CCD camera

Honeycomb

Fan&Motor

PMMA：60mm x 10mm x 15,50,125m

Sample holder

Igniter (Ni-Cr wire)

O2 port

N2 port

Vacuum pump portClosed type wind tunnel (34cm x 19cm x 10cm)

Vane

Combustionchamber

He-Ne laserCCD camera

FringeSample

Schematic of experimental apparatus and interferometer systemSchematic of experimental apparatus and interferometer system

Time (msec)

G

-2000 -1000 0 1000 2000 3000 4000 5000 6000-2

0

2

4

6

8

10

12

G for 4.5 sec

Video camera

Sample holder(sample size: 6cm x 1cm)

Fan & MotorOpposed

Flow

Base

Solenoidcoil

Ni-Cr wire

Spring

turnable

Solenoid coil

Sample holder

Sample

Ignite the sample 1.6 sec before G.

Remove the igniter 0.3sec before G.

Details of sample holder and typical sequence of drop experimentsDetails of sample holder and typical sequence of drop experiments

Assemble

Move to the drop shaft

Close the capsule

Attach the transceiver

Ready to drop

MGLAB100m drop

21

3 4

min.

min.

extinct

Opposed flow velocity (mm/sec)

Sp

read

rat

e (m

m/s

ec)

O2 level: 50%O2 level: 30%O2 level: 21%

extinct

-100 -50 0 50 100 1500

2

4

6

8

10

12

14

min.

min.

extinct

Opposed flow velocity (mm/sec)

Sp

read

rat

e (m

m/s

ec)

O2 level: 50%O2 level: 30%O2 level: 21%

-150 -100 -50 0 50 100 1500

10

20

30

40

50

min.

min.

Opposed flow velocity (mm/sec)

Sp

read

rat

e (m

m/s

ec)

O2 level: 50%O2 level: 30%O2 level: 21%

extinct extinct

-100 -50 0 50 100 1500

1

2

3

4

5

6

**

The minimal value appears at Vg~-6cm/s

The minimal value appears at Vg~-3cm/s

The minimal value appears at Vg~0cm/s

Opposed flow velocity (mm/s)

150

90

60

30

0

Veqv estimated by Eq. 7 (mm/s)

30.84

21.02

15.51

9.22

0

The hydrodynamic constant, ch,FP, was determined by matching the computed and predicted spread rates.

V Veqv hyd g

65.2 ,PrRePr ,

2

1

4

1

,

4

1

,

FPhhFPhg

gFPhhyd ccxV

c

: 15m : 50m

: 125m

(Eq. 7)

Flame spread rate in microgravity with varying Flame spread rate in microgravity with varying ,V,Vgg and O and O22 level level(26th International Symposium on Combustion)

15m 50m125m

0.1 1 100

0.2

0.4

0.6

0.8

1

*

15m

50m 125m

15m 50m125m

0.1 1 100

0.2

0.4

0.6

0.8

1

*

15m 50m 125m

15m 50m125m

0.1 1 10

0

0.2

0.4

0.6

0.8

1

125m50m15m

Dimensionless spread rate vs. dimensionless relative flow velocityDimensionless spread rate vs. dimensionless relative flow velocity

: 50% : 30%

: 21%

Dimensionless radiation parameter, R

Thickness 15μ m

Thickness 50μ m

Thickness 125μ m

O2 level: 21% 0.24 0.8 2.0 O2 level: 30% 0.11 0.38 0.95 O2 level: 50% 0.04 0.14 0.34

Vf+Veqv ~10mm/sec

Vf+Veqv ~65mm/sec

Sizes of the preheat zone in microgravity and in normal gravitySizes of the preheat zone in microgravity and in normal gravity

normal gravitynormal gravity

micro-gravitymicro-gravity

Lgx

Lgy

Lgx

Lgy

Lgx~Lgy~0.27cm

Lgx~Lgy~1.7cm

= １ｃｍ

= １ｃｍ

Micro-gravityQuiescent conditionThickness: 50mO2 level: 50%

Normal-gravityQuiescent conditionThickness: 50mO2 level: 50%

Buoyant flow

Histories of temperature field near the flame frontHistories of temperature field near the flame front

Quiescent conditionThickness: 125mO2 level: 30%

Quiescent conditionThickness: 50mO2 level: 50%

The fringes move the opposed direction to that of flame spread, which implies that temperature is decreasing in time, thus unsteady.

