Static and dynamic performances of ferrofluid lubricated long journal bearing

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Rajesh C. Shah ◽  
Rajiv B. Shah
Keyword(s):  
Internal Combustion Engines ◽  
Journal Bearing ◽  
Static Case ◽  
Jet Engines ◽  
Centrifugal Pumps ◽  
Damping Characteristics ◽  
Automobile Engines ◽  
Dynamic Performances ◽  
Turbine Shaft ◽  
Electrical Motors

Abstract Due to the advantageous property of reduction of load friction, low wear and good damping characteristics, journal bearings are widely used in industry. They are equipping various rotating machineries like small electrical motors to large generators, internal combustion engines, centrifugal pumps, turbine shaft of most jet engines, crankshaft of an automobile engines, etc. In this paper, static and dynamic performances of ferrofluid (FF) lubricated long journal bearing are studied using rotational and translational approach of the journal. Here, FF is controlled by the transverse uniform magnetic field. The modified Reynolds equation is derived by considering FF flow behaviour given by Shliomis and continuity equation in the film region. The dimensionless expressions for load-carrying capacity, frictional force and coefficient of friction are studied for static case, while the dimensionless expressions for stiffness coefficients and damping coefficients are studied for dynamic case. It is observed that comparing with conventional lubricant the bearing performance is significantly modified in the present analysis.

Measurements of Rotordynamic Forces on an Artificial Heart Pump Impeller

2007 ◽  
Vol 129 (11) ◽  
pp. 1422-1427 ◽  
Author(s):  
Takayuki Suzuki ◽  
Romain Prunières ◽  
Hironori Horiguchi ◽  
Tomonori Tsukiya ◽  
Yoshiyuki Taenaka ◽  
...  
Keyword(s):  
Artificial Heart ◽  
Journal Bearing ◽  
Centrifugal Pumps ◽  
Pump Impeller ◽  
Fluid Forces ◽  
Heart Pump ◽  
Wide Range ◽  
Artificial Hearts ◽  
Rotordynamic Forces ◽  
Magnetic Drive

In centrifugal pumps for artificial hearts, a magnetic drive with lightly loaded journal bearing system is often used. In such a system, the rigidity of the bearing is small and the impeller usually rotates over the critical speed. In such cases, the rotordynamic fluid forces play an important role for shaft vibration. In the present study, the characteristics of the rotordynamic fluid forces on the impeller were examined. The rotordynamic fluid forces were measured in the cases with/without the whirling motion. It was found that the rotordynamic forces become destabilizing in a wide range of positive whirl. The effect of leakage flow was also examined.

scholarly journals Dynamic Stiffness and Damping Characteristics of a High-Temperature Air Foil Journal Bearing

2001 ◽  
Vol 44 (4) ◽  
pp. 657-663 ◽  
Author(s):  
Samuela Howard ◽  
Christopher Dellacorte ◽  
Mark J. Valco ◽  
Joseph M. Prahl ◽  
Hooshang Heshmat
Keyword(s):  
High Temperature ◽  
Journal Bearing ◽  
Dynamic Stiffness ◽  
Damping Characteristics ◽  
Stiffness And Damping

A Simple Combustion Efficiency Indicator for Automobile Engines

1973 ◽  
Vol 6 (10) ◽  
pp. 399-400 ◽  
Author(s):  
M. S. Bolton ◽  
D. S. Taylor
Keyword(s):  
Carbon Monoxide ◽  
Internal Combustion Engines ◽  
Fuel Mixture ◽  
Internal Combustion ◽  
Combustion Efficiency ◽  
Exhaust Emission ◽  
Combustion Engines ◽  
Widespread Application ◽  
Mixture Ratio ◽  
Automobile Engines

A cheap device which can indicate carbon monoxide levels in exhaust emission of internal combustion engines, and hence could be used for adjusting the engine's operating air: fuel mixture ratio, would have widespread application in garages, etc. The instrument described here is sensitive to both unburnt hydrocarbons and carbon monoxide but measures the carbon monoxide to an accuracy well within the tuning capability of most carburation systems.

