Heat Transfer and Thermoelastic Dynamics of a Rotating Flexible Disc in a Hard Disc Drive

摘要

Multi-field dynamic coupling takes place in computer hard disc drives, involving air flow, heat transfer and thermoelastic vibration of a rotating flexible disc in an enclosure filled with air. Air velocities and pressure induced by disc rotation in the enclosure are obtained by using penalty finite element method. Temperature increments in the rotating disc, driving shaft, enclosure and air flow are determined interactively by including the external heat sources from the shaft driving motor and enclosure circuit board, the internal heat source from aerodynamic heating due to viscous fluid dissipation, the heat convection in air flow, and the free convection heat loss at enclosure's outside surfaces. Natural frequencies of the rotating disc under the thermal stresses induced by the disc's temperature increment and centrifugal force are determined. Effects of air flow, heat convection and aerodynamic heating induced by disc rotation on heat balance in the enclosure and natural frequencies of the rotating flexible disc are investigated. This investigation is useful to hard drive design.