DLR Portal
Home|Textversion|Imprint|Sitemap|Contact Imprint Privacy |Deutsch
You are here: Home:News
Advanced Search
Contact
Research
Members of Staff
News
Publications
News
Back
Print

Parabolic Flight: Sound in Granular Matter



Jan Haeberle, Matthias Sperl, Peidong Yu, Alex Kamphuis and Jeremy Perrin
in front of the parabolic flight rack inside the Airbus A310 Zero-G.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

For the characterisation of granular matter, several experimental methods
are available. For dense packings an established method is the transport
of sound waves. It is well known that for higher pressure on the granulate
packing the speed of sound increases. So for high pressures, granular
matter behaves similar to liquids: The speed of sound varies with the
pressure, but not with the amplitude of the sound wave. For very low
pressure, however, one is close to a transition where the overall granular
packing loses its mechanical stability and the individual particles begin
to lose the contacts among each other. Simultaneously, additional contacts
can be established in this regime by sound waves. In this parameter range,
the speed of sound varies with the wave amplitude.

This unusual behavior of sound in granular matter was probed during the
28th DLR parabolic flight campaign in March 2016. To this end, the
different arrival times of a sound wave along the probe cell was
determined.


Copyright © 2021 German Aerospace Center (DLR). All rights reserved.