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

MABS22 Bourges, France 2012

Operation DISTANT PLAIN 1966

MABS22 Bourges, France 2012

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

MABS22 Bourges, France 2012

Primary Shock Radius-Time Trajectory Analysis

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

MABS22 Bourges, France 2012

Propane+oxygen

Propane only

MABS22 Bourges, France 2012

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

MABS22 Bourges, France 2012

Smoke Tracer Trajectory Used as the Piston Path

MABS22 Bourges, France 2012

MISERS GOLD

2.445 KT ANFO

SURFACE BURST

Use of an Arbitrary Piston Path

MABS22 Bourges, France 2012

Radius

Tim

e

ObservedShock trajectory

CalculatedShock trajectory

ArbitraryPiston Path

Use of an Arbitrary Piston Path

MABS22 Bourges, France 2012

Radius

Tim

e

ObservedShock trajectory

CalculatedShock trajectory

ArbitraryPiston Path.

Use of an Arbitrary Piston Path

MABS22 Bourges, France 2012

Radius

Tim

e

ObservedShock trajectory

CalculatedShock trajectory

ArbitraryPiston Path.

Comparison of Observed and Calculated Shock Trajectories

MABS22 Bourges, France 2012

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

MABS22 Bourges, France 2010

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

The PP-RCM Calculated the Physical PropertiesThroughout the Flow Field

MABS22 Bourges, France 2010

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

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

The PP-RCM Calculated the Physical PropertiesThroughout the Flow Field

MABS22 Bourges, France 2010

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)

The PP-RCM Calculated the Physical PropertiesThroughout the Flow Field

MABS22 Bourges, France 2010

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)

The PP-RCM Calculated the Physical PropertiesThroughout the Flow Field

MABS22 Bourges, France 2010

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)Particle Velocity – U/a0

The PP-RCM Calculated the Physical PropertiesThroughout the Flow Field

MABS22 Bourges, France 2010

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)Particle Velocity – U/a0

Calculated Properties

Dynamic Pressure, Temperature and Sound Speed

Results

MABS22 Bourges, France 2012

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

MABS22 Bourges, France 2012

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

MABS22 Bourges, France 2012

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

MABS22 Bourges, France 2012

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

MABS22 Bourges, France 2012

Radius (m/kg^1/3)

1 10

Overpressure Im

pulse (atm.s)

0.1

1

Log-log Plot of Impulse versus Scaled Radius

Summary

MABS22 Bourges, France 2012

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

Summary

MABS22 Bourges, France 2012

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