Dynamic interaction of heat transfer, air flow and disc vibration of disc drives - Theoretical development and numerical analysis

Steady state air flow, heat transfer and thermoelastic dynamics in the multi-field coupling system of a rotating flexible disc in an enclosure filled with air are investigated within a large speed range. The system represents rotating discs in hard disc drives and optical disc drives. With Navier-Stokes and continuity equations and an improved penalty finite element method, air velocities and pressure induced by disc rotation in the enclosure are obtained. Temperature distribution of the rotating disc, driving shaft, enclosure and air flow is determined under the external heat sources from the shaft-driving motor and the circuit board inside the enclosure, the internal heat source from aerodynamic heating due to viscous dissipation of fluid, the heat convection in air flow, and the free convection heat loss at the enclosure׳s outside surfaces. Natural frequencies of the rotating disc are solved under the stresses induced by the disc temperature distribution and centrifugal force. Effects of heat convection and aerodynamic heating induced by disc rotation on system heat balance and dynamic characteristics of the rotating disc are investigated. The method presented is helpful to design of hard/optical disc drives and many other applications that involve rotating discs in fluids and with heat transfer.