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63rd International Astronautical Congress 2012, Naples, Italy
LARGE SCALE EXPERIMENTS ON SPACECRAFT
FIRE SAFETY IAC-12. A2.2.2
DAVID L. URBAN & GARY A. RUFF: NASA GLENN RESEARCH CENTER, USA
OLIVIER MINSTER & BALAZS TOTH: ESA ESTEC, NOORDWIJK, NETHERLANDS
A. CARLOS FERNANDEZ-PELLO: UC BERKELEY, BERKELEY, CALIFORNIA, USA
JAMES S. T'IEN: CASE WESTERN RESERVE UNIVERSITY, CLEVELAND, OHIO, USA
JOSE L. TORERO & ADAM J. COWLARD: UNIVERSITY OF EDINBURGH, EDINBURGH, UK
GUILLAUME LEGROS: UNIVERSITE PIERRE ET MARIE CURIE, PARIS, FRANCE
CHRISTIAN EIGENBROD: UNIVERSITY OF BREMEN (ZARM), BREMEN, GERMANY
NICKOLAY SMIRNOV: MOSCOW LOMONOSOV STATE UNIVERSITY, MOSCOW, RUSSIA
OSAMU FUJITA: HOKKAIDO UNIVERSITY, SAPPORO, JAPAN
SEBASTIEN ROUVREAU: BELISAMA R&D, TOULOUSE, FRANCE
GRUNDE JOMAAS: TECHNICAL UNIVERSITY OF DENMARK, KGS. L YNGBY, DENMARK
https://ntrs.nasa.gov/search.jsp?R=20130000677 2020-06-15T10:00:49+00:00Z
Spacecraft Fire Safety Demonstration
Project Objective:
• Advance spacecraft fire safety technologies identified as gaps by the Constellation Program and in the Exploration Technology Roadmaps
• Demonstrate performance of these technologies in a large-scale, low-gravity spacecraft fire safety test aboard an unmanned re-entry vehicle
- Demonstration of this operational concept could allow future experiments to investigate additional fire safety technologies and protocols
Experiment Objective:
Determine the fate of a large-scale microgravity fire 1. Spread rate, mass consumption, and heat
release
• Is there a limiting size in microgravity? 2. Confirm that low- and partial-g flammability
limits are less than those in normal gravity
• Are drop tower results correct?
Most U. S. agencies responsible for large transportation systems conduct full-scale fire tests to address gaps in fire safety knowledge and prove equipment and protocols.
FAA full scale aircraft test
Naval Research Laboratory Ex-USS Shadwell
Controlled burns of structures
Orbital Science's Cygnus ESA's ATV approaching ISS approaching the ISS
2
Implications of Fire Growth Rate
• Almost no information exists on large-scale fire growth in microgravity
• CO2 concentration approximately scales with mass of material consumed
• Safety-critical parameters such as temperature and pressure scale with mass consumed and rate of mass consumption
• Growth rate information is needed to make informed decisions on safety equipment and crew response
Pressure relief valve sizing Extinguisher size Consumables for cabin cleanup Crew response times (fight-or-flee decisions)
• Data will validate modeling of spacecraft fire response scenarios
500
G450
o
Non-survivable Fire
100
Firc Grnwth C .. cfficient (kWI./) a = 0.0029 a = 0.04(}9
Cv =3.0 .l
Vehicle Volume = 953 fi Packing actor = 0.50 Pres ure Relief Valve = 1.1 aIm (1.05 afm crack)
Survivable Fire
200 300 400 500~ec
Time frnm start of tire ( .. fee)
1.6
1.5
-a ;J!
1.2 -
1.1
I.U
3
Experiment Justification
• NASA-STD-6001 describes the test methods used to qualify materials for use in space vehicles.
• The tests cover flammability, odor, off-gassing, and compatibility.
• The primary test to assess material flammability is Test 1: Upward Flame Propagation
Subs~ral& 'or tes1ing ot cO<aJtin QS ,
Typir;all spccimen -
Umltlll '~Iame
spread heilghl
Paper shoot
i
9
,
-
-'
be 10\\1'
specimen -
~vpl'~I I" " ~ ~ Test
chamber
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'--' "~ .. '--. .1 "- II I / ..,.,.,.,.. Igl'il1it(!t
:ZOltlin .. ::; ~ .,.
"' - --- / ---
Test 1 Apparatus
• Materials "pass" this test if the flame self-extinguishes before it propagates 15 cm
• Maximum oxygen concentration (MOC) is defined as the highest O2 at which material passes Test 1
• Flammability limits determined by this test are strongly influenced by natural convection
• Drop tower data shows that flammability limits are lower in low- and partialgravity!
• Do NASA's flammability standards result in higher flammability limits than actually found in low-gravity?
4
Low- and Partial-g Flammability Limits
• Tests were conducted at WSTF (normal-g) and GRC (Iow- and partial-g) to quantify changes in the flammability limit for Nomex, Mylar, and Ultem at low (with convective flow), Martian, and Lunar gravity levels.
