Investigation of Whirl in Externally Pressurized Air-Lubricated Journal Bearings

1962 ◽  
Vol 84 (1) ◽  
pp. 132-138 ◽  
Author(s):  
W. A. Gross
Keyword(s):  
Experimental Investigation ◽  
Critical Frequency ◽  
Rotational Frequency ◽  
Journal Bearings ◽  
Rigid Rotor ◽  
First Order ◽  
Supply Pressure ◽  
Mass Unbalance ◽  
Prediction Techniques ◽  
Special Case

The nature of whirl of a rigid rotor in externally pressurized air-lubricated journal bearings, including self-acting bearings as a special case, is discussed and an experimental investigation described. Rotor unbalance leads to synchronous whirl which can persist through one or more critical speeds. Self-excited whirl is likely when the rotational frequency is about twice the lowest critical frequency. We discuss the effects of supply pressure, number and location of sources, rotational speed, mass, unbalance, and load upon the onset of self-excited whirl, and describe first-order prediction techniques.

Analysis of Pneumatic Instability of Externally Pressurized Porous Gas Journal Bearings

1979 ◽  
Vol 101 (1) ◽  
pp. 48-53 ◽  
Author(s):  
N. S. Rao ◽  
B. C. Majumdar
Keyword(s):  
Theoretical Analysis ◽  
Mass Parameter ◽  
Journal Bearings ◽  
Order Perturbation ◽  
Rigid Rotor ◽  
Eccentricity Ratio ◽  
Dynamic Displacement ◽  
First Order ◽  
Supply Pressure ◽  
First Order Perturbation

A theoretical analysis is presented for the study of pneumatic instability for a rigid rotor supported in externally pressurized porous gas journal bearings. The analysis is based on a first-order perturbation with respect to the amplitude of dynamic displacement of rotor. The variation of threshold mass parameter with feeding parameter is shown. In addition, the effects of supply pressure, eccentricity ratio, L/D ratio, and porosity parameter are investigated and presented in the form of graphs.

A Theoretical Analysis of Whirl Instability and Pneumatic Hammer for a Rigid Rotor in Pressurized Gas Journal Bearings

1967 ◽  
Vol 89 (2) ◽  
pp. 154-165 ◽  
Author(s):  
J. W. Lund
Keyword(s):  
Theoretical Analysis ◽  
Time Constant ◽  
Pressure Ratio ◽  
Journal Bearings ◽  
Restricted Feeding ◽  
Rigid Rotor ◽  
Eccentricity Ratio ◽  
Pneumatic Hammer ◽  
Small Eccentricity ◽  
First Order

A theoretical analysis is presented for the threshold of instability for a rigid rotor supported in hydrostatic gas journal bearings. Both rotationally induced instability (hybrid instability) and pneumatic hammer are considered. The analysis is based on a first-order perturbation with respect to the eccentricity ratio (i.e., the results are limited to small eccentricity ratios) and makes use of the linearized Ph-method [2, 5, 8]. The pressurized gas is supplied to the bearing through restricted feeding holes in the center plane of the bearing and the analysis takes into account the discreteness of the feeding holes, the feeder hole time constant, and inherent compensation effects. Numerical results are given in form of 16 graphs, showing the threshold of instability as a function of supply pressure ratio, feeding parameter and eccentricity ratio. Also, the effect of the feeder hole time constant is investigated with respect to pneumatic hammer.

The Influence of Oil Supply Pressure on the Behavior of a Rigid Symmetrical Balanced Rotor in Journal Bearings With Circumferential Feeding

1992 ◽  
Vol 114 (4) ◽  
pp. 812-817 ◽  
Author(s):  
G. Capone ◽  
M. Russo ◽  
R. Russo
Keyword(s):  
Experimental Investigation ◽  
Journal Bearings ◽  
Experimental Results ◽  
Specific Load ◽  
Static Characteristics ◽  
Supply Pressure ◽  
Film Instability ◽  
Low Load ◽  
Theoretical Predictions ◽  
Load Conditions

A theoretical-experimental investigation was carried out on the behavior of a rigid symmetrical balanced rotor in short, cylindrical, circumferentially fed journal bearings under low load conditions. The influence of supply pressure on bearing static characteristics and oil film instability threshold was evaluated for the above system. The experimental results are shown along with the theoretical predictions of the static characteristics and limit stability curves for different values of the ratio between supply pressure and specific load.

Theoretical Analysis of Pneumatic Instability of Externally Pressurized Porous Gas Journal Bearings Considering Velocity Slip

1988 ◽  
Vol 110 (4) ◽  
pp. 730-733 ◽  
Author(s):  
M. C. Majumder ◽  
B. C. Majumdar
Keyword(s):  
Perturbation Theory ◽  
Theoretical Analysis ◽  
Mass Parameter ◽  
Velocity Slip ◽  
Journal Bearings ◽  
Order Perturbation ◽  
Rigid Rotor ◽  
First Order ◽  
First Order Perturbation

An analysis based on first-order perturbation theory is presented for the determination of pneumatic instability of a rigid rotor supported on externally pressurized porous gas journal bearings considering velocity slip. The variation of threshold mass parameter with feeding parameter for various supply pressures and L/D ratios under slip and no slip conditions is shown. It has been observed that there is a little decrease in stability when slip is taken in the analysis.

