Modelling the Ignition of Modular Charges...03 Five – 10g black powder per module Igniter in last module not ignited Module 2 might ignite first Taking 600K as the propellant ignition

QinetiQ/D&TS/WPNS/PUB0701309

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April 2007

© Copyright QinetiQ limited 2007

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Modelling the Ignition of Modular ChargesClive Woodley & Steve Fuller

A presentation to: 42nd Guns & Missiles Conference

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www.QinetiQ.com2© Copyright QinetiQ limited 2007

Contents

01 Background

02 Validation

03 Simulations

04 Conclusions & future work

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01Background

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01 Charge design – why UPCS?

Existing inventory replaced with 1 module

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01 Charge design – advantages of UPCS

• Current charges− Not fully IM compliant

− Not cleared for A1/C2 climatic conditions

− Wasteful – decremental system

− Costly & L10 can’t routinely be used for training

− Often remain in WMR until they ‘life out’

• With UPCS− Same charges are used in training as are deployed for war fighting

− Training simplified/more realistic

− Substantial cost savings can be achieved through incremental system

− Logistic burden reduced

− Autoloader compatible

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01 Modular charges – the problem being addressed

Safety & performance are important requirements – linked to ignition

• Pressure waves eliminated or minimised and consistent

• Simultaneous ignition along length of charge

• Combustible cartridge cases present barrier to flamespread along the propellant bed

• Modules act as projectiles!

-20

-10

0

10

20

30

0 5 10 15 20 25

Time (ms)

Pres

sure

diff

eren

ce (M

Pa)

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01 Modelling approach - QIMIBS

2D mortar code

• Developed initially with MOD funding

• Developed further using QinetiQ funding

• Details presented at 22nd

International Symposium on Ballistics

• Ability to represent internal solid boundaries

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02Validation

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02 Primer only – single module – initial geometry

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02 Primer only – single module

0.000.050.100.150.200.250.300.350.40

0 2 4 6 8 10

Time (ms)

Pre

ssur

e (M

Pa)

QIMIBS P1 QIMIBS P2Round 4 P1 Round 4 P2

0.00

0.05

0.10

0.15

0.20

0.25

0 2 4 6 8 10

Time (ms)

Pre

ssur

e (M

Pa)

QIMIBS P1 QIMIBS P2Round 1 P1 Round 1 P2

1.43g black powder

Max velocity measured: 1.5m/s

Max velocity predicted: 3.2m/s

1.25g NC

Max velocity measured: 2.0m/s

Max velocity predicted: 5.0m/s

Correct trend predicted for pressure and module velocity

Module velocities overpredicted but no account taken of sliding resistance

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02 5 modules - flamespread

0

1

2

3

4

5

6

0 0.2 0.4 0.6 0.8 1

Distance from breech (m)

Tim

e of

firs

t vis

ible

ligh

t (m

s)

Test 1Test 2Simulation

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03Simulations

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03 Simulations

• Single module− Igniter mass & location

− Flash tube diameter & vent hole size

• Three modules

• Five modules

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03 Single module – igniter mass (5g top, 15g bottom)0.5ms 1.0ms

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03 Single module – igniter mass

200

400

600

800

1000

1200

1400

1600

1800

0 5 10 15Time (ms)

Tem

pera

ture

(K)

5g P6 5g P5 5g P415g P6 15g P5 15g P4

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03 Single module – effect of igniter position

0200400

600800

1000

1200

140016001800

0 2 4 6 8 10 12 14 16

Time (ms)

Tem

pera

ture

(K)

Outside P6 Outside P5 Outside P4Inside P6 Inside P5 Inside P4

0200400

600800

1000

1200

140016001800

0 2 4 6 8 10 12 14

Time (ms)

Tem

pera

ture

(K)

Outside P6 Outside P5 Outside P4I/O P6 I/O P5 I/O P4

Outside = outside module but inside flash tube

Inside = inside module but outside flash tube

Modelling indicates better ignition if igniter material is both sides of the flash tube

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03 Single module – effect of flash tube diameter

Modelling indicates better ignition for 26mm flash tube diameter

200

400

600

800

1000

1200

1400

1600

0 2 4 6 8Time (ms)

Tem

pera

ture

(K)

52mm P6 52mm P5 52mm P426mm P6 26mm P5 26mm P4

200

400

600

800

1000

1200

1400

0 1 2 3 4 5 6 7 8

Time (ms)

Tem

pera

ture

(K)


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03 Single module – effect of flash tube hole size

Modelling indicates better ignition for 6mm flash tube holes

200

400

600

800

1000

1200

1400

0 2 4 6 8Time (ms)

Tem

pera

ture

(K)


200

400

600

800

1000

1200

1400

0 2 4 6 8Time (ms)

Tem

pera

ture

(K)


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03 Three modules – initial geometry

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03 Three modules – 10g black powder per module

Taking 600K as the propellant ignition temperature, propellant in 2nd & 3rd modules ignited 0.8ms & 1.7ms after the 1st module

Use another internal ballistics code to predict pressure waves

200

400

600

800

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1200

1400

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1800

0 2 4 6 8 10 12Time (ms)

Tem

pera

ture

(K)

P1 P2 P3P6 P5 P4

200

400

600

800

1000

1200

1400

1600

1800

0 2 4 6 8 10 12Time (ms)

Tem

pera

ture

(K)

P9 P8 P7P12 P11 P10

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03 Five modules – initial geometry

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03 Five – 10g black powder per module

Igniter in last module not ignited

Module 2 might ignite first

Taking 600K as the propellant ignition temperature, propellant in 2nd , 3rd & 4th

modules ignited 1ms, 2ms & 5ms after the 1st module – use another internal ballistics code for ΔP

200

400

600

800

1000

1200

1400

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1800

0 2 4 6 8 10 12 14

Time (ms)

Tem

pera

ture

(K)

P1 P2 P3P6 P5 P4

200

400

600

800

1000

1200

1400

1600

1800

0 2 4 6 8 10 12 14

Time (ms)

Tem

pera

ture

(K)

P9 P8 P7P12 P11 P10

200

400

600

800

1000

1200

1400

1600

0 2 4 6 8 10 12 14

Time (ms)

Tem

pera

ture

(K)

P15 P14 P13P18 P17 P16

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04Conclusions & future work

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04 Conclusions & further work

• QIMIBS has much of the functionality required to model MCS

• Validated for two primers for 1 & 5 modules

• Parameter studies showed

− 5g black powder per module not likely to ignite

− Best position of igniter is both sides of flash tube

− 26mm diameter flash tube better than 52mm and 20mm

− Reducing flash tube vent area predicted to produce better ignition

• Predictions for 5 modules show

− Primer and igniter insufficient to ignite (5th) module adjacent to the projectile

− Module 2 might ignite before module 1

− Possibility of significant ignition delay for 4th module

• 155mm gun firings planned & further modelling

• Conclusions likely to be very dependent on primers and geometries used in this study

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Documents

Modelling the Ignition of Modular Charges...03 Five – 10g black powder per module Igniter in last module not ignited Module 2 might ignite first Taking 600K as the propellant ignition