Wyniki wyszukiwania - Biblioteka Nauki

1

Failure of magnetic fluid seals operating in water: preliminary conclusions

100%

Matuszewski L.

Polish Maritime Research

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2017

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tom nr 2

113--120

EN

The article analyses properties of magnetic fluid seals installed in rotary sealing nodes which operate in the utility water environment. Seals of this type have been examined as a possible solution to the problem with ship manoeuvring propulsion sealing. The present analysis bases on laboratory durability tests of magnetic fluid seals exposed to longterm utility water loads, at different water pressures and shaft revolutions. The basic seal durability criterion was the number of revolutions made by the sealing node shaft until the appearance of water tightness loss (leakage). It was found that the main factor leading to the wear of the seal is the relative speed of the magnetic fluid with respect to that of the utility water, and this process is heavily affected by the pressure acting on the seal. The reported test results are presented in the form of diagrams showing the seal durability (time until water tightness loss) as a function of rotational speed. The curves shown in the diagrams are regular, with two different rotational speed ranges: the highspeed range, when the tightness loss is relatively fast, and the low-speed range, with a clear tendency to prolong the seal lifetime. These diagrams were given the name of durability curves of the MF seal operating in water. The results of the performed tests suggest formal similarity between the experimental data distribution concerning tightness loss processes occurring in magnetic fluid seals operating in water environment and metal fatigue processes. The article proposes a preliminary simplified durability model to describe the examined phenomenon.

2

Soversenstvovanie konstrukcji kombinirovanyh magnitozidkostnyh germetizatorov, prednaznacennyh dla zameny beskontaktnyh uplotnenij

100%

Vinogradov A. , Radionov A. , Kazakuca A.

Zeszyty Naukowe Politechniki Świętokrzyskiej. Nauki Techniczne

|

2008

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tom Z. 10, Vol. 2

19-26

EN

The ways of improvement of combined magnetic fluid seals for bearing units are proposed. Some new models of large electric motors bearing units combined MFS are described.

3

O modelirovanii povedenia magnitnoj zidkosti v kol'cevom zazore germetizatora

80%

Selezov I. , Radionov A.

Zeszyty Naukowe Politechniki Świętokrzyskiej. Nauki Techniczne

|

2008

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tom Z. 10, Vol. 2

27-32

EN

Behavior of magnetic fluid in the ring gap of magnetic fluid seal is considered. The system of equations, the numerical solution of which will permit to determine the fields of temperature, pressure, density and magnetization in the ring gap of magnetic fluid seal is proposed.

4

Uproszczony sposób wyznaczania charakterystyk reologicznych cieczy magnetycznych

80%

Kęsy Z.

Hydraulika i Pneumatyka

|

2008

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tom nr 5

16-21

PL

Przedstawiono uproszczony sposób wyznaczania charakterystyk reologicznych cieczy magnetycznej dla przepływu ciśnieniowego w oparciu o przyrząd pomiarowy nowej konstrukcji. Badano dwa rodzaje cieczy magnetycznych. Sporządzone charakterystyki reologiczne porównano z charakterystykami otrzymanymi w typowy sposób.

EN

In the paper simplified method of magnetic fluid rheological characteristics determination for flow mode is presented. Two magnetic fluids consisting of iron parts and silicon oil were tested. The fluids tests were performed on specially designed test rig. The simplified method results were compared with results obtained in typical way.

5

Detection of structural transformations in magnetic fluids for biomedical application by ultrasound

80%

Józefczak A.

Molecular and Quantum Acoustics

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2008

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tom Vol. 29

121-133

EN

Acoustic spectroscopy has been used to investigate the effect of surface-coating layers in biocompatible magnetic fluids. The method applied is sensitive to structural changes in the suspension as the ultrasonic attenuation is correlated with the concentration of particles and the particle size distribution. The structural characteristics (aggregation phenomena) of the magnetic fluids with a single and double layer of a surfactant on magnetic field sweep have been analyzed on the basis of ultrasound attenuation measured for different frequencies of the acoustic wave.

6

Detection of structural transformations in magnetic fluids for biomedical application by ultrasound

80%

Józefczak A.