Oil Whirl of a Rigid Rotor in 360° Journal Bearings: Further Characteristics

1965 ◽  
Vol 180 (1) ◽  
pp. 593-610 ◽  
Author(s):  
J. R. Mitchell ◽  
R. Holmes ◽  
J. Byrne
Keyword(s):  
Experimental Investigation ◽  
Journal Bearings ◽  
Rigid Rotor ◽  
Oil Whirl ◽  
Experimental Findings

In an earlier paper (1)† the oil whirl of a rigid rotor was considered theoretically and compared with limited experimental findings. In this paper the comparison is taken further as a result of a fuller theoretical and experimental investigation.

Relativized realizability in intuitionistic arithmetic of all finite types

1978 ◽  
Vol 43 (1) ◽  
pp. 23-44 ◽  
Author(s):  
Nicolas D. Goodman
Keyword(s):  
Extension Theorem ◽  
General Notion ◽  
Conservative Extension ◽  
First Order ◽  
New Information ◽  
Reflection Theorem ◽  
Order Arithmetic ◽  
Special Case ◽  
Dependent Choice ◽  
Intuitionistic Arithmetic

In this paper we introduce a new notion of realizability for intuitionistic arithmetic in all finite types. The notion seems to us to capture some of the intuition underlying both the recursive realizability of Kjeene [5] and the semantics of Kripke [7]. After some preliminaries of a syntactic and recursion-theoretic character in §1, we motivate and define our notion of realizability in §2. In §3 we prove a soundness theorem, and in §4 we apply that theorem to obtain new information about provability in some extensions of intuitionistic arithmetic in all finite types. In §5 we consider a special case of our general notion and prove a kind of reflection theorem for it. Finally, in §6, we consider a formalized version of our realizability notion and use it to give a new proof of the conservative extension theorem discussed in Goodman and Myhill [4] and proved in our [3]. (Apparently, a form of this result is also proved in Mine [13]. We have not seen this paper, but are relying on [12].) As a corollary, we obtain the following somewhat strengthened result: Let Σ be any extension of first-order intuitionistic arithmetic (HA) formalized in the language of HA. Let Σω be the theory obtained from Σ by adding functionals of finite type with intuitionistic logic, intensional identity, and axioms of choice and dependent choice at all types. Then Σω is a conservative extension of Σ. An interesting example of this theorem is obtained by taking Σ to be classical first-order arithmetic.

Machine learning-based performance analysis of two-axial-groove hydrodynamic journal bearings

2021 ◽  
pp. 135065012199289
Author(s):  
Biswajit Roy ◽  
Sudip Dey
Keyword(s):  
Journal Bearing ◽  
Journal Bearings ◽  
Hydrodynamic Performance ◽  
Support Vector ◽  
Oil Viscosity ◽  
Hydrodynamic Analysis ◽  
Supply Pressure ◽  
Input Parameters ◽  
Precise Prediction ◽  
Output Behavior

The precise prediction of a rotor against instability is needed for avoiding the degradation or failure of the system’s performance due to the parametric variabilities of a bearing system. In general, the design of the journal bearing is framed based on the deterministic theoretical analysis. To map the precise prediction of hydrodynamic performance, it is needed to include the uncertain effect of input parameters on the output behavior of the journal bearing. This paper presents the uncertain hydrodynamic analysis of a two-axial-groove journal bearing including randomness in bearing oil viscosity and supply pressure. To simulate the uncertainty in the input parameters, the Monte Carlo simulation is carried out. A support vector machine is employed as a metamodel to increase the computational efficiency. Both individual and compound effects of uncertainties in the input parameters are studied to quantify their effect on the steady-state and dynamic characteristics of the bearing.

Experimental Investigation on Cavitation Characteristics of a Three-Groove Journal Bearing

2013 ◽  
Vol 420 ◽  
pp. 47-50
Author(s):  
Ying Yang ◽  
Jing Hua Dai
Keyword(s):  
Experimental Investigation ◽  
High Speed ◽  
Journal Bearing ◽  
Rupture Zone ◽  
Work Characteristics ◽  
Oil Film ◽  
Rotating Speed ◽  
Clear Effect ◽  
Supply Pressure

Under high and super-high speed, oil film of the journal bearing is easy to crack and then becomes cavitation. The existence of cavitation has an important effect on the work characteristics of the shaft. On the journal bearing experiment rig the cavitation characteristics of the three-groove journal beaing were studied. The influences of the shaft rotating speed and supply pressure on cavitation shape were investigated. The results show that rotating speed and supply pressure have a clear effect on the cavitation shape, and the number of cavitation strip in the rupture zone decreases when the supply pressure increases.

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