2023 年 10 巻 4 号 p. 22-00477
In a previous paper, a closed-loop mechanism represented by successive excitation processes was introduced to explain the reason for the nonlinearity-induced transition from unstable response to stable vibration. In one of the processes, the dynamic pressure is excited by the centrifugal force. Based on this, this paper investigates a vibration reduction method that introduces a circumferential flow whose velocity relative to the rotor is negative. This flow is predicted to weaken the excitation effect of the centrifugal force on the dynamic pressure. An improved semi-analytical model is developed for conservative estimate of the vibration reduction effect by considering the boundary condition that the relative flow velocity vanishes at the cylindrical wall. Because there arise circumferential flow velocity terms in various governing equations, the influences of the terms on the response are examined, thereby identifying important mechanism that contributes to the vibration reduction. The present semi-analytical method is helpful for this identification as well as computationally efficient analysis.
