Experiments on the Stability of an Overhung Rotor in Pressure-Dam and Multilobe Bearings

Four sets of bearings were tested on a three-mass overhung flexible rotor: axial-groove, pressure-dam, and two sets of preloaded (0.75 and 0.40) multilobe bearings. The first and second critical speeds were observed at 3200 and 6800 rpm; predicted values were 2960 and 7420, respectively. The instability thresholds were observed to depend strongly on the load orientations for the axial-groove and multilobe bearing. The maximum instability thresholds (optimum load direction for the axial-groove, multilobe (m = 0.75), and multilobe (m = 0.40) bearings were 6700 rpm, 9200 rpm, and 6800 rpm, respectively. For the pressure-dam bearings, it was 6400 rpm and was predicted to be 5800 rpm. The lowest instability threshold for the axial-groove and multilobe bearings were 5750 rpm, 7600 rpm, and 6200 rpm, respectively. When known unbalances were added to the rotor in the pressure-dam bearings, the stability threshold was increased to above the safe running range of the rotor and a brief instability was observed as th...

[1]  O. Pinkus.  Analysis and Characteristics of the Three-Lobe Bearing , 1959 .

[2]  L. E. Barrett,et al.  Experimental-Theoretical Comparison of Instability Onset Speeds for a Three Mass Rotor Supported by Step Journal Bearings , 1980 .

[3]  C. S. Lee,et al.  Stability of profile bore bearings: influence of bearing type selection , 1980 .

[4]  R. Flack,et al.  Effects of Three-Lobe Bearing Geometries on Flexible Rotor Stability , 1982 .

[5]  Paul E. Allaire,et al.  Analysis of Step Journal Bearings—Finite Length, Stability , 1980 .

[6]  R. Flack,et al.  Effects of Three-Lobe Bearing Geometries on Rigid-Rotor Stability , 1982 .

[7]  B. J. Hamrock,et al.  Rayleigh Step Journal Bearing, Part II—Incompressible Fluid , 1968 .

[8]  R. Flack,et al.  An Experimental and Theoretical Examination of the Static Characteristics of Three-Lobe Bearings , 1980 .

[9]  J. Glienicke,et al.  Paper 13: Experimental Investigation of the Stiffness and Damping Coefficients of Turbine Bearings and Their Application to Instability Prediction: , 1966 .

[10]  C. F. Kettleborough,et al.  An Approximate Analytical Solution for the Stepped Bearing , 1961 .

[11]  Ronald D. Flack,et al.  Experiments on the Stability and Response of a Flexible Rotor in Three Types of Journal Bearings , 1982 .

[12]  Fredrick T. Schuller.  Stability experiments with hydrodynamic tilted-lobe journal bearings of various numbers of lobes and length-to-diameter ratios , 1977 .

[13]  J. W. Lund,et al.  Stability and Damped Critical Speeds of a Flexible Rotor in Fluid-Film Bearings , 1974 .

[14]  Donald F. Wilcock,et al.  Bearing design and application , 1957 .

[15]  C. M. McC. Ettles,et al.  The Effect of Grooving and Bore Shape on the Stability of Journal Bearings , 1980 .

[16]  J. W. Lund,et al.  Some Experiments on Instability of Rotors Supported in Fluid-Film Bearings , 1978 .

[17]  Paul E. Allaire,et al.  Experimental Study of Three Journal Bearings with a Flexible Rotor , 1980 .