FRACTIONAL-FREQUENCY ROTOR MOTION DUE TO NONSYMMETRIC CLEARANCE EFFECTS. Academic Article uri icon

abstract

  • ANALYSIS BASED ON THE JEFFCOTT MODEL IS PRESENTED TO EXPLAIN 1/2 SPEED AND 1/3 SPEED WHIRLING MOTION OCCURRING IN ROTORS WHICH ARE SUBJECT TO PERIODIC NORMAL-LOOSE OR NORMAL-TIGHTRADIAL STIFFNESS VARIATIONS. THE NORMAL-LOOSE STIFFNESS VARIATION RESULTS DUE TO BEARING-CLEARANCE EFFECTS, WHILE NORMAL-TIGHT STIFFNESS VARIATIONS RESULT FROM RUBBING OVER A PORTION OF A ROTOR'S ORBIT. THE RESULTS DEMONSTRATE THAT 1/2 SPEED SUBHARMONIC MOTION CAN BE EXPLAINED AS EITHER A LINEAR PARAMETRIC-EXCITATION PHENOMENON OR AS A STABLE NONLINEAR SUBHARMONIC MOTION. THE 1/3 SPEED MOTION IS SHOWN TO BE POSSIBLEDUE TO THE RADIAL STIFFNESS NONLINEARITY. A LINEAR PARAMETRIC-EXCITATION ANALYSIS DEMONSTRATES THAT DURING A NORMAL-TIGHT RUBBING CONDITION, COULUMB DAMPING SIGNIFICANTLY WIDENS THE POTENTIAL RANGE OF UNSTABLE SPEEDS.

author list (cited authors)

  • CHILDS, D. W.

publication date

  • January 1982