Controlling Journal Bearing Instability Using Active Magnetic Bearings

2007 ◽  
Author(s):  
A. El-Shafei ◽  
A. S. Dimitri
Keyword(s):  
Journal Bearing ◽  
Magnetic Bearing ◽  
Journal Bearings ◽  
Active Magnetic Bearing ◽  
Rotating Speed ◽  
Damping Characteristics ◽  
Oil Whip ◽  
Novel Approach ◽  
Oil Whirl ◽  
Load Carrying

Journal Bearings are excellent bearings due to their large load carrying capacity and favorable damping characteristics. However, Journal bearings are known to be prone to instabilities. The oil whirl and oil whip instabilities limit the rotor maximum rotating speed. In this paper, a novel approach is used to control the Journal bearing (JB) instability. An Active Magnetic Bearing (AMB) is used to overcome the JB instability and to increase its range of operation. The concept is quite simple: rather than using the AMB as a load carrying element, the AMB is used as a controller only, resulting in a much smaller and more efficient AMB. The load carrying is done by the Journal bearings, exploiting their excellent load carrying capabilities, and the JB instability is overcome with the AMB. This results in a combined AMB/JB that exploits the advantages of each device, and eliminates the deficiencies of each bearing. Different controllers for the AMB to control the JB instability are examined and compared theoretically and numerically. The possibility of collocating the JB and the AMB is also examined. The results illustrate the effectiveness of the concept.

Advancements in the Structural Stiffness and Damping of a Large Compliant Foil Journal Bearing: An Experimental Study

2004 ◽  
Vol 129 (1) ◽  
pp. 154-161 ◽  
Author(s):  
Mohsen Salehi ◽  
Hooshang Heshmat ◽  
James F. Walton
Keyword(s):  
Journal Bearing ◽  
Dynamic Stiffness ◽  
Operating Conditions ◽  
Test Facility ◽  
Squeeze Film ◽  
Structural Stiffness ◽  
Low Frequencies ◽  
Equivalent Viscous Damping ◽  
Damping Characteristics ◽  
Stiffness And Damping

This paper presents the results of an experimental investigation into the dynamic structural stiffness and damping characteristics of a 21.6‐cm(8.5in.)-diameter compliant surface foil journal bearing. The goal of this development was to achieve high levels of damping without the use of oil, as is used in squeeze film dampers, while maintaining a nearly constant dynamic stiffness over a range of frequencies and amplitudes of motion. In the experimental work described herein, a full compliant foil bearing was designed, fabricated, and tested. The test facility included a non-rotating journal located inside the bearing. The journal was connected to an electrodynamic shaker so that dynamic forces simulating expected operating conditions could be applied to the structurally compliant bump foil elements. Excitation test frequencies to a maximum of 400Hz at amplitudes of motion between 25.4 and 102μm were applied to the damper assembly. During testing, both compressive preload and unidirectional static loads of up to 1335 and 445N, respectively, were applied to the damper assembly. The experimental data from these tests were analyzed using both a single degree of freedom model and an energy method. These methods of data analysis are reviewed here and results are compared. Excellent agreement in results obtained from the two methods was achieved. Equivalent viscous damping coefficients as high as 1050N.s∕cm(600lbf.s∕in) were obtained at low frequencies. Dynamic stiffness was shown to be fairly constant with frequency.

Advancements in the Structural Stiffness and Damping of a Large Compliant Foil Journal Bearing: An Experimental Study

2004 ◽  
Author(s):  
Mohsen Salehi ◽  
Hooshang Heshmat ◽  
James F. Walton
Keyword(s):  
Journal Bearing ◽  
Dynamic Stiffness ◽  
Operating Conditions ◽  
Test Facility ◽  
Squeeze Film ◽  
Structural Stiffness ◽  
Low Frequencies ◽  
Equivalent Viscous Damping ◽  
Damping Characteristics ◽  
Stiffness And Damping

