容器内の回転円盤に駆動される三次元流れにおける計測角度線上粒子検出による複雑挙動の理解に向けた基礎検討

抄録

We investigated complex motion of small particles in a rotating flow driven by a pair of corotating disks mounded in an enclosure equipped with a partial shrouhd opening. The flow is a model of hard disk drive (HDD) used for external storage device. In HDD, small particles discharged from mechanical parts levitats in the wokring fluid and they may cause damage on the disk and/or magnetic head. In the present study, flow visualization expetiments were performed to elucidate the complex motions of small particles in the highly unsteady and three-dimensional flow formed in a HDD model. Regractive index matched system was used for providing unobstracted view of the whole flow field. For particles, nearly neutrally buoyant particles were seeded into the flow. Particle trajectories were observed by tracking the individual particles and their two-dimensional motion was analyzed in the polar cooridnate in the plane parallel to the disks. As a result, particles tend to pass through certain positions in the plane. Initially, the levitating particles flow towards the outer region of the disks due to the centrifucal force, hit against the shrouded wall, and are reflected back into the inner region of the disk at certain circumferential angles. The statistical analysis revealed the trajectory tendency of particles passing through certain positions with higher frequencies compated to the other positions in the two dimensional plane.