The Characteristics of Rotordynamic Forces generated by Mechanical Seals

Abstract

Evaluating rotordynamic reaction force caused by whirl excitation is very effective technique in order to investigate the dynamic properties of the mechanical seal. Especially, it is easy to understand the stability of the rotating component by investigating rotordynamic tangential force. In this paper, the stability of the mechanical seal was discussed by measuring the rotordynamic tangential force depending on the whirl frequency. Judging from the result, the mechanical seal used for this study has stable performance that the tangential force always acts against whirling direction at 1,000 rpm of rotational speed and up to 30 Hz of whirl frequency. Furthermore, whirl frequency ratio and effective damping were calculated using cross-coupled stiffness and direct damping which were obtained by solving quaternary linear equations after whirl excitation test. Whirl frequency ratio was always bellow 1.0, and effective damping was also always positive at all frequencies. Those results indicate that the mechanical seal definitely generate the force to stabilize this whirl vibration.