Contact analysis of a flexible bladed-rotor

Abstract

This paper presents a model of fully flexible bladed rotor developed in the rotating frame. An energetic method is used to obtain the matrix equations of the dynamic behaviour of the system. The gyroscopic effects as well as the spin softening effects and the centrifugal stiffening effects, taken into account through a pre-stressed potential, are included in the model. In the rotating frame, the eigenvalues' imaginary parts of the latter matrix equation give the Campbell diagram of the system and its stability can be analysed through its associated eigenvalues' real parts. The turbo machine casing is also modelled by an elastic ring in the rotating frame through an energetic method. Thus, the contact problem between the rotor and the stator can be treated as a static problem. Prior to the study of the complete problem of contact between the flexible blades of the rotor and the flexible casing, a simple model of an elastic ring having only one mode shape, excited by rotating loads is developed in the rotating frame too, in order to underline divergence instabilities and mode couplings. Then, the real complex problem of contact between the blades and the casing, without rubbing, is studied. The stable balanced static contact configurations of the structure are found as function of the rotational speed of the rotor. Finally, the results are compared to these of the simple model of rotating spring-masses on an elastic ring.

Untwisting the Campbell diagrams of weakly anisotropic rotor systems

“…1(f). This rather complicated behavior is difficult to predict and even to interpret as it was reported in the studies of numerous mechanical systems, see, e.g, [20,21,24,25,27,29,35,36,39,43,48]. The present work reveals that the untwisting of the Campbell diagrams is determined by a limited number of singular eigenvalue surfaces.…”

Bifurcation and chaos of the bladed overhang rotor system with squeeze film dampers

“…Genta [6] indicated that the vibration of blade may cause the instability of the bladed rotor system. Lesaffre et al [7] investigated the contact problem of the rotating blade against the stationary outer case in the bladed rotor system. They discussed the frictionless sliding contact between the blades and the casing, without rubbing, and highlighted an unstable phenomenon near the stator critical speed.…”

Response Characteristics of Looseness‐Rubbing Coupling Fault in Rotor‐Sliding Bearing System

“…In the role of oil film force, the system will show oil film instability phenomenon [21][22][23][24][25]. To clearly observe the dynamics characteristic of rotor system under the oil film force, then specially draw the threedimensional spectrum on the right neck (node 25) of the rotor system without fault, shown in Figure 5.…”