© 2008 SRI International
Large-Scale Testing: Part IMark GroethePoulter LaboratorySRI InternationalMenlo Park, CAUSA
21-30 July 2008University of Ulster
Belfast, UK
3rd ESSHS
2© 2008 SRI International
Outline
• Background• Experiments
– Open Space
– Open Space with Obstacles
– Protective Blast Wall
• Summary
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SRI headquarters, Menlo Park, CA
Sarnoff Corporation, Princeton, NJ
Who we areSRI is a world-leading independent R&D organization
• Founded by Stanford University in 1946– A nonprofit corporation founded “To promote and foster the
application of science in the development of commerce, trade,and industry … the improvement of the general standard ofliving … and the peace and prosperity of mankind.”
– Independent since 1970
– Sarnoff Corporation acquired in 1987 (formerly RCALaboratories)
• Combined power of over 2,100 staff members
SRI – State College, PA SRI – Washington, D.C.SRI – Tokyo, Japan
• Bangalore
• Taipei
• Beijing
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Successful innovationsYou likely use an SRI innovation every day
.com
.gov
.org
Post office letter sorting
10 Emmys for HDTV, color TV…
Anti-malaria drug
ARPAnet, start of the internet
Electronic banking
Motors and actuators
Computer mouse (1964),
windows, hypertext, …
Robotic virtual reality surgery
Academy Award
Electrostatic discharge rods
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• Established in 1954- Named after the founder, Thomas “Doc” Poulter
• Research on effects of explosions,impacts, and fire
• State-of-the-art computationalmodeling
• Scale model structures testing
• Extensive fielding experience
• Large explosive tests performedat CHES*
* Corral Hollow Experiment Site
Poulter Laboratory has
custom-designed a wide variety
of experiments to investigate
unique problems of
impacts and explosions
CHES
Poulter Laboratory
6© 2008 SRI International
• Large natural gaspipeline ruptured by
explosive charge
• Gas ignited by flares
• Extensive pressureand temperature
measurements to
assess hazard
The world’s largest natural gas tire test wasconducted by SRI in Canada
7© 2008 SRI International
CM-6183-1
CalculationLayout
ComputationalMesh
10.0
7.5
5.0
2.5
0
DIS
TA
NC
E (
m)
Hydrogen Tank(Po = 1 MPa)
Rigid Structure
10.0
7.5
5.0
2.5
00 2.5 5.0 7.5 10.0
DISTANCE (m)0 2.5 5.0 7.5 10.0 0 2.5 5.0 7.5 10.0
t = 0 ms t = 4 ms t = 10 ms
M. Sanai, “Use of advanced computer simulation techniques and pressure-impulse methodology for investigation and mitigation of
postulated explosion accidents,” International Hydrogen and Clean Energy Symposium, Tokyo, Japan, February 1995.
Computer Simulation of a Hydrogen TankExploding Near a Rigid Structure (L2D Code)
8© 2008 SRI International
diffusion
coefficient
laminar burning
velocity=1
heat of
combustion
detonation
sensitivity=1
flammability
range
buoyancy
density
ignition energy
Hydrogen Properties
Directorate-General for Research Sustainable Energy Systems, “Introducing hydrogen as an energy carrier,” K I - N A - 2 2
0 0 2 - E N - C, Luxembourg: Office for Official Publications of the European Communities 2006, ISBN 92-79-00826-9.
9© 2008 SRI International
Hydrogen Safety Issues
Free-field blast
Confinement
Leak behavior
DDT
Ignition
Mitigation
375.564 ms 404.124 ms 565.964 ms
18 m
10© 2008 SRI International
The studies presented here have been
performed for NEDO in Japan, U.S. DOE, and
numerous private companies
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Open Space Experiments
12© 2008 SRI International
Open Space Experiments
Heat Flux Sensor
Ignition Source
Pressure Sensor
Time of Arrival
• Obtain fundamental free-field blast data on hydrogen deflagrations and detonations– Homogeneous hydrogen and air mixtures
– Lean, stoichiometric, and rich mixtures
• Assess scaling effects– Enclosure volumes have ranged in size from 5.3 m3 to 300 m3
13© 2008 SRI International
Purpose: Assess scaling effects, acquire free-field blast data
• Sources of cubic geometry
• Experiments with varying concentrations
5.3 m3 source
5.3 m3 and 37 m3 Experiments
37 m3 source
E. Merilo and M. Groethe, “Deflagration safety study of mixtures of hydrogen and natural gas in a semi-open space,” 2nd International
Conference on Hydrogen Safety (ICHS), San Sebastian, Spain, 11-13 September 2007.