• Data on right shows Oxygen Margin of Safety (negative means material burns at lower 02 compared to normal gravity!)
(OMOS = MOC)o_g - MOC)1_g)
Centrifuge drop rig being prepared for a drop in the Zero Gravity Facility
Dome
Experiment support plate
Control hardware and electronics
1
o
VI o -2-~ ~ >-... -3
.!!! III
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no ... III
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o -6
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6.
Mylar
Q ~ - 0
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-B-Normal Gravitv Natural Comfcction
<> Marl.i <'ln Gr ' vi ty l'J a l.uriJI (on·.eel ion
I!J. l una r Gravit'{ Natura l Conve·: t ion
o Zero Gravity Forccd Convect ion
Ultem Nomex
~ Flammability limit samples in the Spacecraft Fire Safety Demonstration Experiment will evaluate NASA-STD-6001 Test 1 in low-g and validate drop tower results.
5
Flow
Flow
Mission Concept
Load experiment into Cygnus PCM
Cygnus mounted in the shroud of the Antares vehicle Antares (Tau res 2) V launch
7
Mission Concept
Cygnus approaching ISS Unpack cargo, reload with trash
Proposed location of the SFS Demo experiment (back of vehicle)
Check-out SFS Demo experiment
8
SFS Demo Experiment Configuration
• Experiment remains on AFT wall but rotated to lie between the rails • Sample spacing requirements met • Length of flow chamber reduced from 48" to 44" • Camera enclosures facing M-01/M-02 bags on AFT wall
SFSD Expermenwith 44" Flow Chamber Displaces One M-01 CTe and One M-02 CTe
NAS
AO
psEn
gr.
Cyg
nus
Ops
Engr
.
VOIC
E
Flow
Flow
Safety Considerations - Overpressure testing
Vacuum Faculty (VF)-13) 149.9 cm 10 360 cm high 6.35 m3 volume
<C Vi [l.
~.
::::J
'" '" Qj
&:
11.82
11.8
11.78
11.76
11.74
11.72
11.7
11.68
11.66
11.64
a 200 400 600 800
time, s from ignition start
Pressure trace for Single 12.5- by 100-cm sample ignited at the top. The fuel is 90 grade cotton cheese-cloth with a 4.92 mg/cm2 density.
12
Calculation initialization
• Calculations are initialized with a steady state flow generated by the fans at constant temperature following a classic strategy:
• Flow initialization
• Full multigrid initialization
• Few thousands iterations with first order solver
• Few thousands iterations with second order solver
• Flow modelling main parameters: • Energy equation turned on
• Turbulence model: Ke-RNG
• Air as ideal gas for density calculation
• sutherland model for viscosity
• Initial temperature: 300k
• Initial pressure: 1013 hPa
• All walls are adiabatic
,
~.
Calculation with heat release ATV configuration
• 1- ATV configuration after 1 minute of heat release • Pathlines • Velocity field • Temperature field
6.73e-01
6.3ge-01
6 05e-01
5.72e-01
5389-01
5.04e-01
4.71e-01
4.37e-01
4.04e-01
3.709-01
3.36e-01
303e-01
2.6ge-01
2 35e-01
2.02e-01
1689-01
1.35e-01
1019-01
6.73e-02
3.36e-02
O.OOe+OO
Pathlines Colored by Velocity Magnitude (m/s) (Time=6.0000e+01) Sep 06, 2012 ANSYS FLUENT 14.0 (3d, dp, pbns, rngke , transient)
673.01
639.01
605.01 572e-Ol
538e-Ol
504&-01
<1719-01
"37e-Ol 404e-Ol
370.01
336&-01
303H11
269e-Ol
2359-01
202&-01
168e-Ol
1509+03
1448"03
1389"03
13260+03
1269"03
120s"03
114e+03
108e4 03
102e"03
9609+02
9 QOe."02 84060+02
780e+02
7209-02
6609·02
SYS
Sep 06 , 20 12 ANSYS FLUENT 1 • . 0 (3d. dp . pbns, rngke. transient)
SYS
Sap 06 , 20 12 ANSYS FLUENT 1 • . 0 (3d. dp . pbns , rngke. transient)
Conclusions
• Microgravity fire behaviour remains poorly understood and a significant risk for spaceflight
• An experiment is underdevelopment that will provide the first real opportunity to examine this issue focussing on two objectives
• Flame Spread
• Material Flammability
• This experiment has been shown to be feasible on both ESA's ATV and Orbital Science's Cygnus vehicles with the Cygnus as the current base-line carrier.
• An international topical team has been formed to develop concepts for that experiment and work towards its implementation.
• Pressure Rise prediction
• Sample Material Selection
• This experiment would be a landmark for spacecraft fire safety with the data and subsequent analysis providing much needed verifications of spacecraft fire safety protocol for the crews of future exploration vehicles and habitats.
15
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