Dynamic Film Pressure Measurements in Journal Bearings for Use in Rotor Balancing

1976 ◽  
Vol 98 (1) ◽  
pp. 92-100 ◽  
Author(s):  
E. Christensen ◽  
J. Tonnesen ◽  
J. W. Lund
Keyword(s):  
Experimental Investigation ◽  
Measurement Accuracy ◽  
Journal Bearing ◽  
Linear Analysis ◽  
Journal Bearings ◽  
Experimental Measurements ◽  
Pressure Measurements ◽  
Pressure Transducers ◽  
Theoretical Predictions ◽  
Rotor Balancing

The paper presents the results of an experimental investigation where membrane transducers in the journal bearing wall are used to measure the dynamic oil-film pressures caused by rotor unbalance whirl. The results are applied successfully to balancing the rotor, and the experimental measurements of amplitude and pressure response are found to agree well with theoretical predictions, based on a linear analysis. The measurement accuracy of the pressure transducers compare favorably with the accuracy obtained with shaft displacement probes.

scholarly journals Observation of Pressure Variation in the Cavitation Region of Submerged Journal Bearings

1982 ◽  
Vol 104 (2) ◽  
pp. 157-163 ◽  
Author(s):  
I. Etsion ◽  
L. P. Ludwig
Keyword(s):  
Journal Bearing ◽  
Reverse Flow ◽  
Ambient Pressure ◽  
Journal Bearings ◽  
Pressure Variation ◽  
Pressure Measurements ◽  
Pressure Profiles ◽  
Cavitation Region ◽  
Cavitation Pressure ◽  
Visual Observations

Visual observations and pressure measurements in the cavitation zone of a submerged journal bearing are described. Tests were performed at various shaft speeds and ambient pressure levels. Some photographs of the cavitation region are presented showing strong reverse flow at the downstream end of the region. Pressure profiles are presented showing significant pressure variations inside the cavitation zone, contrary to common assumptions of constant cavitation pressure.

Asynchronous Instability of a Rotating Centrifuge Partially Filled With Fluid

1985 ◽  
Vol 52 (4) ◽  
pp. 777-782 ◽  
Author(s):  
C. A. Cheng ◽  
A. S. Berman ◽  
T. S. Lundgren
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Support System ◽  
Linear Analysis ◽  
Elastic Support ◽  
Mass Ratio ◽  
Stability Boundaries ◽  
Fill Ratio ◽  
Theoretical Predictions ◽  
The Stability

An experimental investigation of the asynchronous whirl motion of a partially filled rotating centrifuge on an elastic support system has been performed. Whirl runout amplitudes are measured and the data are used to deduce the stability boundaries of the asynchronous whirl. The effects of various parameters on the stability boundaries are studied systematically. These parameters are the fill ratio, mass ratio, Reynolds number, and the damping of the elastic support system. The experimental results are compared with theoretical predictions based on a linear analysis. Free surface shapes are compared with results of nonlinear analysis.

An Experimental Investigation on Friction Coefficient in Plain Journal Bearings During Start-Up

2008 ◽  
Author(s):  
J. Bouyer ◽  
M. Fillon
Keyword(s):  
Experimental Investigation ◽  
Friction Coefficient ◽  
Journal Bearings ◽  
Radial Clearance ◽  
Experimental Measurements ◽  
Air Bearings ◽  
Specific Pressure ◽  
Thrust Bearings ◽  
Start Up ◽  
Transient Thermal

The start-up friction coefficient is a parameter which is very useful for engineers who design hydrodynamic bearings. It is most often issued from an approximation. Several studies can be found in the literature on this topic but most of them are concerned with air bearings or are only numerical. Some studies are more general and deal with the transient thermal behaviour in journal bearings as well as in thrust bearings. Other studies deal with the friction coefficient during running, at a fixed rotational speed. The aim of this study is to provide experimental measurements of the bush torque during start-up of plain journal bearings, varying the specific pressure. Thus, the friction coefficient at start-up (deduced from measurements) is obtained for four different bearings varying feeding conditions, radial clearance and length.

A Theoretical and Experimental Investigation of a Gas Operated Bearing Damper for Turbomachinery: Part II — Experimental Results and Comparison With Theory

1993 ◽  
Author(s):  
Padmanabhan Sundararajan ◽  
John M. Vance
Keyword(s):  
Experimental Investigation ◽  
High Temperature ◽  
Theoretical Model ◽  
Natural Frequency ◽  
Experimental Results ◽  
Experimental Measurements ◽  
Vibration Damper ◽  
Theoretical Predictions ◽  
Present Design ◽  
Gas Damper

Abstract This is the second of two papers describing results of a research project directed at developing a gas operated vibration damper for high temperature turbomachinery applications. This part presents the experimental measurements made on three variations of the gas damper hardware and compares them with the theoretical predictions presented in Part I. It is found that the isentropic theoretical model predicts the damper characteristics quite well. A maximum damping of 13.2 Ib-s/in was measured for a single actuator at a natural frequency of 100 hz using the present design and the results suggest that significantly higher damping levels are possible with design modifications.

