Circulation Control NASA activities

National Aeronautics and Space Administration

Circulation Control – NASA activities

Dr. Gregory S. Jones Dr. William E. Millholen II Research Engineers

NASA Langley Research Center

Active High Lift and Impact on Air Transportation 11th –12th April 2011

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•

Background

– Terminology

• Low Speed Activities

– 2D CC physics – BART

– NTF Dual Calibration Nozzle test

– High Re 3D Powered Lift Semi-Span FAST-MAC

• High Speed Activities

– High Re 3D CC Cruise Semi-Span FAST-MAC

• Concluding Remarks

TODAY’S ROADMAP

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

CORNERS OF THE TRADE SPACE

N+1 (2015)*** Technology Benefits

Relative to a Single Aisle Reference

Configuration

N+2 (2020)*** Technology Benefits

Relative to a

Large Twin Aisle Reference Configuration

N+3 (2025)*** Technology Benefits

Noise

(cum below Stage 4) - 32 dB - 42 dB - 71 dB

LTO NOx Emissions

(below CAEP 6) -60% -75% better than -75%

Performance

Aircraft Fuel Burn -33%** -50%** better than -70%

Performance

Field Length -33% -50% exploit metroplex* concepts

*** Technology Readiness Level for key technologies = 4-6

** Additional gains may be possible through operational improvements

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CIRCULATION CONTROL TERMINOLOGY

• Circulation control devices are typically related to actively blown systems (e.g. pneumatic surfaces or blown flaps)

• Circulation control surfaces can have almost any curved shape • Circular TE - jet separation is not fixed

CIRCULATION CONTROL AERODYNAMICS

Technology/Physics

High momentum blowing slot

• direct augmentation of lift and drag • steady or unsteady blowing

Benefits

Simplified low-speed high-lift system • significant reduction in flap chord • replacement of complex fowler system • reduction in weight

High-speed applications • transonic drag reduction

• buffet boundary modification • maneuvering

New design trade studies

Braunschweig C_ C l 0 0.2 0.4 0.6 0 1 2 3 4 5 6 Exp FUN3D CFL3D TLNS3D CAN WE PREDICT CC PERFORMANCE

0 2 4 6 8 0 0.1 0.2 0.3 0.4 C C_l CFD Experiment C.J.NOVAK LV & Performance 1986 GACC Jones

CFD VALIDATION PROCESS FOR CIRCULATION CONTROL

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Reversing Mode High Lift Mode

Cruise Mode

PARTNERSHIPS FOR ADVANCING CIRCULATION CONTROL AERODYNAMICS

CFD

NASA (LaRC & ARC)

Universit

Cµ  

Cµ  

EXAMPLE OF PIV MEAN VELOCITY FOR INTERNALLY BLOWN FLAP

Cµ  

Cµ 

h/c=0.002

=0o

_FLAP =60o • PIV data highlight streamline characteristics for a

internally blown flap

• Steady blowing extends flow control beyond separation control to super-circulation control

• Mean or turbulence characteristics can be used to identify breakpoint between separation control and

super-circulation SUPER-C IRCULA TION SEPARA TION C ONTR OL

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WAKE TURBULENCE FUNCTION OF Cµ • Minimum wake at transition from

separation control to super- circulation

• Can be applied to Circular TE SU

PER-C IRCULA TION SEPARA TION C ONTR OL

CFD VALIDATION - 3-D JUNCTURE EFFECTS 0.0 0.5 1.0 1.5 2.0 0.00 0.25 0.50 0.75 1.00 Z/b U/U C=0.10 C=0.20 C=0.00 C=0.23 AR=3.26

Pitot Static x/c = 0.5 y/b =0.5 y = 1.0”

 C_l =5.09 JUNCTURE FLOW INFLUENCE ON TWO- DIMENSIONALITY INCREASES WITH BLOWING

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2D CC LESSONS LEARNED

• Experiment

–Measured slot height along span critical … Large Slot heights correspond to large models

–Small scale experiments plagued with 3D effects (Small AR leads to juncture flow influences in lift and drag)

