Eventos Anais de eventos
DINAME 2017
XVII International Symposium on Dynamic Problems of Mechanics
Instability Prediction and Rotordynamic with Seals: Simulations based on the Bulk-Flow Theory and Experimental Measurements
Submission Author:
Christian Wagner , na , Germany
Co-Authors:
Christian Wagner, Wataru Tsunoda, Tobias Berninger, Thomas Thümmel, Daniel Rixen
Presenter: Christian Wagner
doi://10.26678/ABCM.DINAME2017.DIN17-0047
Abstract
In high-speed rotational machinery such as pumps or compressors, contactless seals are commonly used to separate different fluids or gases and pressure levels. However, the presence of a leakage flow through the seal gap exerts forces on a moving, vibrating rotor. These can culminate in stiffening, restoring, and damping effects as well as in unstable, self-excited vibrational behavior. The JEFFCOTT rotor model and rotordynamic seal coefficients are put under investigation to prevent instability in the rotating machinery and to determine the rotor-seal system’s dynamic behavior. Two different methods are shown: an experimentally based one–on which this paper focuses–and a simulation-based one using simple, well known models of bulk-flow theory. The experimental method is examined on a flexible rotor-seal test rig using an active magnetic bearing for excitation. Coefficient identification problems due to unknown random force (noise) in the experimental case are shown and a solution is described in detail and validated on the test rig. Both methods lead to a calculation of rotordynamic seal coefficients during safe operating conditions. They are ultimately used to describe the system’s behavior and to predict the onset speed of instability using extrapolation techniques.
Keywords
Rotordynamics, Seals, instability, Self-excited vibration, Active magnetic bearing, seal coefficient measurement, Coefficient measurement
