Nutational damping in satellites

[vishal007win]

i want to ask ...how can i model sloshing of fuel in satellite feul tank , to an energy sink model...
can anybody help me?

 

[vishal007win]

in one of the experiment NASA has done, they have modeled this to pendulum model...but i want to incorporate energy dissipation to it too

 

[D H]

The typical approach for a moderate fidelity solution is a mass-spring-damper model.

This paper discusses a hybrid mass spring / pendulum model (with damping): http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050243594_2005246327.pdf

 

[Danger]

Wouldn't it be easier to use a slosh-free tank design, such as a mesh filler?

 

[D H]

Wouldn't it be easier to use a slosh-free tank design, such as a mesh filler?

A mesh doesn't stop slosh, but it can help attenuate it -- in the right circumstances.

Spacecraft designers do use meshes (isogrids) as one of several passive anti-slosh devices. See http://books.google.com/patents/about?id=cUoHAAAAEBAJ".

Unless the fuel tank is packed jam full with passive anti-slosh devices, there will always be slosh of some sort. Since slosh has resulted in multiple vehicle incidents, it is a very good idea to confirm via analysis and simulation that the passive anti-slosh devices and active slosh controls will work to keep the vehicle under control.

Everything you want to know about slosh: http://sloshcentral.bbbeard.org/.

 

[Danger]

Thanks, DH. That was very informative. I never realized how complex the matter is.

 

[vishal007win]

thanks DH..
i was looking for this only...
but one more thing to ask..
i m working with non-dimensionalzd equations
so wud it be more beneficial to work with damping ratio ς = c/2mω0. where m is the total mass of body...
or damping ratio ς = c/2mω0. where m is the mass of fuel...
hope u r getting what i m tryin to ask...