An Augmented, Small-Parameter Equation for the Squeeze-Film Journal Bearing

1970 ◽  
Vol 92 (3) ◽  
pp. 442-449 ◽  
Author(s):  
C. L. Strodtman
Keyword(s):  
Small Parameter ◽  
Shape Factor ◽  
Radial Displacement ◽  
Journal Bearing ◽  
Numerical Procedure ◽  
Squeeze Film ◽  
Mean Square ◽  
Root Mean Square Amplitude ◽  
Parameter Equation ◽  
Good Agreement

The asymptotic gas film equation for the squeeze-film journal bearing is solved for the quadratic and cubic terms in the series expansion in terms of the radial displacement. The load support calculated from this augmented, small parameter equation is compared to calculations from an all numerical procedure. Good agreement is shown to exist for large values of the radial displacement. A method of treating nonuniform excursion of the driving member by a root-mean-square amplitude and a shape factor is also given.

Optimization of Clearance in a Squeeze-Film Journal Bearing

1971 ◽  
Vol 93 (2) ◽  
pp. 246-251
Author(s):  
C. L. Strodtman
Keyword(s):  
Numerical Methods ◽  
Small Parameter ◽  
Shape Factor ◽  
Journal Bearing ◽  
Diameter Ratio ◽  
Parameter Analysis ◽  
Squeeze Film ◽  
Clearance Ratio ◽  
Proper Selection ◽  
Selection Of

It is shown that a squeeze-film journal bearing supporting a mass completely contained within the bearing can be designed with the optimum value of minimum clearance by proper selection of the drive amplitude to nominal clearance ratio, the length to diameter ratio, and the shape factor of the excursion. Both a small parameter and an augmented, small parameter analysis are given. In the latter case, numerical methods are employed to solve the resulting equations. The results of the analysis are illustrated in application to an accelerometer design.

scholarly journals On Error Torques of Squeeze-Film Cylindrical Journal Bearings

1968 ◽  
Vol 90 (1) ◽  
pp. 191-198
Author(s):  
C. H. T. Pan ◽  
T. Chiang
Keyword(s):  
Radial Displacement ◽  
High Performance ◽  
Journal Bearing ◽  
Rotational Symmetry ◽  
Mathematical Problem ◽  
Journal Bearings ◽  
Squeeze Film

The squeeze-film bearing has been considered for the output axis of high performance gyroscopes. Viewing this application, it is important that the parasitic torque of the bearing be very small. In the case of a squeeze-film journal bearing, parasitic torque can result from tolerance effects which disrupt rotational symmetry of the bearing. This problem has been studied by assuming ellipses for the tolerances of the journal and bearing surfaces as well as the squeeze motion, respectively. Each tolerance effect is assumed to be axially uniform. The mathematical problem is linearized with respect to each of the tolerances and the radial displacement of the journal. It was found that the parasitic torques do not depend on the radial displacement of the journal. The parasitic torques result from interactions among the three types of tolerance effects while each of the tolerances alone will not lead to any torque. Numerical estimates based on the geometry of a typical gyroscope and current fabrication practice shows such parasitic torques can seriously impair the accuracy of the gyroscope.

Load Support of the Squeeze-Film Journal Bearing of Finite Length

1968 ◽  
Vol 90 (1) ◽  
pp. 157-161 ◽  
Author(s):  
J. V. Beck ◽  
C. L. Strodtman
Keyword(s):  
Finite Difference ◽  
Small Parameter ◽  
Pressure Distribution ◽  
Journal Bearing ◽  
Unit Area ◽  
Parameter Analysis ◽  
Squeeze Film ◽  
Axial Pressure ◽  
Finite Difference Technique ◽  
Additive Term

Despite intuition, the squeeze-film bearing of finite dimensions produces much more load support per unit area than is found from a solution based on an infinite bearing. The load support is shown to be made up of two components—that due to the infinite journal plus an additive term due to the axial pressure distribution. Two methods of solution of the governing equation are applied: (a) A small-parameter analysis and (b) a numerical finite-difference technique. In the limit, the infinitely short journal is shown to have a load support 2.5 times that of the infinitely long journal.