Y. Sato, H. Iwabuchi, M. Groethe, J. Colton, and S. Chiba, “Experiments on Hydrogen Deflagration,” 8th Asian Hydrogen Energy
Conference, Tsinghua University, Beijing, China, 26-27 May 2005.
14© 2008 SRI International
• The plastic film tent is cut prior to mixture ignition to minimizeconfinement of the displacement flow.
• Must not ignite the hydrogen-air mixture.
Plastic film
Glass
tubeRubber hose
& MDF
Obstacle
Cross section
0.008 mm
plastic film
MDF*
Tent
frame
Rubber
hose
Glass
tube
* mild detonating fuse (MDF)
The rubber hose expands and shatters
the glass tube severing the plastic film.
M. Groethe, J. Colton, and S. Chiba, “Hydrogen deflagration safety studies in a semi-open space,” 14th World Hydrogen
Energy Conference, Montreal, Québec, 9-13 June 2002.
Tent Cutting
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37 m3 Experiments
Plastic
confinement
cut prior to
ignition
Y. Sato, H. Iwabuchi, M. Groethe, J. Colton, and S. Chiba, “Experiments on hydrogen deflagration,” 8th Asian Hydrogen Energy
Conference, Tsinghua University, Beijing, China, 26-27 May 2005.
16© 2008 SRI International
Assess scaling effects, acquire free-field blast data
• Experiments with varying concentrations
300 m3 Experiments
M. Groethe, E. Merilo, J. Colton, S. Chiba, Y. Sato, and H. Iwabuchi, “Large-scale hydrogen deflagrations and
detonations,” International Journal of Hydrogen Energy, Volume 32, Issue 13 (September 2007) pp. 2125-2133.
17© 2008 SRI International
Stoichiometric Detonation
M. Groethe, E. Merilo, J. Colton, S. Chiba, Y. Sato, and H. Iwabuchi, “Large-scale hydrogen deflagrations and
detonations,” International Journal of Hydrogen Energy, Volume 32, Issue 13 (September 2007) pp. 2125-2133.
18© 2008 SRI International
Stoichiometric Detonation
High-Speed Video Frames
M. Groethe, E. Merilo, J. Colton, S. Chiba, Y. Sato, and H. Iwabuchi, “Large-scale hydrogen deflagrations and
detonations,” International Journal of Hydrogen Energy, Volume 32, Issue 13 (September 2007) pp. 2125-2133.
19© 2008 SRI International
Scaled Overpressure
Heat Flux
Scaled Impulse
Overpressure
M. Groethe, E. Merilo, J. Colton, S. Chiba, Y. Sato, and H. Iwabuchi, “Large-scale hydrogen deflagrations and
detonations,” International Journal of Hydrogen Energy, Volume 32, Issue 13 (September 2007) pp. 2125-2133.
Detonation Data
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Open Space Experiments
With Obstacles
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• Obstacle experiments (obstacles produce turbulence)
• Obstacles caused DDT
• Obstacles structure based on the MERGE/EMERGE design
Purpose: Assess unconfined turbulent combustion
Detail
Volume blockage: 10.9%
5.3 m3 Experiments
M. Groethe, J. Colton, and S. Chiba, “Hydrogen deflagration safety studies in a semi-open space,”
14th World Hydrogen Energy Conference, Montreal, Québec, 9-13 June 2002.
22© 2008 SRI International
Plastic film fragment size correlates with tabulated
detonation cell width.
Obstacle,
30% H2
No-obstacle,
30% H2
M. Groethe, J. Colton, and S. Chiba, “Hydrogen deflagration safety studies in a semi-open space,”
14th World Hydrogen Energy Conference, Montreal, Québec, 9-13 June 2002.