Molecular and Quantum Acoustics

|

2007

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tom Vol. 28

137-149

EN

Acoustic spectroscopy has been used to investigate the effect of surface-coating layers in biocompatible magnetic fluids. The method applied is sensitive to structural changes in the suspension as the ultrasonic attenuation is correlated with the concentration of particles and the particle size distribution. The structural characteristics (aggregation phenomena) of the magnetic fluids with a single and double layer of a surfactant on magnetic field sweep have been analyzed on the basis of ultrasound attenuation measured for different frequencies of the acoustic wave.

7

Determination of Magnetic Particle Size Using Ultrasonic, Magnetic and Atomic Force Microscopy Methods

80%

Zieliński B. , Skumiel A. , Józefczak A. , Vandeweert E.

Molecular and Quantum Acoustics

|

2005

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tom Vol. 26

309-316

8

Transport of vorticity in fluid in the presence of suspended magnetic particles in porous medium

70%

Sunil

Applied Mechanics and Engineering

|

1999

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tom Vol. 4, no 1

35-43

EN

Transport of vorticity in a magnetic fluid in a porous medium is considered in this note. Equations governing the transport of vorticity in magnetic fluid in a porous medium are obtained from the equations of magnetic fluid flow proposed by Wagh (1996) by replacing the usual viscous term in the equation of fluid motion by the resistance term __ to discuss the transport of vorticity in magnetic fluid in a porous medium. A two-dimensional case is also studied.

9

Magnetic fluid as lubricant: adhesive properties

70%

Sokolov N. A. , Bausov A. M.

Applied Mechanics and Engineering

|

1999

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tom Vol. 4, no spec.

297-300

EN

The results of the investigation of adgesiv-moistening properties of lubricating medium, that is magnetic fluid (MF) is introduced in this paper. Methods and the resalt of the experiments of defining moistening properties without boundary angles measurement and fluid surface tension are presented in the paper. The existance of magnetic constituent adhesion was proved experimentally and on the basis of this fact the authors make their conclusion about possibility of quantity optimization of MF in the contact zone of magnetically soft materials.

10

Badania właściwości cieczy magnetycznych

70%

Kęsy Z.

Hydraulika i Pneumatyka

|

2009

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tom nr 3

14-17

PL

Przedstawiono sposoby określania właściwości cieczy magnetycznej MRF-132AD. Charakterystyki reologiczne cieczy badano na reometrze Physica MCR 301 typu płytka - płytka. Oceniono także odporność tej cieczy na rozwarstwienie, będące skutkiem występowania przyspieszeń dośrodkowych podczas wirowania.

EN

In this paper testing methods of magnetic fluid MRF-132AD are presented. Rheological characteristics of the fluid with Physica MCR 301 rheometer plate-plate type were investigated. The resistance of that fluid for stratification, as a result of the centripetal acceleration during centrifugation has been assessed.

11

Kinematically Excited Vibration of an Asymmetric Rotor/Bearing System With Magnetic Lubricant

70%

Perek A. , Kurnik W.

Machine Dynamics Research

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2015

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tom Vol. 39, No. 4

5-19

EN

The paper is concerned with transverse dynamics of a rigid rotor supported in a semi-active slide bearing lubricated with a magnetic fluid. Attention is focused on modeling and simulation of forced vibrations of an asymmetric rotor supported in a rolling bearing at one end and in a slide bearing, on the other one. The slide bearing is treated as a nonlinear flexible support with visco-elastic properties controlled by an external magnetic field via a ferrofluid used as a bearing lubricant. The considered dynamical system is a discrete model of real rotor of Rotor Kit RK-4 by Bentley Nevada, a laboratory device being used for educational and research purposes. The aim of the study is to find how a magnetically induced modification of the magnetic fluid affects the resonant behavior of the rotor under harmonic kinematic excitation by the rotor housing movement. Computer simulations are used to obtain resonant curves of nonlinear relative rotor/housing vibrations. The effects of magnetically controlled viscosity of the lubricant fluid are presented as changes of shape and maximum values of the resonant curves as well as a shift of the resonance zone in the excitation frequency domain.

12

Projekt i realizacja sprzęgła magnetoreologicznego ze wzbudzeniem hybrydowym

60%

Kowol P. , Pilch Z.

