NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
VSPAERO
Verification Testing
Presented by:Lucas Payne
Empirical Systems Aerospace, Inc.
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
Agenda
• Introduction• Approach
– Previous Studies/References• Test Cases Overview• Test Case
– Methodology• Geometry setup• Test Setup
– Results• Errors
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
Problem Statement
• VSPAERO is a relatively new solver with few authoritative verification studies
• VSPAEROs rapid feature development and capabilities are not supported with verification artifacts
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
Introduction
• Objective:– Verify VSPAERO results with comparisons to
authoritative theoretical and empirical solutions– ID bugs in UI/solver– Develop verification toolset– Document best analysis practices
• Requirements:– Ability to automate– Immediate plotting of results– Control of features that impact solution quality & speed
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
Approach
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
Other Studies/References
• VLM manual for Surfaces – Used similar testing cases
• Hershey-Bar Wing• Swept Wing• Warren-12
• Dave Kinney, Workshop 16’– High AR Wing– Supersonic Delta Wing
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
Test Rational
Completed:
Hershey-Bar Wing Easy to re-create in OpenVSPEmpirical solutions available
Swept Wing & Bertin-Smith Wing Easy to re-create in OpenVSPEmpirical solutions available
Warren-12 Wing Easy to re-create in OpenVSPEmpirical solutions available
Von Karman-Trefftz Airfoil Easy to re-create in OpenVSPExact 2D solution available
Testing CP slicer
Planned:
Ellipsoid Easy to re-create in OpenVSPExact solutions available
Cessna 172Empirical solutions available
Test Case Overview
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
Hershey-bar Wing: Methodology
• Method: VLM• Compare to:
– 2D Theory (2p)– Lifting Line Theory
𝜕𝛼𝜕𝐶$
≈ 10 +9𝐴𝑅, +
20𝐴𝑅
Parameter Min Max N-PtsAR 5 60 12
N-Span 6 100 5N-Chord 20 110 5
Tip Cluster 0.1 1 3
Test Matrix: 900 Unique variations
Default Clustering: LE = 0.25, TE = 0.25, Root = 1
Hoerner (1992)
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
Hershey-bar Wing: Results
Ave % Diff of VSP to LLT: -2.2 %
% Diff of AR60 to thin Approx (2p): -8.9 %
Run from: OpenVSP v3.13.1VSPAERO v4.1.1
Default Clustering: LE = 0.25, TE = 0.25, Root = 1, Tip = 1Default Tessellation: N-Chord = 33, N-Span = 6
Run conditions: AOA = -20, -15, -10, -5, 0, 5, 10, 15, 20°
M = 0.1
% Dif = 100*(est-truth)/truthest = CLa(VSP)truth = CLa(Calculated from LLT)
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
Hershey-bar Wing: Results – Grid Study
Clustering: LE = 0.25, TE = 0.25, Root = 1, Tip = 0.2
% Dif = 100*(est-truth)/truthest = CLa(VSP)truth = CLa(Calculated from LLT)
Run from: OpenVSP v3.13.1VSPAERO v4.1.1
Run conditions: AOA = 1°M = 0.1
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
Hershey-bar Wing: Results – Grid Study
𝐴𝑅.. =
0.5 ∗ 𝐴𝑅𝑆𝑝𝑎𝑛𝑇𝑒𝑠𝑠 − 1
𝑐𝐶ℎ𝑜𝑟𝑑𝑇𝑒𝑠𝑠 − 1
2 Run from: OpenVSP v3.13.1VSPAERO v4.1.1
Run conditions: AOA = 1°M = 0.1
Clustering: LE = 0.25, TE = 0.25, Root = 1, Tip = 1
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
• Method: VLM• Compare to:
– 3D theoretical
Parameter Min Max N-PtsAR 5 60 12
N-Span 6 100 5N-Chord 20 110 5
Tip Cluster 0.1 1 3
Test Matrix: 900 Unique variations
Swept Wing: Methodology
𝐶$@ =2𝜋 ∗ 𝐴𝑅
2 + 𝐴𝑅,𝛽,k, 1 +
tan, LF/,𝛽, + 4
�
AR = Aspect Ratioβ = Mach parameter = 1 −𝑀,� , M = 0.1k= Ratio of 2D CLa to 3D CLa, 1 for theoreticalLF/,= Sweep at 50% chord
Default Clustering: LE = 0.25, TE = 0.25, Root = 1
Lowry and Polhamus (1957)
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
Swept Wing: Results
% Dif: +3.8%
*Tessellations: N-Chord = 80, N-Span = 6;
Run from: OpenVSP v3.13.1VSPAERO v4.1.1
Run conditions: AOA = 1°M = 0.1
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
Swept Wing: Methodology – Case 2
Parameter Min Max N-PtsAR 5 60 12
Sweep 5 40 8
Test Matrix: 96 Unique variations
*Same Clustering: LE = 0.35, TE = 0.65Default Root/Tip Clustering = 1
Goal: Test how sweep changes accuracy of solution
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
Swept Wing: Results
*Tessellation: N-chord = 80, N-span = 6
*Tessellation: N-chord = 60, N-span = 20
