The instability in spacecraft was found to be the result of interaction between liquid lateral sloshing modes and the attitude control which tends to deviate the spacecraft from its trajectory. Sloshing phenomenon (refers to movement of liquid surface inside a container) can be seen in all vehicles that undergoes accelerated motion. Propellant slosh has major significance in automotive as well as aerospace industry. The proposed concept aims at preventing the occurrence of slosh during the mission as the amount of fuel decreases according to its burn rate. The rate of burn, in turn increases the amount of free space in the fuel/oxidizer tank, thus leading to the sloshing of fuel due to the gravitational and other forces acting on it.
The key innovation of the system is a simple hardware upgrade which reduces the sloshing in the tank nullifying the effect on desired projectile path. A further innovation, with respect to other methods for reducing sloshing is that the proposed system does not require any detailed information of the specific aerial vehicle. It uses several parameters easily gathered from the fuel level detection system in the algorithm.
The Fuel indicator sensor indicates the depleting fuel level data to the system using Level Sensors, Pressure Sensors, Depletion Sensors etc. The plunger is made up of materials like Vespel® as they are light weighted and do not add up to the structural weight. The algorithm is set in such a way the stepped linear motion actuator moves the plunger forward. The plunger compresses or reduces the area of the fuel tank causing no room for sloshing to take place or negligible slosh. As there is not much free space, the liquid-surface viscous interaction occurring in the system is almost nullified.
The system comprises of:
• An algorithm utilizing the Fuel level sensor data to initiate the motion of the actuator.
• A monitoring algorithm to check the functioning of the system.
• Stepped linear motion actuator system (patent pending) used to control the plunger displacement.
• Plunger to provide minimum clearance from the tank wall and movement.
In conclusion, the proposed system (patent pending) dramatically improves aerial vehicles safety, by providing an efficient, accurate and a clear display of reducing slosh, without requiring much change, thus enabling easy adoption by everyone. Moreover, the problematic interaction with the spacecraft's Attitude Control System is avoided by the nullified Slosh effect.