A Transient Thermoelastohydrodynamic Study of Steadily Loaded Plain Journal Bearings Using Finite Element Method Analysis

1999 ◽  
Vol 122 (1) ◽  
pp. 219-226 ◽  
Author(s):  
Bogdan-Radu Kucinschi ◽  
Michel Fillon ◽  
Jean Fre^ne ◽  
Mircea D. Pascovici
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Journal Bearing ◽  
Journal Bearings ◽  
The Finite Element Method ◽  
Thermal Boundary Conditions ◽  
Theoretical Predictions ◽  
Start Ups ◽  
Method Analysis ◽  
Element Method

The present paper proposes an advanced bidimensional model necessary to calculate the temperature field in a journal bearing submitted to both rapid and slow start-ups. The model takes into account realistic thermal boundary conditions at fluid film-solid interfaces. The thermoelastic deformations of both the journal and of the bush are also considered and a special attention is paid to the ruptured zone of the film. The Finite Element Method (with upwind techniques whenever necessary) is employed to solve the equations implied by the model. Finally, the theoretical predictions were validated by comparison with experimental data. [S0742-4787(00)02701-6]

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.

scholarly journals The Prediction of Liquid Film Journal Bearing Performance with a Consideration of Lubricant Film Reformation: Part 2: Experimental Results

1985 ◽  
Vol 199 (2) ◽  
pp. 103-111 ◽  
Author(s):  
D Dowson ◽  
C M Taylor ◽  
A A S Miranda
Keyword(s):  
Experimental Investigation ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Lubricant Film ◽  
Plain Bearing ◽  
Operating Characteristics ◽  
Design Data ◽  
Cavitation Region ◽  
Satisfactory Prediction ◽  
Theoretical Results

Analyses and design data for plain journal bearings rarely take into account the phenomenon of film reformation. The consideration of the re-establishment of the lubricant film after the cavitation region is difficult in a number of ways. The importance of allowing for reformation is, however, being increasingly recognized. This is particularly true as regards the satisfactory prediction of lubricant flowrate and the thermal operating characteristics of a bearing. The authors have previously implemented a cavitation algorithm to enable the cavitation region in a plain journal bearing to be located automatically and efficiently in a computer analysis. In Part I of the present paper theoretical results have been presented for the case of a plain bearing with a square-ended, axial groove located at the position of maximum film thickness. The second part of the paper gives details of an experimental investigation designed to establish the validity of the analysis.

Journal Bearing Lubrication and Design

1948 ◽  
Vol 158 (1) ◽  
pp. 250-254
Author(s):  
A. S. T. Thomson
Keyword(s):  
Experimental Investigation ◽  
Applied Load ◽  
Journal Bearing ◽  
Point Contact ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Experimental Results ◽  
Radial Clearance ◽  
Series Of Experiments ◽  
Loaded Side

The paper summarizes the results of an experimental investigation on the effects of variation in bearing width and radial clearance on the operating conditions of centrally loaded clearance journal bearings, the bearing arc being kept constant at 120 deg. The investigation, which was carried out prior to 1940, is complementary to an earlier paper by the author in which the effects of variations in bearing width and arc of embrace were investigated. The experimental results are compared with theoretical values modified by the relevant leakage coefficients. The measure of agreement obtained indicates that theoretical values so modified may be used with confidence in design. A short series of experiments is described; in these, high-point contact at starting and stopping is eliminated by supplying oil to a groove in the loaded side of the bearing at a pressure sufficiently great to overcome the applied load. The effect of a groove on the loaded side of the brass under various conditions of lubrication is investigated.

scholarly journals Experimental Estimation of Journal Bearing Stiffness for Damage Detection in Large Hydrogenerators

2017 ◽  
Vol 2017 ◽  
pp. 1-17 ◽  
Author(s):  
Geraldo Carvalho Brito ◽  
Roberto Dalledone Machado ◽  
Anselmo Chaves Neto
Keyword(s):  
Damage Detection ◽  
Journal Bearing ◽  
Turbine Rotor ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Tilting Pad ◽  
Theoretical Predictions ◽  
Bearing Stiffness ◽  
Stiffness And Damping

Based on experimental pieces of evidence collected in a set of twenty healthy large hydrogenerators, this article shows that the operating conditions of the tilting pad journal bearings of these machines may have unpredictable and significant changes. This behavior prevents the theoretical determination of bearing stiffness and damping coefficients with an adequate accuracy and makes damage detection difficult. Considering that dynamic coefficients have similar sensitivity to damage and considering that it is easier to monitor bearing stiffness than bearing damping, this article discusses a method to estimate experimentally the effective stiffness coefficients of hydrogenerators journal bearings, using only the usually monitored vibrations, with damage detection purposes. Validated using vibration signals synthesized by a simplified mathematical model that simulates the dynamic behavior of large hydrogenerators, the method was applied to a journal bearing of a 700 MW hydrogenerator, using two different excitations, the generator rotor unbalance and the vortices formed in the turbine rotor when this machine operates at partial loads. The experimental bearing stiffnesses obtained using both excitations were similar, but they were also much lower than the theoretical predictions. The article briefly discusses the causes of these discrepancies, the method’s uncertainties, and the possible improvements in its application.

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