Transcript Atmospheric Remote Sensing - CCAR | CU

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
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
completed work
Yr
ongoing work
Milestones
Deliverables
1
Simulations of simple 3-D geometries with
candidate GSI models.
DSMC/GSI with atmosphere model
2
Down-select/calibrate GSI models w/
satellite data
DSMC/GSI w/ calibrated GSI options
3
DSMC computation of transition-regime
aerodynamic coefficients
Code to compute CD in slip/
transition flows for range of
geometries
4
Create database of altitude-dependent CD for Integrated simulation environment
representative satellites in transition flow.
code to produce CD database
5
Complete DSMC/GSI code for trajectory
simulations w/ direct modeling of flow
environment
10/28/2010
Integrated simulation environment
code to simulate real-time
application
M. D. Pilinski, C. Turansky, B. M. Argrow
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Background: The Accommodation Coefficient
Accommodation Coefficient
a) α=1.00
b) α=0.80
c) Pilinski et al. 2010
[Doornbos. 2011]
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Available Data: Fitted-Ballistic Measurements
Rocket Body Orbits
18:30:00, Jan 22, 1997
Data from 68 objects was
provided by Bruce Bowman at
AFSPC/A9A. Data spans 105 km
to 520 km altitudes from 1969 to
2004.
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Available Data: Tri-Axial Accelerometers
β
Y
φ
β
X
towards Earth
Z
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SESAM Parameter Inversion
Fitted-Ballistic Coefficients
10/28/2010
Bobs , t
BPhysMod , t
M. D. Pilinski, C. Turansky, B. M. Argrow

obs, t
AtmosMod ,
t
6
Results: SESAM model comparisons
fuel margin:
-0.05% to 0.05%
fuel margin:
-3% to 0%
fuel margin:
-0.05% to 5.0%
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Results: Comparison with Paddlewheel Measurements
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CHAMP-GUVI Comparisons
α = 0.78 (+0.10, -0.13)
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Tri-Axial Accelerometer Analysis
α = 0.89 (+0.02, -0.03)
Diffuse model with incomplete accommodation
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Result Summary
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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)
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Rigid-body dynamics
(modeling/approximation)
M. D. Pilinski, C. Turansky, B. M. Argrow
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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
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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
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Rigid-Body Dynamics
Equations of Motion: 2D
𝑢
𝑤
𝒔(𝑡) =
𝑞
𝜃
𝑡
𝑡
𝑡
𝑡
Source functions:
𝑋(𝑢, 𝑤, 𝑞, 𝑡)
𝑍(𝑢, 𝑤, 𝑞, 𝑡)
𝑀(𝑢, 𝑤, 𝑞, 𝑡)
𝑋(𝑢, 𝑤, 𝑞, 𝑡)
𝑚
𝑍(𝑢, 𝑤, 𝑞, 𝑡)
𝑞𝑢
+
𝒔=
𝑚
𝑀(𝑢, 𝑤, 𝑞, 𝑡)
𝐼𝑦𝑦
𝑞
q
𝑞𝑤 +
x
𝛼
𝑽∞
z
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?
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Aircraft-like Dynamics Results
NACA0012 in FM, Hypersonic flow: In-loop vs Sliding Taylor dynamic motion
𝛼0 = 15°
𝛼0 = 44°
Ma=10, Kn=100, Argon 1000K
unstable
trajectories
limit
cycles
separatrices
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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
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Thank You
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