Vibrational amplitudes for thionyl tetrafluoride and sulphur tetrafluoride

1965 ◽  
Vol 18 (10) ◽  
pp. 1575 ◽  
Author(s):  
MGK Pillai ◽  
K Ramaswamy ◽  
R Pichai
Keyword(s):  
Electron Diffraction ◽  
Oxygen Atom ◽  
Force Constant ◽  
Spectroscopic Data ◽  
Lone Pair ◽  
Electron Diffraction Data ◽  
Mean Square ◽  
Root Mean Square Amplitude ◽  
Energy Constants ◽  
Good Agreement

The potential energy constants and vibrational mean amplitudes for thionyl tetrafluoride were calculated using the Urey-Bradley Force Field (UBFF) with a view to finding out the influence of the oxygen atom on the SF4 group. It was found that the axial S-F stretching force constant is smaller than the equatorial S-F stretching force constant, which is consistent with the variation in the bond length. The behaviour of the oxygen atom is found to be similar to the lone pair of electrons in sulphur tetrafluoride. The vibrational mean amplitudes calculated from spectroscopic data are in very good agreement with the electron diffraction data. The large root mean square amplitude of vibration for equatorial-equatorial non-bonded fluorine atoms (0.099 Ǻ) in sulphur tetrafluoride indicates the possibility of incomplete inversion as pointed out by Chantry and Ewing.

scholarly journals Study on the Leakage and Inter-Stage Pressure Drop Characteristics of Two-Stage Finger Seal

2021 ◽  
Vol 11 (5) ◽  
pp. 2239
Author(s):  
Hailin Zhao ◽  
Hua Su ◽  
Guoding Chen ◽  
Yanchao Zhang
Keyword(s):  
Pressure Drop ◽  
Pressure Difference ◽  
Radial Displacement ◽  
Mean Square ◽  
The Finite Element Method ◽  
Axial Pressure ◽  
Two Stage ◽  
One Stage ◽  
The One ◽  
Lower Contact

To solve the high leakage and high wear problems faced by sealing devices in aeroengines under the condition of high axial pressure difference, the two-stage finger seal is proposed in this paper. The finite element method and computational fluid dynamics (FEM/CFD) coupling iterative algorithm of the two-stage finger seal is developed and validated. Then the performance advantages of two-stage finger seal compared to the one-stage finger seal are studied, as well as the leakage and the inter-stage pressure drop characteristics of two-stage finger seal are investigated. Finally, the measure to improve the inter-stage imbalance of pressure drop of two-stage finger seal is proposed. The results show that the two-stage finger seal has lower leakage and lower contact pressure than the one-stage finger seal at high axial pressure difference, but there exists an inter-stage imbalance of pressure drop. Increasing the axial pressure difference and the root mean square (RMS) roughness of finger element can aggravate the imbalance of pressure drop, while the radial displacement excitation of rotor has little influence on it. The results also indicate that the inter-stage imbalance of pressure drop of the two-stage finger seal can be improved by increasing the number of finger elements of the 1st finger seal and decreasing the number of finger elements of the 2nd finger seal.

Numerical investigation of dynamic and hydrodynamic characteristics of the pad in the fluid pivot journal bearing

2021 ◽  
pp. 135065012110330
Author(s):  
Tuyen Vu Nguyen ◽  
Weiguang Li
Keyword(s):  
Computational Models ◽  
Journal Bearing ◽  
Squeeze Film ◽  
Hydrodynamic Characteristics ◽  
Hydrodynamic Properties ◽  
Squeeze Film Damper ◽  
Lubricant Oil ◽  
Oil Flow ◽  
Flow Through ◽  
Bearing System

The dynamic and hydrodynamic properties of the pad in the fluid pivot journal bearing are investigated in this paper. Preload coefficients, recess area, and size gap, which were selected as input parameters to investigate, are important parameters of fluid pivot journal bearing. The pad’s pendulum angle, lubricant oil flow through the gap, and recess pressure which characterizes the squeeze film damper were investigated with different preload coefficients, recess area, and gap sizes. The computational models were established and numerical methods were used to determine the equilibrium position of the shaft-bearing system. Since then, the pendulum angle of the pad, liquid flow, and recess pressure were determined by different eccentricities.

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