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Marcin Pilinski, Craig Turansky , Brian Argrow University of Colorado, Boulder

Research Progress Satellite Drag in Free-Molecular and Transition Flow Focus Area VIII October 26, 2011. Marcin Pilinski, Craig Turansky , Brian Argrow University of Colorado, Boulder. Thanks to Scott Palo, Bruce Bowman, Ken Moe and Mildred Moe, Eric Sutton, and Eelco Doornbos.

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Marcin Pilinski, Craig Turansky , Brian Argrow University of Colorado, Boulder

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  1. Research ProgressSatellite Drag in Free-Molecularand Transition FlowFocus Area VIIIOctober 26, 2011 Marcin Pilinski, Craig Turansky, Brian Argrow University of Colorado, Boulder Thanks to Scott Palo, Bruce Bowman, Ken Moe and Mildred Moe, Eric Sutton, and EelcoDoornbos

  2. Focus Area VIII: Satellite Drag in the Re-Entry Region Objective: To significantly advance understanding of satellite drag in the transition and near-continuum regimes using state-of-the art numerical modeling, and to provide CD predictions under a broadened range of conditions M. D. Pilinski, C. Turansky, B. M. Argrow

  3. Background: The Accommodation Coefficient • Accommodation Coefficient • α=1.00 • α=0.80 • Pilinski et al. 2010 [Doornbos. 2011] M. D. Pilinski, C. Turansky, B. M. Argrow

  4. Available Data: Fitted-Ballistic Measurements Data from 68 objects was provided by Bruce Bowman at AFSPC/A9A. Data spans 105 km to 520 km altitudes from 1969 to 2004. M. D. Pilinski, C. Turansky, B. M. Argrow

  5. Available Data: Tri-Axial Accelerometers aligned with boom towards Earth M. D. Pilinski, C. Turansky, B. M. Argrow

  6. SESAM Parameter Inversion Fitted-Ballistic Coefficients M. D. Pilinski, C. Turansky, B. M. Argrow

  7. Results: SESAM model comparisons fuel margin: -0.05% to 0.05% fuel margin:-3% to 0% fuel margin:-0.05% to 5.0% M. D. Pilinski, C. Turansky, B. M. Argrow

  8. Results: Comparison with Paddlewheel Measurements M. D. Pilinski, C. Turansky, B. M. Argrow

  9. CHAMP-GUVI Comparisons α = 0.78 (+0.10, -0.13) M. D. Pilinski, C. Turansky, B. M. Argrow

  10. Tri-Axial Accelerometer Analysis Diffuse model with incomplete accommodation α = 0.89 (+0.02, -0.03) M. D. Pilinski, C. Turansky, B. M. Argrow

  11. Result Summary M. D. Pilinski, C. Turansky, B. M. Argrow

  12. Spacecraft Simulation Goals • Redefine the problem from satellite drag to spacecraft fluid dynamics Treat spacecraft dynamics more like aircraft dynamics where possible Full dynamic simulation (beyond drag) Numerical Simulations (e.g. DSMC) Rigid-body dynamics (modeling/approximation) M. D. Pilinski, C. Turansky, B. M. Argrow

  13. DSMC Development Bird’s “production” codes DS2V, DS3V Current, best available option for DSMC • The Good • Free, download at gab.com.au • Highly reliable • Verified by many people • Chemical reactions/internal • modes present • The Bad • Limited geometry, BCs • Requires a free-stream • Difficult batch processing • Only 2 GSI models • Maxwellian diffuse • Pure specular • Closed source • Can’t fix/extend it DS2V User Interface M. D. Pilinski, C. Turansky, B. M. Argrow

  14. DSMC Development • DSMC is a tool for rarefied/transition gas flows that we need • Current DSMC tools are “dull” (insufficient and/or unavailable) • New code: Voldipar created to act as a sharper tool • Current state of Voldipar verified with • benchmark problems • Supersonic Flat Plate • Hypersonic Cylinder • NACA0012 M. D. Pilinski, C. Turansky, B. M. Argrow

  15. Rigid-Body Dynamics Equations of Motion: 2D q x z Source functions: Gas forces from some model or simulation • Take an example: • Panel method in Free-Molecular (FM) flow to get X,Z,M • What happens to an airfoil at Ma=10, Kn=100? M. D. Pilinski, C. Turansky, B. M. Argrow

  16. Aircraft-like Dynamics Results NACA0012 in FM, Hypersonic flow: In-loop vs Sliding Taylor dynamic motion Ma=10, Kn=100, Argon 1000K unstable trajectories limit cycles separatrices M. D. Pilinski, C. Turansky, B. M. Argrow

  17. Conclusions • Seeking to better understand spacecraft motion beyond drag • Want to make spacecraft as familiar as aircraft • Developing better numerical tools – DSMC (Voldipar code) • Starting to investigate how to apply this to rigid-body dynamics • Examples in 2D show this is possible Future • Add more to Voldipar code (GSI, 3D upgrade, better BCs, generalized) • Examine new methods for approximation of dynamics • Look into possible LBM-DSMC coupling for transition region Eventual Goal Provide “single file”, full-dynamic description of spacecraft motion due to rarefied/transition flow M. D. Pilinski, C. Turansky, B. M. Argrow

  18. Thank You M. D. Pilinski, C. Turansky, B. M. Argrow

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