Padova, Italy
Padova, Italy

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Lazzarin M.,Hit09 srl Padua | Bettella A.,Hit09 srl Padua | Manente M.,Hit09 srl Padua | Da Forno R.,MDA srl Treviso | Pavarin D.,Hit09 srl Padua
49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference | Year: 2013

A lumped-parameter model has been developed to study sloshing during ExoMars descent. This study is applied to a bladdered tank, modeled via CFD. ExoMars is the first Aurora Flagship mission to be assessed. Its aim is to characterize Mars biological environment in preparation for robotic missions and human exploration. The model is used to predict the forces and moments to which the descent module will be subjected, knowing the accelerations applied to the tank. These acceleration histories are used as the input of CFD simulations completing theoretical model validation. The model is derived from the basic physics of force and momentum balance. It is independent from the tank shape. Four different fill levels are investigated: 80%, 50%, 25% and 10% of the total tank volume available. Bladder shapes are determined through dedicated simulations re-creating the situation of emptying the tank from a certain fill level to the final desired one. To reach equilibrium, it is necessary to stop the liquid from flowing out (liquid velocity has to become zero everywhere within the reservoir). This way, the bladder reaches equilibrium as well; its shape is known and can be used for the simulations required for model calibration and validation. CFD approach for bladdered tanks has been validated against literature data, showing a maximum difference in the results lower than 15% when the bladder shape is determined using a dedicated CFD simulation. The analytical model has been calibrated using CFD simulations representing experiments. Tank response to sloshing has been derived with the calibrated analytical model and compared to CFD output.

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