Napędy i Sterowanie

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2012

|

tom R. 14, nr 7/8

78--83

PL

Sprzęgło, będące elementem układu napędowego, służące do łączenia wałów i przekazywania momentu obrotowego, składa się z członu czynnego – napędzającego – i członu biernego – napędzanego oraz z łącznika [1]. Łącznik rozumiany jest jako część (kilka części) lub jako czynnik, który określa sposób przekazania momentu oraz charakteryzuje sprzęgło. W sprzęgłach sterowanych elektromagnetycznie łącznik zmienia swoje parametry pod wpływem pola magnetycznego wytworzonego przez cewkę zasilaną prądem. Jednym z rodzajów sprzęgieł elektromagnetycznych są sprzęgła, w których łącznikiem (czynnikiem sprzęgającym) jest ciecz magnetoreologiczna.

EN

In the paper the properties of magnetorheological (MR) fluids and the principles of operations of magnetorheological clutch are described. The magnetorheological clutch with hybrid excitation is presented. Two types of design calculations – magnetic calculations and mechanical calculations – are described. The magnetic design calculations allow to determine geometric parameters of magnetic circuit: number of discs, their thickness and dimensions of the permanent magnet. Using the magnetic field distributions obtained from magnetic field calculations and catalog parameters of the magnetorheological fluid the clutching torque versus coil current TS(I) characteristic is determined. The mechanical calculations allow to verify correctness of the clutch construction – mainly geometric parameters of the shaft and discs. The prototype of the magnetorheological clutch, which is a final effect of the design calculations and constructional works, was researched on the dedicated test bench. The researches of the prototype of the magnetorheological clutch were related to measurements of static and dynamic states of the clutch work.

13

Squeeze film based magnetic fluid in between porous circular disks with sealed boundary

60%

Deheri G. M. , Patel R. M.

International Journal of Applied Mechanics and Engineering

|

2006

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tom Vol. 11, no 4

803-812

EN

Efforts have been made to study the effect of the magnetic fluid lubricant and the sealing of the boundary for the squeeze film between two circular disks when the upper disk having a porous facing with its boundary sealed, approaches the non-porous lower disk normally. The modified Reynolds equations for the fluid region and the governing Laplacian equation for the pressure in a porous region are solved with appropriate boundary conditions. Expressions are obtained for pressure, load carrying capacity and the response time. The results are presented graphically. The combined effect of the magnetic fluid lubricant and sealing of the boundary increases the load carrying capacity significantly and hence the performance of the bearing can be enhanced considerably by sealing the boundary and taking a magnetic fluid as lubricant.

14

Przetworniki elektromagnetyczne z cieczą magnetyczną

60%

Szeląg W.

Zeszyty Naukowe Politechniki Poznańskiej. Elektryka

|

2006

|

tom Nr 51

65-84

PL

W artykule przedstawiono ciecze reologiczne o właściwościach sterowanych polem magnetycznym oraz wskazano ich zastosowania w przetwornikach elektromagnetycznych. Zaprezentowano przetworniki opracowane na Politechnice Poznańskiej. Do analizy stanów pracy przetworników z cieczą magnetyczna zaproponowano model polowy nieustalonych zjawisk sprzężonych: elektromagnetycznych, hydrodynamicznych, cieplnych oraz mechanicznych. Przedstawiono opracowany algorytm i program symulacji zjawisk sprzężonych w hamulcach magnetoreologicznych. Zaprezentowano wybrane wyniki symulacji i badań hamulca modelowego.

EN

The paper deals with magnetic fluids whose properties change in the presence of a magnetic field and shows how they can be applied in electromagnetic transducers. The electromagnetic brakes and dampers with magnetorheological fluid made in Poznań University of Technology has been shown. A field model of coupled electromagnetic, hydro-dynamic, thermodynamic and mechanical motion phenomena in brake with magnetic fluid is presented. The numerical implementation of the mathematical model is based on the finite element method and a step-by-step algorithm. Saturation, eddy currents, rotor movements, non-linear properties and the flow of the fluid have been taken into account. A computer program based on this algorithm was used to simulate the transients in a prototype of magnetorheological brake. The results of the calculations and measurements are presented.

15

Multi-stage magnetic-fluid seals for operating in water – life test procedure, test stand and research results. Part. I. Life test procedure, test stand and instrumentation

60%

Matuszewski L.

