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Numerical Aeroelastic Simulation of Aircraft Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE, FRANCE www.DLR.de Chart 1 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

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Page 1: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Numerical Aeroelastic Simulation of Aircraft Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE, FRANCE

www.DLR.de • Chart 1 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 2: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 2

Flutter stability

Limit cycle oscillations

Forced Response

Gust response Wake vortex Tail buffeting

Vibration due to flow instabilities

Seperated flow

Bluff bodies Shock buffet

Aeroelasticity (relevant to fixed-wing aircraft)

Page 3: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 3

Flutter stability

Forced Response

Vibration due to flow instabilities

Aeroelasticity (relevant to fixed-wing aircraft)

Linear Frequency Domain Solver Laminar Flow, Shock Buffet Flutter Speed Flutter Analysis

1

2

4

3

Page 4: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 4

Linear Frequency Domain (LFD) Solver

Thormann / Widhalm IFASD 2013

www.DLR.de • Chart 4 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 5: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 5

Motivation LFD

Flutter, Gust Response

- analysed in frequency domain

- many parameter combinations have to be simulated

Accuracy of RANS required

RANS expensive

LFD could save time

www.DLR.de • Chart 5 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 6: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 6

Validation LFD

Assuming small amplitudes of motion

RANS equations can be linearized

Transformed into frequency domain

Validation of LFD:

LFD solution and RANS time domain solution

should be the same for small amplitudes

www.DLR.de • Chart 6 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 7: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 7

Validation case

-  Fermat-Model

-  4 · 106 grid points

-  Re = 5 · 106

-  Spalart-Allmaras turbulence model

-  Rigidly trimmed to CL = 0.5

-  2 Mach numbers considered:

-  0.85 and 0.89

steady flow characteristics

www.DLR.de • Chart 7 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 8: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 8

Unsteady results: Transfer function of CL

-  Good agreement between LFD and time-domain results for the attached case

-  Differences for the detached case -  LFD and time-domain solver should agree!

Mach = 0.85 Mach = 0.89

www.DLR.de • Chart 8 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 9: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 9

Computational Effort

Time Saving Factors:

Memory requirement:

no. of CPUs: 48

Case   TD  (h)   LFD  (h)   ζCPU  

Ma  =  0.85,  2.85  periods   33.4   0.38   88  

Ma  =  0.89,  3.09  periods   40.4   0.55   73  

solver   memory  (GB)   M  /  Msteady  

steady  RANS   7.20         1.00  

Mme  domain  RANS   7.58   1.05  

LFD   161.00   22.36  

www.DLR.de • Chart 9 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 10: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 10

Intermediate Results

-  Good agreement between LFD and time domain results

for the attached case

-  Larger deviations for the separated case

-  LFD and time domain solution should be same for

small amplitudes

www.DLR.de • Chart 10 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 11: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 11

Flutter stability

Forced Response

Vibration due to flow instabilities

Aeroelasticity (relevant to fixed-wing aircraft)

Linear Frequency Domain Solver Laminar Flow, Shock Buffet Flutter Speed Flutter Analysis

1

2

4

3

Page 12: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 12

Influence of transitional flows

on flutter speed

Michael Fehrs IFASD 2013

www.DLR.de • Chart 12 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 13: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 13

Background and Relevance

-  Increasing the laminar flow regime can reduce friction drag and improve the overall flight performance.

-  But: Influence of the laminar-turbulent boundary layer transition on the aeroelastic behavior is not known.

www.DLR.de • Chart 13 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 14: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 14

Investigation Set-up Aerodynamic Model: CAST 10-2 Airfoil -  CAST 10-2: supercritical (laminar) airfoil

-  CFD investigation with the DLR TAU code:

-  Ma = 0.500 up to Ma = 0.800 -  Rec = 2·106 with c = 0.3 m

-  unsteady analysis for αmean = 0.0°

-  Wind tunnel data shows large transitional regions for Re = 2·106 .

www.DLR.de • Chart 14 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 15: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 15

Flutter Diagram

How does the flutter boundary change in a transitional flow?

www.DLR.de • Chart 15 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 16: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 16

Transition Modeling in CFD

RANS models and transition prediction methods turbulence closure transition prediction flow type

SST k-ω model γ-Reθ model transitional

flow

SST k-ω model fully turbulent

flow

www.DLR.de • Chart 16 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 17: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 17

Investigation Set-up Aerodynamic Model: CFD grid ~ 60 000 nodes ~ 290 nodes on upper surface ~ 210 nodes on lower surface far field 100 chords away

www.DLR.de • Chart 17 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 18: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 18

Results Steady CFD Results: Ma = 0.720

non-linear lift region

lift gain through laminar flow

Lift curve

www.DLR.de • Chart 18 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 19: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 19

Results Steady CFD Results: Ma = 0.720

laminar bucket

drag penalty for fully turbulent flow

Drag polar

Page 20: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 20

Results Steady CFD Results: Ma = 0.720

strong influence of transition behavior on lift curve

www.DLR.de • Chart 20 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 21: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 21

Results Unsteady CFD results: Overview -  Focus on pitch results for:

-  Mach number: 0.720 -  6 reduced frequencies k -  fully turbulent (blue) and transitional flow (red)

-  Results in terms of magnitude |clα| and phase angle Φlα

www.DLR.de • Chart 21 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 22: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 22

