Transcript eN Transition Prediction for 3D Wing Configurations using Database Methods and a local, linear Stability Code Andreas Krumbein German Aerospace Center Institute of Aerodynamics and.

eN Transition Prediction for 3D Wing Configurations
using Database Methods and a local, linear Stability
Code
Andreas Krumbein
German Aerospace Center
Institute of Aerodynamics and Flow Technology, Numerical Methods
7th ONERA-DLR Aerospace Symposium - ODAS 2006, ONERA, Centre de Toulouse, Folie 1
Andreas Krumbein > 6 October 2006
Outline
Outline
Introduction
Transition Prediction Coupling Structure
Test Case: ONERA M6 wing
Computational Results
Conclusion
Outlook
7th ONERA-DLR Aerospace Symposium - ODAS 2006, ONERA, Centre de Toulouse, Folie 2
Andreas Krumbein > 6 October 2006
Introduction
Introduction
Aircraft industry requirements:
RANS based CFD tool with transition prediction
Automatic, no intervention of the user
Reduction of modeling based uncertainties
Accuracy of results from fully turbulent flow or flow with
prescribed transition often not satisfactory
Improved simulation of the interaction between transition locations
and separation
7th ONERA-DLR Aerospace Symposium - ODAS 2006, ONERA, Centre de Toulouse, Folie 3
Andreas Krumbein > 6 October 2006
Introduction
Different approaches:
RANS solver + stability code + eN method
RANS solver + boundary layer code
+ stability code + eN method
RANS solver + boundary layer code
+ eN database method(s)
RANS solver + transition closure model or
transition/turbulence model
7th ONERA-DLR Aerospace Symposium - ODAS 2006, ONERA, Centre de Toulouse, Folie 4
Andreas Krumbein > 6 October 2006
Introduction
Different approaches:
RANS solver + stability code + eN method
RANS solver + boundary layer code
+ stability code + eN method
RANS solver + boundary layer code
+ eN database method(s)
RANS solver + transition closure model or
transition/turbulence model
7th ONERA-DLR Aerospace Symposium - ODAS 2006, ONERA, Centre de Toulouse, Folie 5
Andreas Krumbein > 6 October 2006
Introduction
Different approaches:
RANS solver + stability code + eN method
RANS solver + boundary layer code
+ stability code + eN method
RANS solver + boundary layer code
+ fully automated stability code
+ eN method
RANS solver + boundary layer code
+ eN database method(s)
RANS solver + transition closure model or
transition/turbulence model
7th ONERA-DLR Aerospace Symposium - ODAS 2006, ONERA, Centre de Toulouse, Folie 6
Andreas Krumbein > 6 October 2006
Coupling Structure
Transition Prediction Coupling Structure
cycle = kcyc
7th ONERA-DLR Aerospace Symposium - ODAS 2006, ONERA, Centre de Toulouse, Folie 7
Andreas Krumbein > 6 October 2006
Coupling Structure
Transition Prediction Module:
Laminar boundary-layer method for swept, tapered wings
(conical flow)
1.) eN database-methods for TS (Stock) and CF (Casalis/Arnal) instabilities
2.) local, linear stability code LILO (Schrauf)
Laminar separation approximates transition if transition downstream
of laminar separation point
2d, 2.5d (infinite swept) + 3d wings
Single + multi-element configurations
N factor integration along chordwise gridlines
Attachment line transition, by-pass transition & transition inside
laminar separation bubbles not yet covered
7th ONERA-DLR Aerospace Symposium - ODAS 2006, ONERA, Centre de Toulouse, Folie 8
Andreas Krumbein > 6 October 2006
Coupling Structure
Structured RANS solver FLOWer:
3D RANS, compressible, steady/unsteady
Structured body-fitted multi-block meshes
Finite volume formulation
Cell-vertex and cell-centered spatial discretizations schemes
Central differencing, 2nd & 4th order artificial dissipation scaled by
largest eigenvalue
Explicit Runge-Kutta time integration
Steady: local time stepping & implicit residual smoothing, embedded
in a multi-grid algorithm
eddy viscosity TMs (Boussinesq) & alg./diff. RSMs
7th ONERA-DLR Aerospace Symposium - ODAS 2006, ONERA, Centre de Toulouse, Folie 9
Andreas Krumbein > 6 October 2006
Coupling Structure
Transition Prescription:
PTupp(sec = 1)
Automatic partitioning into
laminar and turbulent zones
individually for each element
PTupp(sec = 2)
PTupp(sec = 3)
PTupp(sec = 4)
Laminar points: St,p  0 or me = 0
Independent of topology
7th ONERA-DLR Aerospace Symposium - ODAS 2006, ONERA, Centre de Toulouse, Folie 10
Andreas Krumbein > 6 October 2006
Coupling Structure
Algorithm:
set stru and strl far downstream
compute flowfield
check for RANS laminar separation  set separation points as new stru,l
cl  const. in cycles
 call transition module
 use outcome of eN-databases/LILO or
BL laminar separation point as new transition point
set new stru,l underrelaxed  stru,l = stru,l d,
1.0 < d < 1.5
convergence check  Dstru,l < e
no
yes
STOP
7th ONERA-DLR Aerospace Symposium - ODAS 2006, ONERA, Centre de Toulouse, Folie 11
Andreas Krumbein > 6 October 2006
Test Case
Test Case
M6 wing: single-element
semi-span: A = 3.8
swept:
LLE = 30°, LTE = 15.8°
tapered:
l = 0.562
Grid: 384,000 points (176 in section, 32 spanwise )
M = 0.262, Re = 3.5106, a = 0°, 5°, 10°, 15°
Tu = 0.2% (WT: S2Ch, Chalais-Meudon)
→ N = 6.485 using Mack’s relationship
transition detection in experiment: sublimation of naphtalene
turbulence model:
Baldwin-Lomax
critical N-factors:
NTScr = NCFcr = 6.485
transition prediction in 3 wing sections near h = 0.22, 0.42, 0.86
7th ONERA-DLR Aerospace Symposium - ODAS 2006, ONERA, Centre de Toulouse, Folie 12
Andreas Krumbein > 6 October 2006
Transition locations at h = 0.45 and maximum N factor curves for
TS and CF waves at h = 0.45 and a = 5.0°
Results
h = 0.45
CF
a = 5.0°
ls
7th ONERA-DLR Aerospace Symposium - ODAS 2006, ONERA, Centre de Toulouse, Folie 13
Andreas Krumbein > 6 October 2006
Results
Stability boundary
calibration of critical CF N factor
for lower side and a = 5.0° at
h = 0.42 → NCFcr = 5.157
Very probably the naphtalene
has accelerated transition!
7th ONERA-DLR Aerospace Symposium - ODAS 2006, ONERA, Centre de Toulouse, Folie 14
Andreas Krumbein > 6 October 2006
Results
 x sec



