Circulation Control NASA activities

Transcription

1 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

2 TODAY S ROADMAP EMPHASIS ON EXPERIMENTS FOR CFD VALIDATION 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 2

3 NASA Subsonic Transport System Level Metrics. technology for dramatically improving noise, emissions, & performance 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 Performance Field Length -33%** -50%** better than -70% -33% -50% exploit metroplex* concepts *** Technology Readiness Level for key technologies = 4-6 ** Additional gains may be possible through operational improvements * Concepts that enable optimal use of runways at multiple airports within the metropolitan areas 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 3

4 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 Internally Blown Flap - jet separation can be fixed to TE flap 4

5 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 field length (CTOL,STOL,ESTOL), noise, cruise efficiency, maneuver 5

6 CAN WE PREDICT CC PERFORMANCE GACC 8 6 CFD Experiment Exp FUN3D CFL3D TLNS3D C l 4 2 C.J.NOVAK LV & Performance 1986 C l C C Jones 6

7 CFD VALIDATION PROCESS FOR CIRCULATION CONTROL 7

8 PARTNERSHIPS FOR ADVANCING CIRCULATION CONTROL AERODYNAMICS NASA (LaRC & ARC) SUPERCRITICAL TMA0712 AIRFOIL SUPERCRITICAL GACC AIRFOIL TE BLOWING & PULSED TE BLOWING TE BLOWING TE BLOWING & PULSED Cruise Mode University LE BLOWING University of Florida GTRI TE BLOWING CFD High Lift Mode Reversing Mode DOD & Industry CAL POLY 8

9 EXAMPLE OF PIV MEAN VELOCITY FOR INTERNALLY BLOWN FLAP 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 supercirculation SUPER-CIRCULATION Cµ SEPARATION CONTROL Cµ Cµ Cµ h/c=0.002 =0 o FLAP =60 o 9

10 WAKE TURBULENCE FUNCTION OF Cµ Minimum wake at transition from separation control to supercirculation Can be applied to Circular TE SUPER-CIRCULATION SEPARATION CONTROL 10

11 CFD VALIDATION - 3-D JUNCTURE EFFECTS 2.0 JUNCTURE FLOW INFLUENCE ON TWO- DIMENSIONALITY INCREASES WITH BLOWING C l =5.09 AR= U/U C =0.10 C =0.00 C = Z/b Pitot Static x/c = 0.5 y/b =0.5 y = 1.0 C =

12 2D CC LESSONS LEARNED Experiment CFD 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 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) Introduces the need to resolve complex juncture flows at a significant simulation cost 12

13 3D HIGH REYNOLDS NUMBER CIRCULATION CONTROL AT NTF Aerial View of the LaRC National Transonic Facility 13

14 DUAL FLOW HIGH PRESSURE AIR DELIVERY FOR SEMI-SPAN MODELS IN THE NTF Tunnel Sidewall Propulsion Simulation Testing in air (120 o F) to mild cryogenic conditions (-50 o F) 14

15 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 If NPR < (NPR) C If NPR > (NPR) C w I P O( JET ) A t g 2 RT O (JET ) ( 1)

16 VERIFICATION OF AIR STATION PERFORMANCE 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 Predicted Nozzle Performance (T o,j =-50 o F, P o(tunnel) = 5 ATM) Nozzle Diamter:

17 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 60 o FLAP CONFIGURATION 17

18 PREDICTED AERODYNAMIC CHARACTERISTICS OF FAST-MAC WING DESIGN (NO BLOWING) USING USM3D Wing Designed using CDISC 18

19 FEATURES OF FAST-MAC MODEL ASSEMBLY HIGH LIFT CONFIGURATION w/ VMD Targets HIGH LIFT CONFIGURATION w/ BALANCE CALIBRATION BLOCK 19

20 EXAMPLE OF HIGH LIFT PRESSURE PROFILE PRELIMINARY NPR= o Dual Radius Flap h/c=

21 PREDICTED AERODYNAMIC CHARACTERISTICS OF FAST-MAC HIGH-LIFT WITH BLOWING USING USM3D Blowing On Blowing Off M=0.20, =25 o, NPR=1.80, Re=20x10 6 M=0.20, Re=20x10 6 Predicted Streamlines at Maximum Lift Coefficient 21

22 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. 22

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24 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 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 runways an Noise Abatement flight profiles 24

25 SCHEMATIC OF THE NTF AIR STATION 25

26 Characteristics of the New NTF-117S Balance Balance completion/calibration enables transonic semi-span testing initial fabrication in 1990s during AST parallel effort for in situ calibration at NTF 26