Results Unsteady CFD results: clα Ma = 0.720: -  Different magnitude and phase

response for transitional flow

-  Aerodynamic resonance only found for transitional flow

transitional

fully turbulent

www.DLR.de • Chart 22 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 23: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 23

Results Unsteady CFD results: clα Resonance found in the non-linear lift region

www.DLR.de • Chart 23 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 24: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 24

Investigation Set-up Flutter Analysis and Structural Model

-  2 degree-of-freedom system: -  pitch motion around

quarter chord (x0 = 0) -  heave motion

-  classical bending-torsion flutter

www.DLR.de • Chart 24 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 25: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 25

Results Flutter Analysis

www.DLR.de • Chart 25 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 26: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 26

Results Flutter Analysis

Turbulent / Transitional flow: -  higher flutter stability for

given structural model outside the transonic dip with BL transition

-  but deeper transonic dip at lower Mach number with BL transition

www.DLR.de • Chart 26 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 27: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 27

Intermediate Results

-  CFD based flutter analysis for a supercritical airfoil (CAST 10-2): -  Fully turbulent and transitional simulations -  Re = 2e6, transonic flight regime

-  The transonic dip gets deeper and moves to a lower Mach number for a transitional flow.

-  The transitional flows show an aerodynamic resonance connected to an instability of the transitional region.

-  For the transitional flows the magnitude and phase response to the prescribed motion differ significantly from the turbulent ones.

-  A similar resonance is found in wind tunnel data.

www.DLR.de • Chart 27 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 28: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 28

Future Work

-  Comparison to wind tunnel data from ongoing experiments with the CAST 10-2 airfoil at the DLR.

-  Validation of the transition model’s prediction capabilities for

unsteady transonic flows.

www.DLR.de • Chart 28 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 29: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 29

Flutter stability

Forced Response

Vibration due to flow instabilities

Aeroelasticity (relevant to fixed-wing aircraft)

Linear Frequency Domain Solver Laminar Flow, Shock Buffet Flutter Speed Flutter Analysis

1

2

4

3

Page 30: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 30

Shock Buffet

Jens Nitzsche STAB 2012

www.DLR.de • Chart 30 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 31: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 31

www.DLR.de • Chart 31 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 32: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 32

www.DLR.de • Chart 32 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 33: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 33

Shock Buffet -  NACA0010, Ma=0.69, Re=10×106, 2-d (U)RANS, SAO -  Pitch around c/4

𝜕𝑐↓𝑙 /𝜕𝛼 |↓𝛼=6° <0

www.DLR.de • Chart 33 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 34: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 34

Shock Buffet Aerodynamic Resonance

www.DLR.de • Chart 34 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 35: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 35

Shock Buffet Experiment in Transonic Windtunnel Göttingen (TWG):

www.DLR.de • Chart 35 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 36: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 36

Ma 0.80 Re 1.95×106

Page 37: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 37

Ma 0.80 Re 1.95×106

Page 38: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 38

Ma 0.80 Re 1.95×106

Page 39: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 39

Ma 0.80 Re 1.95×106

Page 40: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 40

Deduction

Shock buffet onset problem seems to be treatable as a linearized stability problem

www.DLR.de • Chart 40 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 41: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 41

Flutter stability

Forced Response

Vibration due to flow instabilities

Aeroelasticity (relevant to fixed-wing aircraft)

Linear Frequency Domain Solver Laminar Flow, Shock Buffet Flutter Speed Flutter Analysis

1

2

4

3

Page 42: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 42

Flutter Analysis

www.DLR.de • Chart 42 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 43: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 43

Challenges "  Applicability of validated CFD methods to a/c

design and aeroelastic certification process

"  Analyze aeroelastic stability in full operational and flight domain

"  High number of flight conditions, load cases, modes, reduced frequencies, …

"  Generalized airloads calculation as fast as by DLM

"  Identify critical couplings & conditions

Fast and Reliable Flutter Analysis

by frequency domain methods

www.DLR.de • Chart 43 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 44: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 44

Fast and Reliable Flutter Analysis

"  Simulations in time-domain to identify influence of nonlinearities at selected flight conditions "  from structure, or controls laws "  from aerodynamics

by frequency domain methods

www.DLR.de • Chart 44 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 45: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 45

Fast and Reliable Flutter Analysis for Complete Aircraft

Strategies 1.  Reduction of CPU time for CFD runs

"  Massive parallelization of process running nonlinear CFD "  Time-linearized RANS "  Reduced order modelling (ROM)

"  DLM correction methods 2.  Efficient approximation methods models to investigate structure and

system nonlinearities in time-domain 3.  Uncertainty analysis methods 4.  Combination of strategies 1 to 3

www.DLR.de • Chart 45 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013

Page 46: Holger Hennings, DLR – Inst. of Aeroelasticity · Holger Hennings, DLR – Inst. of Aeroelasticity MUSAF II COLLOQUIUM - AROUND AIRCRAFT & WITHIN ENGINES 18-20 SEPTEMBER 2013, TOULOUSE,

Chart 46

Conclusion

Linear Frequency Domain Solver validated for attached case

Laminar Flow, Flutter Speed

transonic dip deeper and at a lower Mach Shock Buffet

treatable as a linearized stability problem Flutter Analysis

reduction of CPU time

www.DLR.de • Chart 46 > Numerical Aeroelastic Simulation > Holger Hennings > MUSAF II 2013 > 18.09.2013