Analysis Of Fluid Actuation Principle And Motion Performance Of Magnetohydrodynamic Momentum Wheel

Megnetohydrodynamics(MHD)momentum wheel is a new type of actuator,which can control the output of angular momentum and torque by driving conductive fluid through electro-magnetic coupling.This device has the advantages of long life,high precision,shock resistance and low abrasion,which can make up for the vibration and abrasion problems of mechanical bearing control,having a broad application prospect in the field of micro satellite pose and micro vibration control.Based on the NavierStokes equations of incompressible fluid and the basic equations of magnetohydrodynamics,a complete transfer function model is established for the Hartmann flow of metallic fluid in a rectangular annular tube with input of current and voltage.The frequency response characteristics of momentum wheel are analyzed,and the effects of viscous force and boundary layer effect on the output index of momentum wheel are deeply investigated.Meanwhile,the type of input control signal is designed.By using the finite element simulation software COMSOL,the electro-magnetohydrodynamic coupling model of momentum wheel is established,and the motion characteristics of metal fluid are simulated and verified.Combined with the theoretical model derivation and simulation results,the influencing factors of conductive fluid velocity are analyzed,and the direction of momentum wheel performance improvement and optimization is obtained.According to the principle of MHD momentum wheel current control mode,a driving circuit based on high-power Darlington transistor is designed to finish the task of high current control,and the corresponding PCB and performance tests are completed.Aimed at the torque index of momentum wheel under the control of AC signal,the static torque test scheme is designed,and the test of performance is carried out to verify the rationality of the theoretical derivation.