The Study Of The Mechanical Properties Of The Floating Ball Structure On Restraining Sloshing In Propellant Tank

The liquid sloshing in fuel tanks has always been the research focus in the aerospace field.The sloshing has directly led to the failure of the space mission.How to inhibit the liquid sloshing of the launch vehicles is an important topic.In the aerospace engineering,all kinds of anti-sloshing structures are applied to the launch vehicles to restrain the sloshing in the fuel tank,the baffles are most frequently used.The baffles are always directly fixed on the inner wall of the propellant tank,which mainly are horizontal baffles and vertical baffles.Because these anti-baffles are usually fixed,they can’t adjust the height as the consumption of the fuel in the propellant tank.In order to ensure the effects of restraining sloshing,a plenty of baffles should be welded on the inner wall of the propellant tank,which will lead to the increase of the launch vehicle’s quality and the decrease of the carrying efficiency.The slosh damping of the liquid in the propellant tanks has to be increased,meanwhile the launch vehicles should be as light as possible,so the floating ball structure is adopted in this dissertation to reduce the splash of liquid fuel and the large-scale amplitude sloshing.It’s found that the foam on the surface of the drink can reduce the sloshing amplitude and help take the edge off.To dissipate the kinetic energy of water waves as much as possible,a layer of floating balls have been covered on the free surface of the liquid.The mutual friction between the floating balls can consume the sloshing energy,which will play a buffering effect in the process of the liquid sloshing.The numerical simulation and the sloshing experimental analysis are investigated to obtain the performance of liquid sloshing.In order to verify the suppression effect of the floating ball structure on the liquid sloshing,the sloshing of liquid under the conditions with or without the floating ball structure is compared respectively.The results have shown that the floating ball structure can really restraining the liquid sloshing.To reach the influence rule of the floating ball structure,the diameter and the material of the floating balls have been studied.Two kinds of materials of plastic floating balls have been chosen,and the size of the floating balls is divided into three kinds depending on the diameter.By comparing the sloshing condition with different diameters it’s found that the diameter of the floating balls can directly affect the inhibition effect of the liquid sloshing,and in a certain liquid height and external incentive there is an optimal size which will optimize the inhibition effect.This dissertation has studied the sloshing under two different materials.The results have shown that the floating balls with big elastic modulus can achieve better inhibition effect.In addition,the influence of the gravity center position of the floating balls’ change on liquid sloshing is also an important content in this dissertation.By filling the liquid in the floating balls the gravity center position of the floating balls has been changed,the weight of floating balls has been increased after filling the liquid,the contact area with the liquid surface has become larger.The floating balls can restrain the splash of the free surface.The spin of the liquid in the floating ball can also accelerate the dissipation of the internal energy.The results show that the floating balls which are filled with liquid have the better inhibitory effect on liquid sloshing,and the stable anti-sloshing performance can be maintained when the liquid level is changed.