Experimental Rotor Unbalance Response Using Hydrostatic Gas Lubrication

1973 ◽  
Vol 95 (4) ◽  
pp. 469-476 ◽  
Author(s):  
R. D. Dayton ◽  
M. R. Chasman
Keyword(s):  
Theoretical Model ◽  
Reasonable Agreement ◽  
Journal Bearings ◽  
Rotor Speed ◽  
Supply Pressure ◽  
Unbalance Response ◽  
Gas Lubrication ◽  
Theoretical Predictions ◽  
Theoretical Results

This paper investigates the adequacy of the theoretical model in predicting the unbalance response of a rotor supported in hydrostatic gas-lubricated journal bearings. The magnitude of experimental whirl amplitudes induced by applying various unbalances to a rotor supported in hydrostatic journal bearings were measured and compared to the theoretical predictions. Variables investigated were rotor unbalance, rotor speed, and bearing supply pressure. Reasonable agreement between the experimental and theoretical results was obtained.

Experimental Rotor Unbalance Response Using Hydrodynamic Gas Lubrication

1972 ◽  
Vol 94 (1) ◽  
pp. 74-80
Author(s):  
R. D. Dayton ◽  
M. R. Chasman
Keyword(s):  
Theoretical Model ◽  
Reasonable Agreement ◽  
Journal Bearings ◽  
Rotor Speed ◽  
Unbalance Response ◽  
Bearing Load ◽  
Gas Lubrication ◽  
Theoretical Predictions ◽  
Theoretical Results

This paper investigates the adequacy of the theoretical model in predicting the unbalance response of a rotor supported in hydrodynamic gas lubricated journal bearings. The magnitude of experimental whirl amplitudes induced by applying various unbalances to a rotor supported in hydrodynamic journal bearings were measured and compared to the theoretical predictions. Variables investigated were rotor unbalance, rotor speed, and bearing load. Reasonable agreement between the experimental and theoretical results was obtained.

Unbalance Response of a Dual Rotor System: Theory and Experiment

1993 ◽  
Vol 115 (4) ◽  
pp. 427-435 ◽  
Author(s):  
K. Gupta ◽  
K. D. Gupta ◽  
K. Athre
Keyword(s):  
System Theory ◽  
Transfer Matrix ◽  
Mode Shape ◽  
Reasonable Agreement ◽  
Complex Variables ◽  
Rotor System ◽  
Experimental Results ◽  
Unbalance Response ◽  
Theoretical Results ◽  
Theory And Experiment

A dual rotor rig is developed and is briefly discussed. The rig is capable of simulating dynamically the two spool aeroengine, though it does not physically resemble the actual aeroengine configuration. Critical speeds, mode shape, and unbalance response are determined experimentally. An extended transfer matrix procedure in complex variables is developed for obtaining unbalance response of dual rotor system. Experimental results obtained are compared with theoretical results and are found to be in reasonable agreement.

Thermal Behavior and Friction in Journal Bearings

1970 ◽  
Vol 92 (3) ◽  
pp. 373-380 ◽  
Author(s):  
Al. Nica
Keyword(s):  
Experimental Data ◽  
Thermal Behavior ◽  
Heat Dissipation ◽  
Journal Bearings ◽  
Friction Torque ◽  
Operating Characteristics ◽  
Lubricant Flow ◽  
Theoretical Predictions ◽  
Theoretical Results ◽  
Good Agreement

This paper deals with friction and the field of temperature in the lubricant film of journal bearings. Theoretical results regarding the thermal behavior are checked with experimental data and good agreement is found. Emphasis is put on the variation of temperature and lubricant flow with the operating characteristics of the bearing and it is seen that theoretical predictions for minima of friction torque are backed by temperature measurements. Further on, the friction torque and the mechanism of heat dissipation in bearings are dealt with, in order to verify the assumptions used in the calculation schemes. The means of efficiently cooling the bearing are also discussed, as well as the part played by the divergent zone in this process.