The fringes move to the same direction that the flame moves, and it implies that the steady temperature field is achieved.

Photo Sketch Photo Sketch

R=0.95 R=0.14

Opposed flow velocity (mm/s)

15 micro-m O2: 50%

50 micro-m O2: 50%

125 micro-m O2: 50%

15 micro-m O2: 30%

50 micro-m O2: 30%

125 micro-m O2: 30%

15 micro-m O2: 21%

50 micro-m O2: 21%

-150 38.16 - - 23.29 - - - - -90 31.15 9.58 3.75 15.09 5.51 2.14 Extinct 4.64 -60 33.14 8.73 3.48 12.69 4.59 1.9 Extinct Extinct -30 33.96 7.50 3.17 14.79 3.46 2.16 Extinct fail to ignite 0 38.91 9.48 1.78 16.26 4.61 1.23 Extinct Extinct 30 42.62 10.27 3.58 19.29 5.5 3.16 Extinct fail to ignite 60 44.74 11.65 4.23 21.79 6.28 2.96 9.25 2.18 90 42.86 11.43 4.23 24.13 6.71 2.59 9.78 3.24 150 49.29 12.74 5.1 23.65 6.18 2.89 11.86 3.34

Opposed flow: Vg=0 Thickness: 50 mO2 level: 50%Pressure 1 atmFuel: Thin PMMA

Data from 4.5 s MGLAB Drop Tower Data from 4.5 s MGLAB Drop Tower QuiesceQuiescent Environment, Steady Spreadnt Environment, Steady Spread

Interferometer Video, Side View

CCD Video, Top View

Opposed flow velocity (mm/s)

15 micro-m O2: 50%

50 micro-m O2: 50%

125 micro-m O2: 50%

15 micro-m O2: 30%

50 micro-m O2: 30%

125 micro-m O2: 30%

15 micro-m O2: 21%

50 micro-m O2: 21%

-150 38.16 - - 23.29 - - - - -90 31.15 9.58 3.75 15.09 5.51 2.14 Extinct 4.64 -60 33.14 8.73 3.48 12.69 4.59 1.9 Extinct Extinct -30 33.96 7.50 3.17 14.79 3.46 2.16 Extinct fail to ignite 0 38.91 9.48 1.78 16.26 4.61 1.23 Extinct Extinct 30 42.62 10.27 3.58 19.29 5.5 3.16 Extinct fail to ignite 60 44.74 11.65 4.23 21.79 6.28 2.96 9.25 2.18 90 42.86 11.43 4.23 24.13 6.71 2.59 9.78 3.24 150 49.29 12.74 5.1 23.65 6.18 2.89 11.86 3.34

Opposed flow: Vg=0 Thickness: 125 mO2 level: 30%Pressure 1 atmFuel: Thin PMMA

Data from 4.5 s MGLAB Drop Tower Data from 4.5 s MGLAB Drop Tower Quiescent Environment - ExtinctionQuiescent Environment - Extinction

Interferometer Video, Side View

CCD Video, Top View

Opposed flow velocity (mm/s)

15 micro-m O2: 50%

50 micro-m O2: 50%

125 micro-m O2: 50%

15 micro-m O2: 30%

50 micro-m O2: 30%

125 micro-m O2: 30%

15 micro-m O2: 21%

50 micro-m O2: 21%

-150 38.16 - - 23.29 - - - - -90 31.15 9.58 3.75 15.09 5.51 2.14 Extinct 4.64 -60 33.14 8.73 3.48 12.69 4.59 1.9 Extinct Extinct -30 33.96 7.50 3.17 14.79 3.46 2.16 Extinct fail to ignite 0 38.91 9.48 1.78 16.26 4.61 1.23 Extinct Extinct 30 42.62 10.27 3.58 19.29 5.5 3.16 Extinct fail to ignite 60 44.74 11.65 4.23 21.79 6.28 2.96 9.25 2.18 90 42.86 11.43 4.23 24.13 6.71 2.59 9.78 3.24 150 49.29 12.74 5.1 23.65 6.18 2.89 11.86 3.34

Data from 4.5 s MGLAB Drop Tower Data from 4.5 s MGLAB Drop Tower Flow Reversal, 50 Flow Reversal, 50 m thick, 30% Om thick, 30% O22, 1 atm, 1 atm

Vg=30 mm/s Vg=0 Vg=-30 mm/s