Magneto Active Slosh Control System - MAPMD

Sloshing poses a serious challenge in the design of satellites, spacecraft and launch vehicles. Sloshing can be affected by either passive or active measures. Passive slosh damping through either fixed internal baffles or other propellant management devices (PMD) is effective for low-amplitude slosh at low fill fractions but is less effective for higher fill fractions and higher amplitude slosh. Further it reduces the available propellant volume inside the tank and requires significant mass budget to implement effectively. The Magneto-active Propellant Management Device (MAPMD) system includes the membrane floating on the propellant surface and a control system that utilizes low-power electromagnetic coils to detect the position of the membrane within the tank, assess the slosh state of the liquid within the tank, and apply appropriate magnetic forces to the floating membrane to suppress incipient slosh. The slosh test bed at Embry-Riddle Aeronautical University (ERAU) is an experimental setup consisting of a dynamic force balance with three movable arms attached to a single axis actuator from Aerotech called Linear Motion Actuator (LMA). A pair of FUTEK LCM 300 (Tension and Compression) dynamic load cell is attached at the end of each movable arms. The sensitivity of the load cell is rated at 250 lbs or 1112 N. These load cells measure the forces acting on tank walls and resolve them into forces and moments. Motion of the actuator is accomplished by a custom built LabVIEW code coupled with Aerotech’s soloist CP software at Embry-Riddle Aeronautical University. The test tank is a clear polycarbonate cylindrical vessel of diameter 6 inches and length 8 inches. The external control system consists of two external wire coils each consisting of 100 turns of 12-AWG magnet winding wire, and (2) programmable DC power supplies capable of providing 1A of current at 12V. The coils are spaced at intervals equal to the coil radius, effectively creating a series of Helmholtz Coils. The Helmholtz configuration is advantageous because it creates a region of uniform magnetic field between two coils when the current supplied to each coil is the same. As a result, over 90% of the tank volume can be subjected to a constant, static magnetic field enough to stiffen the membrane and suppress slosh. The proposed MAPMD addresses all the challenges stated above through a simple, innovative solution that could prove to be cost effective and lead to better control performance of satellites, space craft and launch vehicles

An Investigation of the Magneto-Active Slosh Control for Cylindrical Propellant Tanks Using Floating Membranes

The phenomenon of sloshing is a substantial challenge in propellant management, particularly in reduced gravity where surface tension-driven flows result in large slosh amplitudes and relatively long decay time scales. Propellant Management Devices (PMDs) such as the rigid baffles and elastomeric membranes are often employed to counteract motion of the free surface. In the present study, we investigate an active PMD that utilizes a free-floating membrane that, under an applied static magnetic field, becomes rigid and suppresses slosh. This semi-rigid structural layer can thereby replace bulky baffle structures and reduce the overall weight of the tank. In this paper, the membrane was fabricated using Metglas 2714A alloy in a weave pattern and the experiment was run for varying slosh amplitudes at a given magnetic field gradient using the slosh research facility at Embry Riddle Aeronautical University. The resultant force acting on the walls of the cylinder is recorded for each test run using a pair of load cells that are attached at the end of each movable arm. Computational Fluid Dynamics (CFD) simulations were setup with the parameters of the experiment to verify and validate the experimental setup. The result of this investigation provides information on the magnetic field gradient required to control certain amplitude of slosh or in other words, the maximum amplitude of slosh that can be controlled for a given magnetic field

An Investigation of the Magneto-Active Slosh Control for Cylindrical Propellant Tanks Using Floating Membranes

The phenomenon of sloshing is a substantial challenge in propellant management, particularly in reduced gravity where surface tension-driven flows result in large slosh amplitudes and relatively long decay time scales. Propellant Management Devices (PMDs) such as the rigid baffles and elastomeric membranes are often employed to counteract motion of the free surface. In the present study, we investigate an active PMD that utilizes a free-floating membrane that, under an applied static magnetic field, becomes rigid and suppresses slosh. This semi-rigid structural layer can thereby replace bulky baffle structures and reduce the overall weight of the tank. In this paper, the membrane was fabricated using Metglas 2714A alloy in a weave pattern and the experiment was run for varying slosh amplitudes at a given magnetic field gradient using the slosh research facility at Embry Riddle Aeronautical University. The resultant force acting on the walls of the cylinder is recorded for each test run using a pair of load cells that are attached at the end of each movable arm. Computational Fluid Dynamics (CFD) simulations were setup with the parameters of the experiment to verify and validate the experimental setup. The result of this investigation provides information on the magnetic field gradient required to control certain amplitude of slosh or in other words, the maximum amplitude of slosh that can be controlled for a given magnetic field