Dynamic Aspects of Detonations (Progress in Astronautics and Aeronautics)
Poulter Laboratory MG 8/1/05 Large-Scale Hydrogen Deflagration and Detonations International...
-
date post
21-Dec-2015 -
Category
Documents
-
view
220 -
download
4
Transcript of Poulter Laboratory MG 8/1/05 Large-Scale Hydrogen Deflagration and Detonations International...
Poulter LaboratoryMG 8/1/05
Large-Scale Hydrogen Deflagration and
Detonations
International Conference on Hydrogen Safety8-10 September 2005
Pisa, Italy
M. GroetheE. MeriloJ. ColtonS. ChibaY. Sato
H. Iwabuchi
Poulter LaboratoryMG 8/1/05
• Objectives
• 300 m3 Open-Space Tests
• 1/5 Scale Tunnel Tests
• Partial Confinement Test
• Protective Blast Wall Test
• Large-Scale release (300 Nm3 H2)
• Summary
Outline
Poulter LaboratoryMG 8/1/05
• Acquire basic data on hydrogen deflagrations and detonations.
• Acquire hydrogen deflagration/detonation data for validation of computer simulations.
Objective
Studies were performed for IAE and administered through NEDO as part of the “Development for Safe Production and Utilization and Infrastructure of Hydrogen” program.
Poulter LaboratoryMG 8/1/05
300 m3
5.7 m
300 m3 Open-Space TestsObstacle-induced enhancement, scaling, free-field blast data.
• Deflagration tests with obstacles.
• Deflagration tests without obstacles.
• Detonation tests without obstacles.
Volume Blockage ratio: ~11%
Obstacle Test 0.46 m-diam X 3 m-tall
Poulter LaboratoryMG 8/1/05
Obstacle Test
~67 ms ~67 ms
~100 ms
• Standard and infrared video frames
Poulter LaboratoryMG 8/1/05
Deflagration Data
Overpressure Heat Flux
Scaled Overpressure Scaled Impulse
Poulter LaboratoryMG 8/1/05
Detonation Data
Heat fluxOverpressure
Scaled Overpressure Scaled Impulse
• Detonation data consistent with previous smaller scale tests
Poulter LaboratoryMG 8/1/05
Tunnel ExperimentsDeflagration, H2 release, Obstacle-induced enhancement.
• Homogeneous deflagration tests.
• Tests with and without scaled vehicles as obstacles.
• Scaled release and ventilation rates.
~ 1/5 scale
Poulter LaboratoryMG 8/1/05
Tunnel with Vehicle Models
Obstacles representingscaled vehicles.
Blockage ratio: 0.03
Poulter LaboratoryMG 8/1/05
Pressure and Impulse
Overpressure Impulse
Overpressure
•Overpressure and impulse unchanged by presence of vehicle models.
Poulter LaboratoryMG 8/1/05
H2 Release Tests
• Test 14 and Test 15: 0.1 kg H2 in 20 sec, no ventilation.
• Test 16: 0.1 kg H2 in 20 sec, 1.6 m3/sec ventilation rate.
• Test 17: 2.2 kg H2 in in 420 sec, 1.6 m3/sec ventilation rate.
H2 concentrationH2 concentration
• Ventilation significantly reduces H2 concentration
Poulter LaboratoryMG 8/1/05
Partial Confinement TestDeflagration enhancement from partial confinement.
• Narrow gap between two plates provides partial confinement
• Flame position measured by ionization pins.
• Overpressure measured inside and outside the source.
Poulter LaboratoryMG 8/1/05
Partial Confinement Test
Scaled Overpressure Scaled Impulse
~33 ms ~33 ms
Standard Video Frame IR Video Frame
• Confinement between plates does not enhance deflagration
Poulter LaboratoryMG 8/1/05
Protective Wall Tests Assess overpressure reduction by using a protective blast wall.
Test Layout
• 4 m-tall by 10 m-wide wall, 4 m from edge of the 5.3 m3 source• Stoichiometric deflagration (bottom, center spark ignition) • Pressure measured inside the source and in the free-field.
Poulter LaboratoryMG 8/1/05
Scaled Overpressure and Impulse
Scaled ImpulseScaled Overpressure
• Deflagration data suggests a reduction in overpressure and impulse.• Previous tests with a 2 m-tall wall show reductions up to 30%.
Poulter LaboratoryMG 8/1/05
Large-Release Test Rapid release of a large quantity of hydrogen that is ignited.
•300 Nm3 H2 (27 kg) released
in about 30 seconds.•Spontaneous ignition occurred
at ~360 milliseconds.
Tower
Nozzle
Releasevalve
Table with drywall insert
EstimatedFlame Jet
18-m tower
Sample station
Sample station
NozzleIgniters (15mJ)
Pressure and heat flux
Sample station
Poulter LaboratoryMG 8/1/05
Release to Free Field Static
Hydrogen Amount about 5 m 3 NTP 11 m 3 NTP
Hydrogen Concentration
heterogeneous homogeneous (30 vol % , 37 m3)
Status at Ignition Turbulent Static
Flame Propagation Velocity
about 100 m/sec 44 m/sec
Pressure Measurement
Range from Ignition Peak Overpressure
(kPa)
Impulse (Pa-s)
Peak Overpressure
(kPa)
Impulse (Pa-s)
(5.3m) 5.6 (5.3m) 40 (5.9m) 4.4 (5.9m) 122
11 m 3.8 25 2.9 82
21 m 2.3 13 1.7 44
Large-Release Test
Poulter LaboratoryMG 8/1/05
Summary
1 M. Groethe, J. Colton, S. Chiba, and Y. Sato, “ Hydrogen Deflagrations at Large Scale,” 15th World Hydrogen Energy Conference, Yokohama, Japan, 27 June - 2 July, 2004.
• Large-scale 300 m3 open space deflagrations and detonations.- Large obstacles do not enhance the deflagration.- Detonation data consistent with smaller scale tests and analytic expressions.
• Partial confinement of mixture between two plates.- Deflagration was not enhanced for this geometry.
• 1/5 scale tunnel tests.- Homogeneous deflagrations show near constant overpressure and impulse - 30% H2 blast is much higher than the free-field case. - Vehicle models do not enhance deflagration (BR = 0.03, which is small)- Ventilation of the tunnel significantly reduces the H2 concentration.
• 4 m-tall protective blast wall.- Blast reduction is suggested to over twice the wall height.- Previous tests and calculations show a reduction that diminishes with
range1.
• Large-scale release of hydrogen.- Release spontaneously ignite producing a blast followed by a flame jet.
- Ignited release produced a higher blast pressure and lower impulse than astatic homogeneous deflagration.