Cell
Wid
th (
mm
)
Plastic Tent Fragments
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Deflagration enhancement from partial confinement
• 10 mm gap between two plates provides partialconfinement.
• No enhancement observed. Perhaps a wider ornarrower gap may result in enhancement?
IR Video Frame
~33 ms
Partial Confinement Test
M. Groethe, E. Merilo, J. Colton, S. Chiba, Y. Sato, and H. Iwabuchi, “Large-scale hydrogen deflagrations and
detonations,” International Journal of Hydrogen Energy, Volume 32, Issue 13 (September 2007) pp. 2125-2133.
Scaled Overpressure Scaled Impulse
24© 2008 SRI International
Assess scaling effects; acquire free-field blast data
• Experiments with and without obstacles
Volume Blockage ratio: ~11%
300 m3
5.7 m
300 m3 Experiments
M. Groethe, E. Merilo, J. Colton, S. Chiba, Y. Sato, and H. Iwabuchi, “Large-scale hydrogen deflagrations and
detonations,” International Journal of Hydrogen Energy, Volume 32, Issue 13 (September 2007) pp. 2125-2133.
25© 2008 SRI International
~67 ms ~67 ms
~100 ms
• No enhancement is observed for 300 m3 obstacles
• Obstacle size or shape effect?
Obstacle Experiment
M. Groethe, E. Merilo, J. Colton, S. Chiba, Y. Sato, and H. Iwabuchi, “Large-scale hydrogen deflagrations and
detonations,” International Journal of Hydrogen Energy, Volume 32, Issue 13 (September 2007) pp. 2125-2133.
26© 2008 SRI International
Overpressure Heat Flux
Scaled Overpressure Scaled Impulse
M. Groethe, E. Merilo, J. Colton, S. Chiba, Y. Sato, and H. Iwabuchi, “Large-scale hydrogen deflagrations and
detonations,” International Journal of Hydrogen Energy, Volume 32, Issue 13 (September 2007) pp. 2125-2133.
Deflagration Data
27© 2008 SRI International
Mitigation:
Protective Blast Wall Experiments
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Reduced pressure
region
Explosion
source
Shock wave
Wall
Wave
diffracts
Wave
reforms
Unaffected
by wall
Blast Walls
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Blast Wall Experiments
Two areas of research involving blast walls
• Evaluate the reduced pressure region created by the blast wall
• Measure the response of the blast wall to the explosive event
Wall5.3 m3
Source
Blast
sensors
10 m
4 m
Wall ResponsePressure Reduction
30© 2008 SRI International
Blast Wall Experiments Purpose: Assess overpressure reduction by using a blast wall
Calculations (CTH): significant reduction in blast to over twice the height of the wall for specific
locations. Data indicate the reduction could be as much as 30%.
M. Groethe, E. Merilo, J. Colton, S. Chiba, Y. Sato, and H. Iwabuchi, “Large-scale hydrogen deflagrations and
detonations,” International Journal of Hydrogen Energy, Volume 32, Issue 13 (September 2007) pp. 2125-2133.
Scaled Impulse
Scaled Overpressure
31© 2008 SRI International
Y. Suwa et al., “Design of safe hydrogen refueling stations against gas-leakage, explosion and
accidental automobile collision,” WHEC 16, Lyon, France, 13-16 June 2006.
Protective Blast Wall Experiments: Structural Response
32© 2008 SRI International
Reinforced Concrete Wall Response
Cracks and Damage
1-m-high walls
Time (s)
Y. Suwa et al., “Design of safe hydrogen refueling stations against gas-leakage, explosion and
accidental automobile collision,” WHEC 16, Lyon, France, 13-16 June 2006.
Wall Displacement
Collapse of 1-m-high wall
33© 2008 SRI International
Summary
• Open Space Experiments– Assess scaling effects, acquire free-field blast data
• Open Space with Obstacles– Small-scale obstacles have shown significant enhancement of explosions
– Large-scale obstacles have not significantly enhanced explosions
• Protective Blast Wall Experiments– Reduction in overpressures behind the walls
34© 2008 SRI International
Stay tuned, Part II coming up
• Large Release Experiments
• Confined Explosions