A Solution for the Finite Journal Bearing and its Application to Analysis and Design: III

Raimondi, A. A.; Boyd, John

doi:10.1080/05698195808972330

Cited by 80 publications

(21 citation statements)

References 5 publications

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“…Though the experiments are mad e for th e bearing of LID = 1.0 -2.0, the resul ts agree well with the solutions with infinitely long bearing approximation rather th an with finite bearing assumption (5). Figure 12 is the exper imental results of film-rupture position versus Sommerf eld number .…”

Section: Discussionsupporting

confidence: 72%

On the Separation Boundary Condition for Fluid Lubrication Theories of Journal Bearings

Mori

Yabe

Fujita

1968

A S L E Transactions

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Various boundary conditions of fluid lubrication th eories have been presen ted for th e trailing edge of the lubricant film of a journal bearing, but th ey do not seem to be clearly investigated ph ysically in connec tion with the lubricant film rupture. Th e reverse flow and, hence, th e separation of fluid are observe d experi ment ally to cause the film ruptu re. This condition is brought to be the boundary condition of th e bearing film rup ture in this paper. By usin g this condi tion, the bearing characteristics, such as eccentricity, load capacity, and attitude angle, are investigated theoretically . Th e experimen tal results, obtain ed by using the transparent bearing for the direct observation of th e bearing film behavior, agree well with the theoretical ones.On the oth er hand, DuBois and Ocvirk (4) use th e infinitely short bearing approxima t ion, then the boundary condition in the axial direction is h = cr ( l + e cos 0) = film t hickness , c, = radial clearance, e = eccentricity ra tio .One of the a pproaches t o solve Eq.[1] is to neglect t he axi al flow t erm (the second t erm of the left side of Eq. [1]) compa ring it with the circumferent ial flow term assuming it to be an infinitely long journal bearing. Anot her is to neglect the cir cumferential flow term cont ra rily with infinitely short bearing approximati on.The bou ndary conditi on presented by Sommerfeld (l) is to ass ume a complete ly continuous lubricant film and , + '. " , " 2' }- [4] o= 71" + 00 { p = 0, ap = 0 a t ao p = 0 at 0 = 0 and 271". [2] The solution with t his cond it ion gives the sy mmet rical existe nce of positive and negative pressures, hence t he sha ft locus becomes t he st raight line of ep (attitude angle) = 90°. Gumbel (2) uses a boundary condition of p = 0 at 0 = 0, 71" an d 71"~0~271". [3] whi ch is to neglect t he neg ative pressure from Sommerfeld's solut ion, but there remains a discontinuity of flow ra te at 0 = 7['.The t hird boundary condit ion (3) assumes zero pressur e gradient at the t railing edge followed by the discontinuous region , namely a t. 0 = 0, 71" + 00 and

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Section: Discussionsupporting

confidence: 72%

On the Separation Boundary Condition for Fluid Lubrication Theories of Journal Bearings

Mori

Yabe

Fujita

1968

A S L E Transactions

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“…The work of Raimondi and Boyd (1958) can also be used to determine the attitude angle of the bearing during operation as a function of the Sommerfeld number. For the conditions of Figure 11, S=0.26, gives a value for the attitude angle of =46º.…”

Section: Measurement In the Cavitated Regionmentioning

confidence: 99%

“…The measurements reported here are recorded not at the minimum film point but rather at the maximum load point. The theoretical solution of Raimondi and Boyd [1958] has been used to predict the film thickness in this bearing both at the minimum film point and also at the maximum load point (i.e. the vertical position).…”

Section: Steady State Film Thickness Measurementsmentioning

confidence: 99%

A Method for the Measurement of Hydrodynamic Oil Films Using Ultrasonic Reflection

2004

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The measurement of the thickness of an oil film in a lubricated component is essential information for performance monitoring and control. In this work a new method for oil film thickness measurement, based on the reflection of ultrasound, is evaluated for use in fluid film journal bearing applications. An ultrasonic wave will be partially reflected when it strikes a thin layer between two solid media. The proportion of the wave reflected depends on the thickness of the layer and its acoustic properties. A simple quasi-static spring model shows how the reflection depends on the stiffness of the layer alone. This method has been first evaluated using flat plates separated by a film of oil, and then used in the measurement of oil films in a hydrodynamic journal bearing. A transducer is mounted on the outside of the journal and a pulse propagated through the shell. The pulse is reflected back at the oil film and received by the same transducer. The amplitude of the reflected wave is processed in the frequency domain. The spring model is then used to determine the oil film stiffness that can be readily converted to film thickness. Whilst the reflected amplitude of the wave is dependent on the frequency component, the measured film thickness is not; this indicates that the quasi-static assumption holds. Measurements of the lubricant film generated in a simple journal bearing have been taken over a range of loads and speeds. The results are compared with predictions from classical hydrodynamic lubrication theory. The technique has also been used to measure oil film thickness during transient loading events. The response time is rapid and film thickness variation due to step changes in load and oil feed pressure can be clearly observed.

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“…Bearing performance F or each bearing shape, A, B, C and D, determinations of the net dime nsio nless hori zontal and vertical loads were made for a series of attitude angles and eccentricity ratios, using Eq. [3][4][5][6] and Figs. 4 and 5.…”

Section: Geometric Relationshipsmentioning

confidence: 99%

Orthogonally Displaced Bearings — I

Wilcock

1961

A S L E Transactions

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Journal bearings with cross section s consisting of circular arcs wi th centers displaced from the geome tric bearing cent er alon g the mid-radius of the arc or lobe hav e been in use for many years. Examples are t he " elliptical" bearing and the " three-lobe" bearing, the advantage sought being increased stab ility under light loads witho·ut the reduced oil flow accompan yin g a reduced clearance ratio.Th is pap er is directed toward th e apparently neglected possibilit y of displacing th e lobe centers of two-lobe bearings orthogonally with respect to th e mid-radius of the lobe. Analysis show s that when th e lobe displacem ent is in a direction oppo site to th e shaft surface motion, as shown in Figs. 1 and 2, and th e bearing is centrally loaded, shaf t stiffness ortho gonal to th e load vector is substantially increased. At the same time , vertical stiffness remains essenticll y unchang ed. Minimum film thickn ess is decreased, parti cularly at low loads, while oil flow is increased. The analy sis was carried out for a bearing having in cross section two arcs each sub tending an an gle of 150°, an L ID ratio of 0 , and wi th th e arc cente rs each displaced from th e geom etric center by half the radial clearance. Nomenclature

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A Solution for the Finite Journal Bearing and its Application to Analysis and Design: III

Cited by 80 publications

References 5 publications

On the Separation Boundary Condition for Fluid Lubrication Theories of Journal Bearings

On the Separation Boundary Condition for Fluid Lubrication Theories of Journal Bearings

A Method for the Measurement of Hydrodynamic Oil Films Using Ultrasonic Reflection

Orthogonally Displaced Bearings — I

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