VIBRATION DURING CENTRIFUCATION

摘要

Vibration is of concern in many experiments. For example, low-frequency acceleration influences buoyancy-driven convection. If there are two fluid phases present, vibration can cause oscillation of the interface between them, thereby pumping the adjacent fluids. High frequency vibrations can be transmitted through the container walls to cause streaming of the fluid and, in addition, move second-phase particles relative to the fluid. There are several sources of vibration in centrifuges. Here, we are concerned with the experiment package on large centrifuges operating in the open atmosphere. We offer as an example our experience on the Clarkson centrifuge HIRE. A tube furnace was placed in a box, 30.5 cm X 30.5 cm X 25.4 cm, that was attached by a hinge to the centrifuge arm so as to maintain the net acceleration vector approximately aligned with the axis of the furnace. A triaxial accelerometer was placed within this 20 kg package. The attachment hinge was 1.65 m from the center of rotation. At accelerations from 2 to 5 g , vibration was observed mainly at 17 Hz in the direction of rotation, with a maximum amplitude at 5 g. This was most likely due to periodic vortex shedding that became locked-in to the mechanical resonance frequency (17 Hz) of the system.