hopper-flow of lunar regolith simulants in reduced gravity and vacuum

1

7th Regional Americas Conference of the International Society for Terrain-Vehicle Systems

05 November 2013 | Tampa, Florida Technische Universität München

Institute of Astronautics

Hopper-Flow of Lunar Regolith Simulants

in Reduced Gravity and Vacuum

Philipp Reiss, Philipp Hager, Alexander Hoehn


Technische Universität München

[email protected]

05 November 2013

7th Regional Americas Conference of the ISTVS

Tampa, Florida

2




Scope of the Experiment

Investigating the flowability of lunar regolith simulants

under reduced gravity and vacuum

Background:

Geophysical sampling instruments on Moon

Problem of transporting regolith in feeding systems

?

Ph

oen

ix ©

NA

SA

SA

M ©

NA

SA

Here: Feed hopper

2

3




Flowability Parameters

Sample material Sample mass

Ambient pressure

Gravitation

Inclination angle of funnel

Outlet width of funnel

Funnel geometry

Vibration Wall friction Electrostatic charge

Moisture

Pre-consolidation

JSC-1A / NU-LHT-2M 27 to 46 g

0.07 to 6.10 mbar

1.00 / 0.38 / 0.16 g

55 / 60 / 65 / 70 / 75 deg

8 / 13 / 18 mm

Symmetrical / asymmetrical

3

4




Experiment Setup

Sample container

(PVC, PC)

Vacuum chamber

24 hopper configurations

4

5




Experiment Setup

Vacuum chamber with sample containers during operation

Experiment rack

5

6




Experiment Overview

24

Hopper configurations 2

Lunar regolith simulants

124

Parabolas

13x Mars-g (0.38g)

12x Moon-g (0.16g)

6x Zero-g (0g)

2-9 repetitions

during each parabola JS

C-1

A ©

US

GS

NU

-LH

T-2

M ©

Arn

old

Rein

ho

ld

~ 1000 Measurement

s

6

7




Flow Examples

Mars (0.38 g) Moon (0.16 g) Moon (0.16 g)

NU-LHT-2M

60 deg inclination

8 mm outlet

7

© P

hili

pp R

eis

s

8




Observations during Operation

• Gas inclusions slow the material flow.

• Material sticks to the walls of the sample container.

• Sample volume expands (lower bulk density).

• Random occurrence of arching and clogging.

• Material flow lasts longer than one parabola (at Moon-g, ~26 s).

Exemplary

video stills:

8

9




1

1.2

1.4

1.6

1.8

2

2.2

2.4

2.6

2.8

3

Sc

ale

fa

cto

r [-

]

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Sc

ale

fa

cto

r [-

]

Results and Conclusions

1. Flow rate is proportional to gravity.

2. Flow rate is proportional to outlet size.

3. For constant flow rate the outlet size is inversely proportional to the gravity.

9

8 mm 13 mm

18 mm 8 mm

JSC-1A

JSC-1A NU-LHT-2M

NU-LHT-2M

18 mm / 8 mm

13 mm / 8 mm

JSC-1A

JSC-1A NU-LHT-2M

NU-LHT-2M

0.38 g / 1 g

0.16 g / 1 g

1 g 0.38 g

0.16 g 1 g

Flow rate vs. gravity

(average and standard deviation)

Flow rate vs. outlet size

(average and standard deviation)

© P

hili

pp R

eis

s

10




Results and Conclusions

1. Flow rate is proportional to gravity.

2. Flow rate is proportional to outlet size.

3. For constant flow rate the outlet size is inversely proportional to the gravity.

4. Arching and clogging occurs randomly.

5. Higher inclinations tend to lead to higher flow rates.

6. Good repeatability and high flow rates for configurations with 65 deg, 70 deg, 8 mm, 13 mm.

7. Best repeatability and moderate flow rate for asymmetrical configurations.

10

11




Philipp Reiss


Technische Universität München

[email protected]

This work was supported by:

› Project LUISE-2 (DLR grant no. 50JR1210)

› German aerospace agency (DLR)

› European Space Agency (ESA)

› Centre National d'Etudes Spatiales (CNES)

› Novespace

› Kayser-Threde GmbH

› IGEP at Technische Universität Braunschweig

› ILM at Otto von Guericke Universität Magdeburg

hopper-flow of lunar regolith simulants in reduced gravity and vacuum

Technology