This paper presents the results of an experimental investigation into the dynamic structural stiffness and damping characteristics of a 21.6 cm (8.5inch) diameter compliant surface foil journal bearing. The goal of this development was to achieve high levels of damping without the use of oil, as is used in squeeze film dampers, while maintaining a nearly constant dynamic stiffness over a range of frequencies and amplitudes of motion. In the experimental work described herein, a full compliant foil bearing was designed, fabricated and tested. The test facility included a non-rotating journal located inside the bearing. The journal was connected to an electrodynamic shaker so that dynamic forces simulating expected operating conditions could be applied to the structurally compliant bump foil elements. Excitation test frequencies to a maximum of 400 Hz at amplitudes of motion between 25.4μm to 102μm were applied to the damper assembly. During testing, both compressive preload and unidirectional static loads of up to 1335N and 445N, respectively, were applied to the damper assembly. The experimental data from these tests were analyzed using both a single degree of freedom model and an energy method. These methods of data analysis are reviewed here and results are compared. Excellent agreement in results obtained from the two methods was achieved. Equivalent viscous damping coefficients as high as 1050 N.s/cm (600 lbf.s/in) were obtained at low frequencies. Dynamic stiffness was shown to be fairly constant with frequency.

scholarly journals AUTOMOBILE INTERNAL COMBUSTION ENGINE PRESSURE CHARGING AND GAS-GUIDE LOW FREQUENCY NOISE REDUCTION USING ACTIVE SOUND SOURCES

Akustika ◽  
2019 ◽  
Vol 34 ◽  
pp. 118-122
Author(s):  
Andrey Vasilyev
Keyword(s):  
Noise Reduction ◽  
Internal Combustion Engines ◽  
Acoustic Pressure ◽  
Combustion Engine ◽  
Low Frequency ◽  
Internal Combustion ◽  
Frequency Noise ◽  
Combustion Engines ◽  
Sound Sources ◽  
Automobile Engines

Pressure charging devices in different types of internal combustion engines is allowing to achieve a number of advantages: engine power and fuel effectiveness increasing, exhaust gases toxic reduction etc. Pressure charging systems may be classified by the different parameters. For the time being turbo-supercharger is the most popular unit of serial automobile engines pressure charging. But it has some negative properties. Therefore using of dynamic (acoustic) pressure charging devices is promising solution. Analysis of existing acoustic pressure charging systems is carried out. The perspectives of using of active sound emitters for acoustic pressure charging are described. Theoretical issues of automobile engines active acoustic charging are discussed. Construction of active charging system is suggested. Multifunctional approach to automobile internal combustion engines pressure charging and low frequency intake and exhaust noise reduction is suggested. The results described in this paper may be useful for further development and application of internal combustion engines with improved consumer’s and ecological characteristic.

scholarly journals Journal Bearing Fault Detection Based on Daubechies Wavelet

2017 ◽  
Vol 42 (3) ◽  
pp. 401-414 ◽  
Author(s):  
Babu T. Narendiranath ◽  
H.S. Himamshu ◽  
Kumar N. Prabin ◽  
Prabha D. Rama ◽  
C. Nishant
Keyword(s):  
Fault Detection ◽  
Time Domain ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Centrifugal Pumps ◽  
Bearing Fault ◽  
Bearing Fault Detection ◽  
Vibration Data ◽  
Target Values

AbstractJournal bearings are widely used to support the shafts in industrial machinery involving heavy loads, such as compressors, turbines and centrifugal pumps. The major problem that could arise in journal bearings is catastrophic failure due to corrosion or erosion and fatigue, which results in economic loss and creates major safety risks. Thus, it is necessary to provide suitable condition monitoring technique to detect and diagnose failures, and achieve cost savings to the industry. Therefore, this paper focuses on fault diagnosis on journal bearing using Debauchies Wavelet-02 (DB-02). Nowadays, wavelet transformation is one of the most popular technique of the time-frequency-transformations. An experimental setup was used to diagnose the faults in the journal bearing. The accelerometer is used to collect vibration data, from the journal bearing in the form of time domain. This was then used as input for a MATLAB code that could plot the time domain signal. This signal was then decomposed based on the wavelet transform. The fast Fourier transform is then used to obtain the frequency domain, which gives us the frequency having the highest amplitude. To diagnose the faults various operating conditions are used in the journal bearing such as Full oil, half loose, half oil, fault 1, fault 2, fault 3 and full loose. Then the Artificial Neural Networks (ANN) is used to classify faults. The network is trained based on data already collected and then it is tested based on random data points. ANN was able to classify the faults with the classification rate of 85.7%. Thus, the test process for unseen vibration data of the trained ANN combined with ideal output target values indicates high success rate for automated bearing fault detection.

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