Research Progress Satellite Drag in Free-Molecular and Transition Flow Focus Area VIII October 26, 2011 Marcin Pilinski, Craig Turansky, Brian Argrow University

Research Progress

Satellite Drag in Free-Molecularand Transition Flow

Focus Area VIIIOctober 26, 2011

Marcin Pilinski, Craig Turansky, Brian ArgrowUniversity of Colorado, Boulder

Thanks to Scott Palo, Bruce Bowman, Ken Moe and Mildred Moe, Eric Sutton, and Eelco Doornbos

M. D. Pilinski, C. Turansky, B. M. Argrow 2

Focus Area VIII: Satellite Drag in the Re-Entry Region

10/28/2010

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

Yr 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 representative satellites in transition flow.

Integrated simulation environment code to produce CD database

5 Complete DSMC/GSI code for trajectory simulations w/ direct modeling of flow environment

Integrated simulation environment code to simulate real-time application

completed work ongoing work

Background: The Accommodation Coefficient

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[Doornbos. 2011]

M. D. Pilinski, C. Turansky, B. M. Argrow

Accommodation Coefficienta) α=1.00b) α=0.80c) Pilinski et al. 2010

Available Data: Fitted-Ballistic Measurements

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Rocket Body Orbits18:30:00, 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.

Available Data: Tri-Axial Accelerometers

10/28/2010 M. D. Pilinski, C. Turansky, B. M. Argrow 5

Y

X

Z

β

φ

β

aligned with

boomtowards Earth


SESAM Parameter Inversion

Fitted-Ballistic Coefficients t

t

t

t

B

B

, AtmosMod

obs,

, PhysMod

,obs

Results: SESAM model comparisons


fuel margin: -0.05% to

0.05%

fuel margin:-3% to 0%

fuel margin:-0.05% to 5.0%

Results: Comparison with Paddlewheel Measurements


CHAMP-GUVI Comparisons


α = 0.78 (+0.10, -0.13)

Tri-Axial Accelerometer Analysis

Diffuse model with incomplete accommodation10/28/2010 M. D. Pilinski, C. Turansky, B. M. Argrow 10

α = 0.89 (+0.02, -0.03)

Result Summary



Spacecraft Simulation Goals

10/28/2010

Numerical Simulations(e.g. DSMC)

Rigid-body dynamics(modeling/approximation)

Full dynamic simulation

(beyond drag)

• Redefine the problem from satellite drag to spacecraft fluid dynamics

Treat spacecraft dynamics more like aircraft dynamics where possible


DSMC Development

10/28/2010

Bird’s “production” codes DS2V, DS3V Current, best available option for DSMC

DS2V User Interface

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

The Good• Free, download at gab.com.au• Highly reliable• Verified by many people• Chemical reactions/internal modes present

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• 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

DSMC Development


1510/28/2010

Equations of Motion: 2D

�̇�=[𝑞𝑤+𝑋 (𝑢 ,𝑤 ,𝑞 , 𝑡)

𝑚

𝑞𝑢+𝑍 (𝑢 ,𝑤 ,𝑞 ,𝑡)

𝑚𝑀 (𝑢 ,𝑤 ,𝑞 ,𝑡)

𝐼 𝑦𝑦𝑞

]𝑋 (𝑢 ,𝑤 ,𝑞 ,𝑡)

𝒔 (𝑡)=[ 𝑢 (𝑡 )𝑤 (𝑡 )𝑞 (𝑡 )𝜃 (𝑡 ) ]

Source functions:

x

z

q

𝑽 ∞

𝛼

𝑍 (𝑢 ,𝑤 ,𝑞 ,𝑡)𝑀 (𝑢 ,𝑤 ,𝑞 ,𝑡)

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?

Rigid-Body Dynamics


1610/28/2010

separatrices

limitcycles

unstable trajectories

Aircraft-like Dynamics Results

NACA0012 in FM, Hypersonic flow: In-loop vs Sliding Taylor dynamic motion

Ma=10, Kn=100, Argon 1000K

𝛼0=15 ° 𝛼0=44 °


M. D. Pilinski, C. Turansky, B. M. Argrow 1710/28/2010

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

10/28/2010 18M. D. Pilinski, C. Turansky, B. M. Argrow

Thank You

Documents

Research Progress Satellite Drag in Free-Molecular and Transition Flow Focus Area VIII October 26, 2011 Marcin Pilinski, Craig Turansky, Brian Argrow University