oil whirl and whip instabilities - within journal bearings

In the last few years research has demonstrated that the oil whirl occurs when the journal bearing operates with micropolar lubricant [6 7 8 9 10] For this reason the effect of the contamination of the lubricants [ 11 ] and of non-linear behaviour of film-oil journal bearings in rotating machines have been studied by many authors [ 12 ] Typically the whirl frequency is around 42% of the journal turning speed In extreme cases oil whirl leads to direct contact between the journal and the bearing which quickly wears out the bearing In some cases the frequency of the whirl coincides with and locks on to the critical speed of the machine shaft this condition is known as oil

Comparative assessment of physicochemical properties of

Jan 01 2011Mineral lubricating oils are derived from crude oil in the same process that produces gasoline kerosene and fuel oil they vary according to the type of crude oil and the refinery methods used [7] Modern motor engine oils are based upon oil refined from crude petroleum synthetic oil treated with various compounds or a mixture of one or two grades of mineral base oil

Oct 01 2011Berry James "Oil Whirl and Whip Instabilities within Journal Bearings " Machinery Lubrication magazine May-June 2005 Tribology Data Handbook Chapter 61 Journal Bearing Design and Analysis Khonsari M CRC Press 1997 Editor's Note:

An optional Oil Whirl/Whip kit can be ordered The Oil whirl kit consists of: Control DimensionsA high pressure oil pump assembly An oil whirl bearing assembly A rotor kit shaft with oil bearing journal A load frame Fluid-induced instabilities (both oil whirl and whip) as well as basic journal bearing behavior can be demonstrated using the

Most of the failures in oil-lubricated journal bearings are associated with mechanical instabilities produced by lubrication system problems or bearing wear and result in increased shaft vibration Therefore monitoring of the journal bearing condition in the field mainly relies on analysis of proximity probe or accelerometer signals However not all motors with journal bearings

The journal continues moving up as the rotative speed increases up to approximately 6000 rpm After the main instability threshold which occurs at 6750 rpm the journal centerline moves significantly to the bearing center as high amplitude oil whip vibrations develop

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frequency Journal bearings (which involve radial forces) are the normal location where these instabilities develop Orbit and frequency spectrum plots can be used to investigate the existence of whirl or whip vibrations From the theory of Complex Dynamic Stiffness the interaction among shaft oil film and bearing plays a major role in the

Hydrodynamic journal bearings are extensively used in turbomachinery due to their low wear rate and high load-carrying capacity [] However the interaction between the rotating system and the oil film of the journal bearing can cause unstable dynamic behavior characterized by sub-synchronous precessional motion called oil whirl [] The whirl frequency of this self-excited

Oct 13 2017Whirl vibrations are typically caused by fluid-structure interactions between the shaft and surrounding fluid media such as oil film between a shaft and journal in hydrodynamic journal bearings [] and drilling mud between a drilling string and borehole wall during an oil drilling process [] When the shaft receives a disturbing force such as a sudden surge of fluid

bearing enhances stability and can eliminate whirl and whip Thus externally pressurized bearings and seals offer a new approach to the control of fluid-induced instability In whirl the bearing stiffness is the weak stiffness of the system We can increase the pressure of an externally pressurized bearing increasing the bearing spring

journal bearing system is used for the parametric study An instabilities caused by fluid filin bearings seals and are functions of rotor speed oil sity bearing load and bearing clearance Other sources of self-excitation include the aerodynamic of impellers and seals

Rotor instabilities are associated to the operation speed and can have structural or dynamic sources from the shaft bearings and foundation or even from an actuator external force This work focuses on a strategy that uses the μ-synthesis control technique to attenuate the oil whip instability effect of flexible hydrodynamically supported

Note: Tilting pad journal bearings (often used on prop shaft bearings) do not suffer from whirl Oil Whip Oil whip occurs when the oil whirl frequency coincides with the rotating shafts natural frequency Resonance occurs and the amplitude of the vibration increases - limited to the bearing

In extreme cases oil whirl leads to direct contact between the journal and the bearing which quickly wears out the bearing In some cases the frequency of the whirl coincides with and locks on to the critical speed of the machine shaft this condition is known as oil whip Oil whip can be very destructive

Journal Bearing Failure Monitoring (JBFM)

J E Berry Oil whirl and whip instabilities – within journal bearings Technical Associates of Charlotte PC Machinery Lubrication Magazine (May 2005) Google Scholar Causes of Engine Bearing Failure copyright by Open image in new window Google Scholar

Hydrodynamic journal bearings induced serious shaft vibrations called oil whirl Since they often give severe damages to the mechanical systems it is important to fully understand the phenomenon to avoid the occurrence by the proper bearing design This study theoretically and experimentally investigated both cylindrical and conical whirl instabilities which can be appeared in journal

Aug 30 2014Fluid Induced Instabilities (oil whirl / oil whip) are a form of self-excited vibration where the inherent force balance within the bearing seal etc has been disrupted thus allowing the tangential force to push the rotor in a forward circular direction

However journal bearings are known to be prone to instabilities The oil whirl and oil whip instabilities limit the rotor maximum rotating speed In this paper a novel approach is used to control the journal bearing instability An active magnetic bearing (AMB) is used to overcome the JB instability and to increase its range of operation

frequency Journal bearings (which involve radial forces) are the normal location where these instabilities develop Orbit and frequency spectrum plots can be used to investigate the existence of whirl or whip vibrations From the theory of Complex Dynamic Stiffness the interaction among shaft oil film and bearing plays a major role in the