T e t r U S S - Q uantification of uncertainty N e a l . T . F r i n k @ n a s a . g o v
Self-Adaptive analysis with known error bounds
A d j o i n t r e c o g n i z e s i m p o r t a n c e o f “ s m o o t h ” f l o w r e g i o n s A d j o i n t t e c h n i q u e i s c l e a r l y s u p e r i o r t o t r a d i t i o n a l a d h o c o r f e a t u r e b a s e d a p p r o a c h 2 D H i g h - L i f t E x a m p l e Adjoint-based Adaption (Lift) 24965 Nodes Pure Hessian-based Adaption 52235 Nodes C o u r t e s y V e n d i t t i & D a r m o f a l a t M I T ( u s i n g F U N 2 D )