Missile Configuration Test Cases by Peter Cross John Carter Ron Schultz 1
Purpose of Study • Evaluate the accuracy of the Star-CCM+ CFD package in predicting the aerodynamic coefficients of supersonic missile configurations – Longitudinal coefficients • Axial Force, Normal Force, Pitching Moment – Lateral coefficients • Side Force, Rolling Moment, Yawing Moment – Invest “reasonable” level of effort in generating meshes and setting up cases – Consider both conventional & unconventional missile configurations – Conduct study over large range of angles of attack – Include configurations with large control deflections 2
Missile Configurations Studied 3
Missile Configuration Overview • Tandem Control Missile – “Generic” missile design • Independent tail & canard control surfaces • Test data available for both “+ ” & “x” orientations – Simulation conditions • Mach: 2.5 • Alpha sweep: 0 - 28 in 2 increments • Control deflections: various combinations up to 20 – Experimental data • Tests conducted by A. B. Blair in Langley Unitary Plan Wind Tunnel in 1993 • Data is unpublished, obtained from Floyd Wilcox, NASA Langley • Referenced & used in AIAA 2002-0275 4
Star-CCM+ Case Setup • Initial “baseline” configuration – Import geometry – Select mesh & physics models • Used coupled flow solver • K-omega turbulence model with All y+ wall treatment – ~ 6+ surface mesh user iterations • Even more if using surface wrapper tool – ~ 3+ volume mesh user iterations – Set boundary / initial conditions – Set reports / monitors / plots / etc. • Control deflection configuration – Built upon baseline configuration – ~ 3 surface mesh user iterations – ~ 1 volume mesh user iteration 5
Star-CCM+ Meshing • Set up mesh on surfaces – Want refined mesh in areas of high curvature or detail • Nose, leading edge, fins, etc – Want larger cells in other areas to reduce cell count • Body, domain boundaries, etc – Want smooth growth rate in cell size • Set up “feature curves” – To preserve sharp edges or other important geometry features • Set up prism layer mesh to capture boundary layer – Wall cell thickness to give desired Y+ • All y+ 1 < y+ < 30 • Low y+ y+ < 0.4 (y+ < 5 recommended ) • High y+ 15 < y+ < 40 (30 < y+ < 100 recommended ) – Prism layer thickness, # of cell layers, stretch ratio • Volume mesh generated automatically by program – Can get large cells where small cells are desired & vice versa • Add “volume sources” to refine mesh in certain areas – Can get poor cells in interfaces between volume sources or between volume source and prism layer mesh 6
Mesh: Tandem Control Missile “+ ” 7
Mesh: Tandem Control Missile “x” 8
Star-CCM+ Run Metrics • Tandem control missile in “+ ” configuration – Half model – Approximately 1.5M cells – Meshing time • < 5 minutes surface mesh • ~ 30 minutes volume mesh – Solution time • ~ 3 hours per alpha (~ 600-700 iterations) • Full alpha sweep in < 48 hours • Tandem control missile in “x” configuration – Half model – Approximately 2.0M cells – Meshing time • < 5 minutes surface mesh • ~ 50 minutes volume mesh – Solution time • ~ 6 hours per alpha (~ 1200 iterations) • Full alpha sweep in < 72 hours 9
Computing Environments • “Boxcluster” (primary) – 4 nodes – 1 dual-core Intel Core 2 Duo E6850 processor @ 3.00 GHz per node – 8 GB memory per node – ~ 270 iterations per hour for 1.5M cells • “Falcon” (AFRL HPC Cluster) – Used for additional solving power – Used 6 nodes (out of 1024) – 2 single-core AMD Opteron processors @ 2.8 GHz per node – 4 GB memory per node – ~ 260 iterations per hour for 1.5M cells 10
Tandem Control Missile “+ ” Configuration Canard: 0 / Tail: 0 Canard: 0 / Tail: -20 Canard: 20 / Tail: 0 Canard: 20 / Tail: -20 Canard: 10 / Tail: 10 11
Flow Field: T.C.M “+ ”, α = 10 12
Flow Field: T.C.M “x”, α = 10 13
T.C.M. “+ ” Results: Axial Force 1.80 1.60 1.40 Run 47 Axial Force Coefficient Run 1003 1.20 Star-CCM+ 0/0 Run 1015 1.00 Star-CCM+ 0/-20 Run 1010 0.80 Star-CCM+ 20/0 Run 1046 Star-CCM+ 20/-20 0.60 Run 53 Star-CCM+ 10/10 0.40 0.20 0.00 -5 0 5 10 15 20 25 30 Angle of Attack, degrees 14
T.C.M. “+ ” Results: Normal Force 14.00 12.00 10.00 Run 47 Normal Force Coefficient Run 1003 8.00 Star-CCM+ 0/0 Run 1015 6.00 Star-CCM+ 0/-20 Run 1010 4.00 Star-CCM+ 20/0 Run 1046 Star-CCM+ 20/-20 2.00 Run 53 Star-CCM+ 10/10 0.00 -2.00 -4.00 -5 0 5 10 15 20 25 30 Angle of Attack, degrees 15