Theoretical and experimental investigation of the function of the wall flow deflecting ring. A single ring

1985 ◽  
Vol 50 (12) ◽  
pp. 2685-2696 ◽  
Author(s):  
Vladimír Staněk ◽  
Krumm Semkov ◽  
Nikolai Kolev ◽  
Georgii Paskalev
Keyword(s):  
Experimental Investigation ◽  
Theoretical Model ◽  
Reasonable Agreement ◽  
Experimental Results ◽  
Single Ring ◽  
The Future ◽  
Wall Flow ◽  
Trickle Bed ◽  
Theoretical Results

Theoretical model has been formulated of the flow of liquid in a randomly packed trickle bed column equipped with special wall flow deflecting rings (WFDR). Solutions have been obtained of the model for the case of a single ring. Theoretical results have been compared with experimental distributions of liquid in a 188.6 mm in diameter column packed with 25 mm Raschig rings and equipped with a single WFDR. Reasonable agreement of the theory with experimental results has been found and the theory is felt to be important in the future for optimizations of the number, size and spacing of the WFDR's to be used in industrial columns to check the extent of the flow on the wall.

A Comparison of Experimental Results and Theoretical Predictions for the Rotordynamic Coefficients of Short (L/D = 1/6) Labyrinth Seals

1991 ◽  
Author(s):  
Joseph M. Pelletti ◽  
Dara W. Childs
Keyword(s):  
Flow Model ◽  
Control Volume ◽  
Pressure Ratio ◽  
Experimental Results ◽  
Rotor Speed ◽  
Labyrinth Seals ◽  
Rotordynamic Coefficients ◽  
Supply Pressure ◽  
Test Conditions ◽  
Theoretical Predictions

Abstract Experimental results for the rotordynamic coefficients of short (L/D = 1/6) teeth-on-stator and teeth-on-rotor labyrinth seals are presented. The effects that pressure ratio (fluid density), rotor speed, fluid pre-swirl and seal clearance have on these coefficients are studied. Tests were run out to speeds of 16000 rpm with a supply pressure of 17.3 bar and seal clearances ranging from 0.229–0.419 mm. The experimental results are compared with theoretical predictions of a two control volume compressible flow model. The experimental results show that decreases in pressure ratio and increases in rotor speed are stabilizing while increases in fluid pre-swirl and seal clearance are destabilizing for both seal configurations. The theoretical model correctly predicts the effects of pressure ratio, rotor speed and fluid pre-swirl on the cross-coupled stiffness. It also predicts reasonable values for direct damping for all test conditions. However, the theory incorrectly predicts the effect of seal clearance on these coefficients. Consequently the theoretical predictions are much better for the large clearance seals.

Step Response Characteristics of Hydrostatic Journal Bearings With Self-Controlled Restrictors Employing a Floating Disk

1999 ◽  
Vol 121 (2) ◽  
pp. 315-320 ◽  
Author(s):  
S. Yoshimoto ◽  
K. Kikuchi
Keyword(s):  
Static Load ◽  
Journal Bearings ◽  
Step Response ◽  
Design Parameters ◽  
Static Stiffness ◽  
Load Direction ◽  
Response Characteristics ◽  
Theoretical Predictions ◽  
Theoretical Results ◽  
Very High

This paper describes the step response characteristics of hydrostatic journal bearings with self-controlled restrictors employing a floating disk. This type of bearing can achieve very high static stiffness by controlling the mass flow rate of the fluid entering the bearing clearance using a floating disk. Many design parameters such as supply pressure, viscosity, the magnitude of the step load and the imposed static load affect the step response characteristics of the proposed bearing. Therefore, the influences of each design parameter on the step response characteristics are theoretically investigated in this paper. Furthermore, the theoretical results are compared with the experimental results in order to verify the theoretical predictions. It is subsequently found that the proposed bearing consistently shows a stable step response irrespective of the step-load direction.

scholarly journals The Prediction of Liquid Film Journal Bearing Performance with a Consideration of Lubricant Film Reformation: Part 1: Theoretical Results

1985 ◽  
Vol 199 (2) ◽  
pp. 95-102 ◽  
Author(s):  
D Dowson ◽  
C M Taylor ◽  
A A S Miranda
Keyword(s):  
Liquid Film ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Lubricant Film ◽  
Supply Rate ◽  
Film Rupture ◽  
Supply Pressure ◽  
Wide Range ◽  
The Reformation ◽  
Theoretical Results

