Vibration Analysis of Large High-Speed Rotating Equipment

This paper discusses the application of mobility methods to the lateral vibration analysis of coupled machinery. Some effects of bearing and/or casing structural mobility on the rotational system behavior are shown. In particular, the various types of system behavior and their interrelations are shown to be closely tied to the response of the rotor-support structure. The effect of hydrodynamic oil films are also shown. Lateral vibrational problems have been encountered when connecting drive and driven equipment produced by different manufacturers. Generally, these are caused by natural frequencies in the operating-speed range which result directly from the method of coupling. Methods of solving this problem are presented with emphasis on flexible couplings and their proper inclusion in system response calculations.