THE PHYSICAL PROPERTIES OF THE BLAST WAVE PRODUCED BY A STOICHIOMETRIC PROPANE/OXYGEN EXPLOSION

THE PHYSICAL PROPERTIES OF THE BLAST WAVE PRODUCED BY A STOICHIOMETRIC

PROPANE/OXYGEN EXPLOSION

MABS22 Bourges, France 2012

by

Maura C. Dewey & John M. Dewey

Dewey McMillin & Associates LtdVictoria, BC Canada

Operation DISTANT PLAIN 1966


Air Blast Time-of-Arrival Detectors (ABTOADS)

Recorder

An array of switches was closed by the primary shock,and the signals sent via a single cable to a recorder


Primary Shock Radius-Time Trajectory Analysis

Dewey (2005), J. Phys. D: Appl. Phys., 38, 4245-4251


Propane+oxygen

Propane only


The Piston Path – Random Choice Method (PP-RCM)G. I. Taylor (1946)

Smoke Tracer Trajectory Used as the Piston Path


MISERS GOLD

2.445 KT ANFO

SURFACE BURST

Use of an Arbitrary Piston Path


Radius

Tim

e

ObservedShock trajectory

CalculatedShock trajectory

ArbitraryPiston Path

Use of an Arbitrary Piston Path


Radius

Tim

e

ObservedShock trajectory

CalculatedShock trajectory

ArbitraryPiston Path.

Comparison of Observed and Calculated Shock Trajectories


Radius (m/kg^1/3)

0 5 10 15 20 25

Time (m

s/kg^1/3)

0

10

20

30

40

50

60

Propane/oxygen ABTOAD dataPP-RCM calculation

Propane/Oxygen ABTOAD DataPP-RCM Calculation

The PP-RCM Calculated the Physical PropertiesThroughout the Flow Field


Scaled Radius – 2 to 20 m/kg^1/3 at NTP




Scaled Time – 2 to 50 ms/kg^1/3 at NTP





Stored PropertiesHydrostatic Overpressure – OP (atm)






Density – ρ (atm)






Density – ρ (atm)Particle Velocity – U/a0






Density – ρ (atm)Particle Velocity – U/a0

Calculated Properties

Dynamic Pressure, Temperature and Sound Speed

Results


Overpressure (atm)

Time (ms/kg^1/3

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Overpressure (atm

)

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

PP-RCM data at 2.5 m/kg^1/3

Data Fitted to Modified Friedlander Equation


𝑃=𝑃𝑆𝑒−∝𝑡 ¿

Time (ms)

0 1 2 3

Overpressure (atm

)

-0.5

0.0

0.5

1.0

1.5

2.0

PP-RCM data at 2.5 m/kg^1/3Modified Friedlander Fit

Overdensity-Time History at 10 m/kg^1/3


Time (ms)

0 2 4 6

Overdensity (atm

) -0.02

0.00

0.02

0.04

0.06

0.08

0.10

0.12

PP-RCM DataModified Friedlander Fit

Particle Velocity Time History at 20 m/kg^1/3


Time (ms)

0 2 4 6

Particle V

elocity (u/a0)

-0.01

0.00

0.01

0.02

0.03

0.04

0.05

PP-RCM dataModified Friedlander Fit

Integration of the Equation over the Positive DurationProvides Quantities such as Impulse


Radius (m/kg^1/3)

1 10

Overpressure Im

pulse (atm.s)

0.1

1

Log-log Plot of Impulse versus Scaled Radius

Summary


All of the physical properties of a stoichiometricPropane/oxygen explosion have been characterised

Summary


All of the physical properties of a stoichiometricPropane/oxygen explosion have been characterised

It has been demonstrated that a hemispherical blast wave can be fully

characterised using a simple ABTOAD array

THE PHYSICAL PROPERTIES OF THE BLAST WAVE PRODUCED BY A STOICHIOMETRIC PROPANE/OXYGEN EXPLOSION

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