Analyses of liquid film journal bearings rarely consider the reformation of the lubricant film. This reformation normally takes place in the vicinity of a supply groove and is influenced by, amongst other parameters, the lubricant supply pressure. In a previous paper the authors have described in detail the implementation of an algorithm to locate automatically and efficiently the locus of film rupture and reformation boundaries using a digital computer. In the present paper results are presented for a wide range of important variables. In particular, the prediction of lubricant supply rate is studied carefully and compared with data presented in a widely used design aid which does not account in detail for the influence of film reformation.

scholarly journals The κ-statistics approach to epidemiology

2020 ◽  
Author(s):  
Giorgio Kaniadakis ◽  
Mauro M. Baldi ◽  
Thomas S. Deisboeck ◽  
Giulia Grisolia ◽  
Dionissios T. Hristopulos ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Statistical Approach ◽  
Weibull Model ◽  
Distribution Functions ◽  
Statistical Distributions ◽  
Systematic Analysis ◽  
Epidemiological Analysis ◽  
Theoretical Predictions ◽  
Theoretical Results ◽  
Good Agreement

Abstract A great variety of complex physical, natural and artificial systems are governed by statistical distributions, which often follow a standard exponential function in the bulk, while their tail obeys the Pareto power law. The recently introduced κ-statistics framework predicts distribution functions with this feature. A growing number of applications in different fields of investigation are beginning to prove the relevance and effectiveness of κ-statistics in fitting empirical data. In this paper, we use κ-statistics to formulate a statistical approach for epidemiological analysis. We validate the theoretical results by fitting the derived κ-Weibull distributions with data from the plague pandemic of 1417 in Florence as well as data from the COVID-19 pandemic in China over the entire cycle that concludes in April 16, 2020. As further validation of the proposed approach we present a more systematic analysis of COVID-19 data from countries such as Germany, Italy, Spain and United Kingdom, obtaining very good agreement between theoretical predictions and empirical observations. For these countries we also study the entire first cycle of the pandemic which extends until the end of July 2020. The fact that both the data of the Florence plague and those of the Covid-19 pandemic are successfully described by the same theoretical model, even though the two events are caused by different diseases and they are separated by more than 600 years, is evidence that the κ-Weibull model has universal features.

scholarly journals The κ-statistics approach to epidemiology

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Giorgio Kaniadakis ◽  
Mauro M. Baldi ◽  
Thomas S. Deisboeck ◽  
Giulia Grisolia ◽  
Dionissios T. Hristopulos ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Statistical Approach ◽  
Weibull Model ◽  
Distribution Functions ◽  
Statistical Distributions ◽  
Systematic Analysis ◽  
Epidemiological Analysis ◽  
Theoretical Predictions ◽  
Theoretical Results ◽  
Good Agreement

AbstractA great variety of complex physical, natural and artificial systems are governed by statistical distributions, which often follow a standard exponential function in the bulk, while their tail obeys the Pareto power law. The recently introduced $$\kappa $$ κ -statistics framework predicts distribution functions with this feature. A growing number of applications in different fields of investigation are beginning to prove the relevance and effectiveness of $$\kappa $$ κ -statistics in fitting empirical data. In this paper, we use $$\kappa $$ κ -statistics to formulate a statistical approach for epidemiological analysis. We validate the theoretical results by fitting the derived $$\kappa $$ κ -Weibull distributions with data from the plague pandemic of 1417 in Florence as well as data from the COVID-19 pandemic in China over the entire cycle that concludes in April 16, 2020. As further validation of the proposed approach we present a more systematic analysis of COVID-19 data from countries such as Germany, Italy, Spain and United Kingdom, obtaining very good agreement between theoretical predictions and empirical observations. For these countries we also study the entire first cycle of the pandemic which extends until the end of July 2020. The fact that both the data of the Florence plague and those of the Covid-19 pandemic are successfully described by the same theoretical model, even though the two events are caused by different diseases and they are separated by more than 600 years, is evidence that the $$\kappa $$ κ -Weibull model has universal features.

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.

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