–Pulsed blowing reduces mass flow requirements

–Classic wall corrections are inadequate for super-circulation conditions

• CFD

–CFD RANS codes over-predict CC airfoil lift performance

• Turbulence Modeling

• Grid Generation

• Need to eliminate boundary conditions and 2D modeling issues as source difference

–Limited experimental data base with appropriate boundary conditions for CFD benchmarking

• Must validate jet velocity profile and mass flow with experiment for a given NPR and jet total temperature

–3D CFD simulations being pursued to eliminate 2D modeling issues ( and q corrections)

3D HIGH REYNOLDS NUMBER CIRCULATION CONTROL AT NTF

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DUAL FLOW HIGH PRESSURE AIR DELIVERY FOR SEMI-SPAN MODELS IN THE NTF

Testing in air (120 o_{F) to mild cryogenic conditions (-50}o_F)



Tunnel Sidewall

Propulsion Simulation

VERIFICATION OF AIR STATION PERFORMANCE

The Dual Flow Nozzle Model was used to characterize the performance of the

new NTF air station

•Interchangeable suite of existing Stratford calibration nozzles are available

•Evaluate effect of mass flow on wind tunnel balance

•Verify standard operating procedures and safety systems w_I  P_{O (JET )}A_t g RT_{O (JET )} 2 (  1)       1 1 If NPR < (NPR)_C If NPR > (NPR)_C

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VERIFICATION OF AIR STATION PERFORMANCE

Predicted Nozzle Performance (T_o,j =-50o_{F, P}

o(tunnel) = 5 ATM) • Mass flow exceeded predicted nozzle performance

•High Flow Leg: 23 lbm/sec •Low Flow Leg: 9 lbm/sec

• System vibration exceed limits of Vortex flow-meters resulting in increased measurement uncertainties (from 0.5% FS to 3% FS) • Multiple Critical Venturi (MCV) flow-meter replaces Vortex flow-meter

3D AERODYNAMIC SCALE EFFECTS FOR CC

Fundamental Aerodynamics Subsonic Transonic - Modular Active Control

– Low-speed high-lift & transonic cruise – State-of-art aerodynamic design

– Open geometry

– Modular for future flow control concepts – Propulsion simulation can be added – Can be shared with industry for

cooperative research

HIGH LIFT

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PREDICTED AERODYNAMIC CHARACTERISTICS OF FAST-MAC

WING DESIGN (NO BLOWING) USING USM3D

FEATURES OF FAST-MAC MODEL ASSEMBLY HIGH LIFT CONFIGURATION w/ VMD Targets HIGH LIFT CONFIGURATION w/ BALANCE CALIBRATION BLOCK

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EXAMPLE OF HIGH LIFT PRESSURE PROFILE

PRELIMINARY NPR=1.5

60o _{Dual Radius Flap}

PREDICTED AERODYNAMIC CHARACTERISTICS OF FAST-MAC HIGH-LIFT WITH BLOWING USING USM3D

M=0.20, =25o_{, NPR=1.80,} Re=20x106

Predicted Streamlines at Maximum Lift Coefficient

M=0.20, Re=20x106

Blowing Off Blowing On

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CONCLUDING REMARKS

• We are working with Industry, University, and DOD partners to advance the state of the art in prediction techniques associated with Circulation Control.

• Low speed physics based experiments that emphasis off body measurements are being used to understand the limitations of experimental and CFD techniques associated with Circulation Control.

• The capability to test flow control and propulsion simulations is being established in the NTF with the capacity to perform Reynolds number effects testing using semi-span models.

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STATE OF THE ART IS IMPROVING

• Experiments

– Long history that includes small scale to flight demonstrations

– Limited data sets available for modern CFD

validation for fixed wing aircraft.

• CFD

– Comparisons of different techniques resulted in

inconsistencies of performance prediction (turbulence models, grid generation related to jets and wakes, etc)

– Need better prediction tools and high-quality

experimental data bases to quantify and optimize CC performance.

• 2004 CC Workshop conclusions related to fixed wing applications

– CC has not been implemented on production

aircraft (Why?)

• Conventional high lift systems meet the current take-off and landing requirements

• CC becomes a viable option for short

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Characteristics of the New NTF-117S Balance Balance completion/calibration

• enables transonic semi-span testing • initial fabrication in 1990s during AST