large-scale testing: part i - hysafe · 2008. 7. 27. · impacts, and fire • state-of-the-art...

© 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


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


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


• 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


• 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


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)


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.


Hydrogen Safety Issues

Free-field blast

Confinement

Leak behavior

DDT

Ignition

Mitigation

375.564 ms 404.124 ms 565.964 ms

18 m


The studies presented here have been

performed for NEDO in Japan, U.S. DOE, and

numerous private companies


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


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.


• 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


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.


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.


Stoichiometric Detonation




Stoichiometric Detonation

High-Speed Video Frames




Scaled Overpressure

Heat Flux

Scaled Impulse

Overpressure



Detonation Data



With Obstacles


• 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.


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


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



Scaled Overpressure Scaled Impulse


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




~67 ms ~67 ms

~100 ms

• No enhancement is observed for 300 m3 obstacles

• Obstacle size or shape effect?

Obstacle Experiment




Overpressure Heat Flux

Scaled Overpressure Scaled Impulse



Deflagration Data


Mitigation:

Protective Blast Wall Experiments


Reduced pressure

region

Explosion

source

Shock wave

Wall

Wave

diffracts

Wave

reforms

Unaffected

by wall

Blast Walls


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


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%.



Scaled Impulse

Scaled Overpressure


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


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


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


Stay tuned, Part II coming up

• Large Release Experiments

• Confined Explosions

large-scale testing: part i - hysafe · 2008. 7. 27. · impacts, and fire • state-of-the-art...

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