OpenVSP with AVL
Transcript of OpenVSP with AVL
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Aeronautical Sciences Project
OpenVSP with AVL
Erik D. Olson NASA-Langley Research Center
OpenVSP Workshop v3 Aug. 22, 2014
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Outline
• NASA EET AR12 Model
• Flap Modeling
• OpenVSP to AVL Conversion
• Validation Results
• Degenerate Geometry
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NASA EET AR12 Model
Morgan, H.L. and Paulson, J.W.: NASA TP-1580 (1979) L-78-1654
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NASA EET AR12 Model
• Langley 14x22 Wind Tunnel ca. 1978
• 12-foot span supercritical wing
• Full-span slats
• Part-span double-slotted flaps with cutout
• Moveable horizontal tail
• Flow-through nacelles, landing gear
• Morgan, H. L.: NASA TM-80048 (1979) and Morgan, H.L. and Paulson, J.W.: NASA TP-1580 (1979)
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EET AR12 OpenVSP Model
• Planform shape from configuration description
• Wing airfoils from tabulated coordinates
• Fuselage sections digitized from plotted cross sections
• No nacelles, gear or gear pod
• Wing twist added to Hermite export file using external utility
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Flap and Control Surface Layout
Constant-chord double-slotted flap (30% chord at e=0.383)
30% chord double-slotted flap
15.5% chord slat
15.5% chord slat
h = 0.096
h = 0.97 h = 0.97
h = 0.97 h = 0.71
h = 0.45
h = 0.383
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Modeling of Flap Effects
• In practice, the theoretical lift increment from linear theory cannot be realized
– inadequacy of linear theory at large flap angles
– viscous effects
– flow separation at large flap angles
• Apply a flap effectiveness factor, 𝜂𝛿
• Account for slotted flap chord extension
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Slotted Flap Effectiveness
Single-slotted Double- and triple-slotted
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Empirical Chord Extension Ratios
0
0.2
0.4
0.6
0.8
1
1.2
0 10 20 30 40 50 60
Dc
/ c f
Flap deflection, deg
single-slotted
double-slotted w/ fixed vane
double-slotted (variable geom)
Fowler, single-slotted, double-slotted w/ fixed vaneFowler, double- and triple-slotted
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Athena Vortex Lattice (AVL)
• Open-source (GPL) code developed at MIT (Drela & Youngren)
• Forces and moments, trim, steady rotation
• Stability derivatives w.r.t. angles, rotation, control surfaces
• Rigib-body, quasi-steady eigenmode analysis
• Incidence, camber, and control-surface or flap deflections modeled as normal-vector tilt only
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OpenVSP to AVL Conversion
• Uses OpenVSP Hermite (Xsec) file export with external HRM2AVL utility
• AVL lifting surface sections (leading-edge coordinate, chord, incidence) calculated from Hermite cross sections
• Lifting-surface sections converted to normalized airfoils camberline determined by AVL
• Cruciform fuselage interpolated from Hermite cross sections
• Flap chord extension built into model
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Cruise Wing
Takeoff Flaps
EET AR12 AVL Model
Uncambered wing carry-through
Segmented panels with local cosine spacing
Cruciform fuselage
Flap chord extension
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0.00.20.40.60.81.01.21.41.61.82.02.22.42.62.83.0
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
CL
CD
AVL (ideal)AVL + DATCOMAVL + XfoilData
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
0.0
0.2
-4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24
Cm
angle of attack, deg
AVL (ideal)AVL + DATCOMAVL + XFoilData
Cruise Wing Validation Results
Mach 0.168, Rec = 1.37x106
0.00.20.40.60.81.01.21.41.61.82.02.22.42.62.83.0
-4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24
CL
angle of attack, deg
AVL (ideal)AVL + DATCOMAVL + XFoilData
XFoil CL,max = 1.79
• Actual 𝐶𝐿,max = 1.34
• Predicted 𝐶𝐿,max (XFoil) = 1.79 (+33%)
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Takeoff Wing Validation Results
0.00.20.40.60.81.01.21.41.61.82.02.22.42.62.83.0
-4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24
CL
angle of attack, deg
AVL (ideal)
AVL + DATCOM
Data
Cruise Wing Data
0.00.20.40.60.81.01.21.41.61.82.02.22.42.62.83.0
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
CL
CD
AVL (ideal)
AVL + DATCOM
Data
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
0.0
0.2
-4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24
Cm
angle of attack, deg
AVL (ideal)
AVL + DATCOM
Data
Mach 0.168, Rec = 1.37x106
• Actual 𝐶𝐿,max = 2.51
• Predicted 𝐶𝐿,max (Xfoil + empirical Dcl,max) = 2.41 (-4.0%)
XFoil CL,max = 2.41
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Landing Wing Validation Results
Mach 0.168, Rec = 1.37x106
0.00.20.40.60.81.01.21.41.61.82.02.22.42.62.83.0
-4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24
CL
angle of attack, deg
AVL (ideal)
AVL + DATCOM
Data
Cruise Wing Data
0.00.20.40.60.81.01.21.41.61.82.02.22.42.62.83.0
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
CL
CD
AVL (ideal)
AVL + DATCOM
Data
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
0.0
0.2
-4 -2 0 2 4 6 8 10 12 14 16 18 20 22 24
Cm
angle of attack, deg
AVL (ideal)
AVL + DATCOM
Data
• Actual 𝐶𝐿,max = 2.82
• Predicted 𝐶𝐿,max (Xfoil + empirical Dcl,max) = 2.77 (-1.8%)
XFoil CL,max = 2.77
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OpenVSP v3.0 Degenerate Geometry
OpenVSP Model Plate Export