NTS(xsec) = max    a i (f ; xsec ) dxsec  TS in database and LILO
f  0

 x sec


 x sec

 x sec






NCF(xsec) = max    a i (f  0, l ; x sec ) dx sec 
NCF(xsec) = max  max    a i (f, ; xsec ) dxsec  
  f  0
l  0


 x sec


 x sec

CF in database: travelling
CF in LILO: stationary
7th ONERA-DLR Aerospace Symposium - ODAS 2006, ONERA, Centre de Toulouse, Folie 15
Andreas Krumbein > 6 October 2006
taken from *)
Transition lines for
11 wing sections
upper
side
Results
lower
side
h = 0.000, 0.110,
0.220, 0.325,
0.420, 0.800,
0.860, 0.900,
0.930, 0.960,
0.975
Calibration of both
critical N factors for
lower side and a = 5°:
NCFcr = 5.157 → h = 0.42
NTScr = 4.75 → h = 0.96
TS
upper
side
ls
ls
a = 0°
a = 0°
a = 5°
a = 5°
a = 15°
a = 15°
TS
TS
*)Schmitt, V., Cousteix, J., “Étude de la couche limite
tridimensionelle sur une aile en flèche,” ONERA Rapport
Technique N° 14/1713 AN, Châtillon, France, July 1975
lower
side
all ls
all ls
CF
all CF
7th ONERA-DLR Aerospace Symposium - ODAS 2006, ONERA, Centre de Toulouse, Folie 16
Andreas Krumbein > 6 October 2006
Conclusion/Outlook
Conclusion/Outlook
Transition information from experiments is often very limited so that
problems can arise when validation work is done
Usually no information in terms of the N factors is given; often Mack‘s
relationship is not sufficient; in the worst case the CF factor must be
guessed
In cases with enough experimental transition points the critical N factors
can/must be calibrated
Stability boundary must be known based on sufficient experimental data
at least 4 points in NcrCF-NcrTS–plane
for different integration strategies (advantageous)
transition points and cp in 7-8 sections over half-span on upper and lower side
criterion for transition downstream of laminar separation necessary
more validation cases, e.g. DLR F5 wing → transonic test case
3D high-lift multi-element configuration (European project EUROLIFT II)
using LILO + criteria for
- transition in laminar separation bubbles
- bypass transition
- attachment line transition
7th ONERA-DLR Aerospace Symposium - ODAS 2006, ONERA, Centre de Toulouse, Folie 17
Andreas Krumbein > 6 October 2006