Tandem Control Missile “+ ” Configuration 20.00 15.00 Pitching Moment Coefficient Run 47 Run 1003 10.00 Star-CCM+ 0/0 Run 1015 Star-CCM+ 0/-20 5.00 Run 1010 Star-CCM+ 20/0 Run 1046 Star-CCM+ 20/-20 0.00 Run 53 Star-CCM+ 10/10 -5.00 -10.00 -5 0 5 10 15 20 25 30 Angle of Attack, degrees 16
Tandem Control Missile “x” Configuration Canard: 0 / Tail: 0 Canard: 20 / Tail: 0 Canard: 0 / Tail: -20 Canard: 10 / Tail: -10 Canard: 20 / Tail: 20 17
T.C.M. “x” Results: Axial Force 4.50 4.00 3.50 Run 1004 Axial Force Coefficient Star-CCM+ 0/0 3.00 Run 1044 Star-CCM+ 0/-20 2.50 Run 1037 Star-CCM+ 20/0 2.00 Run 1020 Star-CCM+ 10/-10 1.50 Run 1039 Star-CCM+ 20/20 1.00 0.50 0.00 -5 0 5 10 15 20 25 30 Angle of Attack, degrees 18
T.C.M. “x” Results: Normal Force 16.00 14.00 12.00 Normal Force Coefficient Run 1004 10.00 Star-CCM+ 0/0 Run 1044 8.00 Star-CCM+ 0/-20 Run 1037 6.00 Star-CCM+ 20/0 Run 1020 4.00 Star-CCM+ 10/-10 Run 1039 2.00 Star-CCM+ 20/20 0.00 -2.00 -4.00 -5 0 5 10 15 20 25 30 Angle of Attack, degrees 19
T.C.M. “x” Results: Pitching Moment 20.00 15.00 Pitching Moment Coefficient Run 1004 10.00 Star-CCM+ 0/0 Run 1044 Star-CCM+ 0/-20 5.00 Run 1037 Star-CCM+ 20/0 0.00 Run 1020 Star-CCM+ 10/-10 Run 1039 -5.00 Star-CCM+ 20/20 -10.00 -15.00 -5 0 5 10 15 20 25 30 Angle of Attack, degrees 20
Elliptic Missile 21
Missile Configuration Overview • Elliptic Missile – Unconventional missile concept • Body has elliptical cross section • Mono-wing design • Tail surfaces in “x” configuration with 30 dihedral – Simulation conditions • Mach: 2.5 • Alpha sweep: 0 - 28 in 2 increments • Beta sweeps: 0 - 10 in 2 increments – at alpha 0 & 10 • Control deflections: none – Experimental Data • NASA Technical Memorandum 74079, 1977 • NASA Technical Memorandum 80055, 1979 22
Mesh: Elliptic Missile (Original) Cut plane through mesh 23
Elliptic Missile Original Mesh (3.7M Cells) Inadequate mesh refinement in this region Obtain excessive mesh refinement in this region 24
Meshing Issues: Elliptic Missile Symmetry plane (cell size controlled by surface mesh). Mesh grows more quickly than desired away from surfaces. Cut plane through mesh (automatic cell size) 25
Elliptic Missile Original Mesh (3.7M Cells) 26
Elliptic Missile Improved Mesh (3.8M Cells) Volume sources placed around fins. Placed “Interface” surface around missile to slow mesh growth rate near missile body. 27
Mesh: Elliptic Missile (Improved) Cut plane through mesh 28
Mesh: Elliptic Missile (Original) Cut plane through mesh 29
Flow Field: Elliptic Missile, α = 10 β = 0 30
Flow Field: Elliptic Missile, α = 0 β = 10 31
Elliptic Missile Results: Axial Force 0.30 0.25 Axial Force Coefficient 0.20 Experiment 0.15 Star-CCM+ Remesh 0.10 0.05 0.00 -5 0 5 10 15 20 25 30 35 Angle of Attack, degrees 32
Elliptic Missile Results: Normal Force 12.00 10.00 Normal Force Coefficient 8.00 6.00 Experiment Star-CCM+ Remesh 4.00 2.00 0.00 -2.00 -5 0 5 10 15 20 25 30 35 Angle of Attack, degrees 33
Elliptic Missile Results: Pitching Moment 0.30 0.20 0.10 Pitching Moment Coefficient 0.00 Experiment -0.10 Star-CCM+ Remesh -0.20 Adjusted If WTT reference center is -0.30 shifted 0.16” aft of reported location, Star-CCM+ results -0.40 match experimental data well. -0.50 -0.60 -5 0 5 10 15 20 25 30 35 Angle of Attack, degrees 34
Elliptic Missile Results: Rolling Moment 0.20 0.10 Rolling Moment Coefficient 0.00 -0.10 Experiment, Alpha = 0 Star-CCM+, Alpha = 0 -0.20 Remesh, Alpha = 0 Experiment, Alpha = 10 Star-CCM+, Alpha = 10 -0.30 -0.40 -0.50 -0.60 -6 -4 -2 0 2 4 6 8 10 12 Sideslip Angle, degrees 35
Elliptic Missile Results: Side Force 0.10 0.00 -0.10 Side Force Coefficient -0.20 Experiment, Alpha = 0 Star-CCM+, Alpha = 0 -0.30 Remesh, Alpha = 0 Experiment, Alpha = 10 Star-CCM+, Alpha = 10 -0.40 -0.50 -0.60 -0.70 -6 -4 -2 0 2 4 6 8 10 12 Sideslip Angle, degrees 36
Elliptic Missile Results: Yawing Moment 0.30 0.20 0.10 Yawing Moment Coefficient 0.00 Experiment, Alpha = 0 -0.10 Star-CCM+, Alpha = 0 Remesh, Alpha = 0 -0.20 Experiment, Alpha = 10 Star-CCM+, Alpha = 10 -0.30 -0.40 -0.50 -0.60 -6 -4 -2 0 2 4 6 8 10 12 Sideslip Angle, degrees 37
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