The equations for a flexible rotor in journal bearings are set up and solved, extending the method previously used by Hummel and Cameron. It is shown that if w is the natural elastic frequency of the rotor, A the resonant oil frequency for an infinitely stiff but otherwise identical rotor, then the combined frequency s is given by l/s2 = 1/Λ2 + 1/w2. This resonant frequency will usually occur when it equals 1/2 the shaft rotational frequency
The frequency calculated by the method given here is applied to a number of cases of large turbines and alternators and found to give quite satisfactory results
Get full access to this article
View all access options for this article.
References
1.
HaggA. C.1946J. appl. Mech., Trans. Amer. Soc. mech. Engrs, vol. 68, p. 211, ‘The influence of oil film journal bearings on the stability of rotating machines’.
2.
PoritskyH.1953Trans. Amer. Soc. mech. Engrs, vol. 75, p. 1153, ‘Contribution to the theory of oil whip’.
3.
BoekerG. F.SternlichtB.1956ibid., vol. 78, p. 13, ‘Investigation of translatory fluid whirl in vertical machines’.
4.
BishopR. E. D.GladwellG. M. L.1959J. mech. Engng Sci., vol. 1, No. 1, p. 66, ‘Vibration and balancing of an unbalanced flexible rotor’.
5.
HummelC.1926Forschungsh. Ver. dtsch. Ing.287, ‘Kritische Drehzahlen als Folge der Nachgiebigkeit des Schmiermittels im Lager’.
6.
CameronA.1955Engineering, Lond., vol. 179, p. 237, ‘Oil whirl in bearings’.
7.
CameronA.SolomonP. J. B.1957Proc. Conf. Lubrication and Wear, Paper 103, p. 191, ‘Vibrations in journal bearings: preliminary observations’ (Instn Mech. Engrs, London).
OcvirkF. W.1952Tech. Note nat. adv. Comm. Aero., Wash., No. 2808, ‘Short-bearing approximation for full journal bearings’.
11.
CameronA.WoodW. L.1949Proc. Instn mech. Engrs, Lond., vol. 161, p. 59, ‘The full journal bearing’.
12.
BoydJ.RaimondiA. A.1958Lub. Sci. Techn. (Trans. Amer. Soc. lub. Engrs), vol. 1, p. 194, ‘A solution for the finite journal bearing and its application to analysis and design’.
13.
HolmesR.1960J. mech. Engng Sci., vol. 2, p. 337, ‘The vibration of a rigid shaft on short sleeve bearings’.
14.
MorrisonD.1962Proc. Instn mech. Engrs, Lond., vol. 176, No. 22, ‘The influence of plain journal bearings on the whirling action of an elastic rotor’.
15.
HoriYukio1959J. appl. Mech., Trans. Amer. Soc. mech. Engrs, Series E, vol. 81, p. 189, ‘A theory of oil whip’.
