무인잠수정 추진기에 적용된 유체동압베어링의 안정성 향상을 위한 최적설계

Abstract

This paper proposes an optimal design of fluid dynamic bearings (FDBs) applied to a propulsor of an unmanned underwater vehicle (UUV) to improve the stability. The FDBs in propulsor decrease vibration of the rotating part of the UUV. The stiffness and damping coefficients are determined by solving the Reynolds equation and its perturbed equation of the coupled journal and thrust bearing. The critical-mass of the propulsor-bearing system is determined by solving the linear equation of motion. Optimal design is formulated by introducing the objective function of critical mass of FDBs and constraint equation of stiffness and damping coefficients. Fourteen major design variables of the FDBs were chosen for this optimal design. The rotating frequency of rigid propulsor-bearing system at steady state was evaluated. The response of optimal model was compared with that of the conventional model. Finally, we show the optimal model of the FDBs with high stability by reducing vibration for the UUV propulsor.