Run from: OpenVSP v3.13.1VSPAERO v4.1.1
Run conditions: AOA = 1°M = 0.1
*Same Clustering: LE = 0.35, TE = 0.65Default Root/Tip Clustering = 1
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
Bertin-Smith Wing: Methodology
• Published data• VLM• Comparisons made
between CLa.– Tessellations:
N-Chord = 61 N-Span = 7
Great OWL Publishing (2009)
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
Bertin-Smith Wing: Results
• Published results are: CLa = 3.433 /rad
• VSPAERO Results: CLa = 3.204 /rad» % Diff: -6.7%
Run from: OpenVSP v3.13.1VSPAERO v4.1.1
Run conditions: AOA = 1°M = 0.1
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
• Published data• VLM• Comparisons made
between CLa and CMa
– Tessellations:N-Chord = 61 N-Span = 7
Warren-12 Wing: Methodology
Great OWL Publishing (2009)
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
19
Empirical Systems Aerospace, Inc. www.esaero.com
Warren-12 Wing: Results
• Published results:
– CLa = 2.743 /rad
– CMa = -3.10 /rad
• VSPAERO Results:
– CLa = 2.7473 /rad• % Diff: +0.16%
– CMa = -3.1495 /rad• % Diff: +1.6%
Run from: OpenVSP v3.13.1VSPAERO v4.1.1
Run conditions: AOA = 1°M = 0.1
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
20
Empirical Systems Aerospace, Inc. www.esaero.com
Von Karman-Trefftz Wing: Methodology
• Method: Panel• Compare to:
– Karman-Trefftz Transformation Solution– CP slicer
Parameter Min Max N-PtsEpsilon 0.1 0.2 3Kappa 0 0.2 5
Tau 5 20 4
Test Matrix: 60 Unique variations
Same AR = 30Same tessellation: N-chord = 70, N-span = 30Same Clustering: LE = 0.35, TE = 0.65, Root/Tip = 1
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
21
Empirical Systems Aerospace, Inc. www.esaero.com
Von Karman-Trefftz Wing: ResultsRun from: OpenVSP v3.13.1
VSPAERO v4.1.1
Run conditions: AOA = 0°M = 0.1
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
Von Karman-Trefftz Wing: ResultsRun from: OpenVSP v3.13.1
VSPAERO v4.1.1
Run conditions: AOA = 0°M = 0.1
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
Von Karman-Trefftz: Methodology
Parameter Min Max N-PtsKappa 0 0.1 2N-Span 15 80 5N-Chord 15 80 5
Test Matrix: 50 Unique variations
*Same AR = 15Same Airfoil parameters: Epsilon = 0.1, Tau = 15Same Clustering: LE = 0.5, TE = 1.0, Root/Tip = 1
Goal: Test how tessellations impact CP slicer and the accuracy of solution
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
Von Karman-Trefftz Wing: Results
*Same AR = 15Same Airfoil parameters: Epsilon = 0.1, Tau = 15Same Clustering: LE = 0.5, TE = 1.0, Root/Tip = 1
Run from: OpenVSP v3.13.1VSPAERO v4.1.1
Run conditions: AOA = 0°M = 0.1
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
25
Empirical Systems Aerospace, Inc. www.esaero.com
Von Karman-Trefftz Wing: Results
*Same AR = 15Same Airfoil parameters: Epsilon = 0.1, Tau = 15Same Clustering: LE = 0.5, TE = 1.0, Root/Tip = 1
Run from: OpenVSP v3.13.1VSPAERO v4.1.1
Run conditions: AOA = 0°M = 0.1
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
26
Empirical Systems Aerospace, Inc. www.esaero.com
Karman-Trefftz Wing: Error Example
• Symptom: Erratic CP distribution at outer span• Cause: User error - Half mesh generation due to X-Z Symmetry• Status: Improvements made to make repeating this mistake more difficult
Before: After:
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
• Tool suite Features– Improved Automation– Add all plots/results to wiki– Add Scripts to future releases
• Next Tests– Ellipsoid– Cessna 172
Ongoing Work
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
1. Great OWL Publishing. (2009) Surfaces Vortex Lattice Module: User Manual
2. Hoerner, Sighard F., and Henry V. Borst. Fluid-dynamic Lift: Practical Information on Aerodynamic and Hydrodynamic Lift. N.p.: Hoerner, 1992. N. pag. 3-2. Print.
3. Lowry, John G., and Edward C. Polhamus. "A Method for Predicting Lift Increments Due to Flap Deflection at Low Angles of Attack in Incompressible Flow." NACA-TN-3911 (1957): 1-30. NASA Technical Reports Server. Web.
References:
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
Questions?
NNX09CC86P SBIR Review, Presented to NASA, July 7th, 2009OpenVSP Workshop 2017 Aug. 30th – Sep. 1st
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Empirical Systems Aerospace, Inc. www.esaero.com
Contact Information
Lucas [email protected]
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