Polish Maritime Research

|

2012

|

tom nr 4

62--70

EN

The edge criteria for magnetic-fluid seals durability research are critical for the seal’s technological usefulness. The magnetic fluid seal technology in water is much more difficult technological problem in comparison to gas or vacuum environment. There is always problem with immediate contact between magnetic fluid and the environmental uninspected liquids. In the paper are presented ways of experiments definitions carried out with multi-stage rotating magnetic fluid seal operating in permanent contact with utility water. The special test procedures have been elaborated and practically used, with the aim to define main characteristics of magnetic fluid seals. These characteristics were: critical pressure, critical motion velocity and working life of the seal. Some grades of commercial, silicon based magnetic fluids of hydrophobic properties were tested in sealing system. The test stand and its features as well as results of tests are presented in the form of tables, cross section draws and diagrams. In conclusion one can see that multi-stage magnetic-fluid seals could be efficiently used in water for rotating shaft seals in a limited range of motion velocity and work lasting.

16

Magnetic fluid pressure on fingering phenomenon through homogeneous porous media

60%

Shah R. C.

International Journal of Applied Mechanics and Engineering

|

2004

|

tom Vol. 9, no 3

613-618

EN

This paper studied theoretically the net effect of pressure and the consequences arising due to the addition of a layer of a magnetic fluid to the fingering phenomenon through homogeneous porous media by comparing the model with the conventional one.

17

From magnetic fluids up to complex biocompatible nanosized magnetic systems

60%

Morais P. C.

Bulletin of the Polish Academy of Sciences. Technical Sciences

|

2008

|

tom Vol. 56, nr 3

254-262

EN

The paper presents magnetic fluid as an excellent material platform for producing more complex magnetic drug delivery systems. In addition, the paper discusses the nanoparticle morphological (electron microscopy) and structural (X-ray diffraction) characterizations. Mössbauer spectroscopy and photoacoustic spectroscopy are revisited as key tools in the characterization of the magnetic core and diamagnetic shell of the magnetic nanoparticle, respectively.

18

Magnetic fluid seals - materials, design, application

60%

Szydło Z. , Ochoński W. , Zachara B. , Rudnicki Z.

Problemy Eksploatacji

|

1998

|

tom nr 3

309-322

EN

The authors present material and design problems of ferrofluid seals application in both static or dynamic conditions with their advantages or shortcomings discussion. Typical magnetic materials used for magnetic liquids and magnetic circuit elements are set up with comparison of their properties. Presented and discussed are also some basic relations for determination the pressure capability of a ferrofluid seal and its geometrical characteristics. Considered matters are illustrated by examples of ferrofluid seals application.

PL

Autorzy prezentują zagadnienia materiałowe i konstrukcyjne w zastosowaniach uszczelnień z cieczami ferromagnetycznymi w warunkach statycznych i dynamicznych. Zestawiono typowe materiały stosowane w cieczach magnetycznych, jak również elementy obwodów magnetycznych i porównano ich właściwości. Podano i omówiono podstawowe zależności służące do określania nośności uszczelnienia oraz jego geometrycznej charakterystyki. Omówione zagadnienia zilustrowano przykładami zastosowania uszczelnień z cieczami ferromagnetycznymi.

19

Analiza zjawisk sprzężonych w przetwornikach elektromagnetycznych z cieczą magnetyczną

60%

Szeląg W.

Zeszyty Naukowe Politechniki Poznańskiej. Elektryka

|

2004

|

tom Nr 48

115-127

PL

W artykule przedstawiono ciecze reologiczne o właściwościach sterowanych polem magnetycznym oraz wskazano ich zastosowania w przetwornikach elektromagnetycznych. Do analizy stanów pracy przetworników z cieczą magnetyczną zaproponowano polowy model zjawisk sprzężonych elektromagnetycznych, hydrodynamicznych, cieplnych oraz mechanicznych. Przedstawiono opracowany algorytm i program symulacji zjawisk sprzężonych w hamulcach magnetoreologicznych. Zaprezentowano wybrane wyniki symulacji i badań hamulca modelowego.

EN

The paper deals with magnetic fluids whose properties change in the presence of a magnetic field and shows how they can be applied in electromagnetic transducers. A field model of coupled electromagnetic, hydrodynamic, thermodynamic and mechanical motion phenomena in brake with magnetic fluid is presented. The numerical implementation of the mathematical model is based on the finite element method and a step-by-step algorithm. Saturation, eddy currents, rotor movements, non-linear properties and the flow of the fluid have been taken into account. A computer program based on this algorithm was used to simulate the transients in a prototype of magnetorheological brake. The results of the calculations and measurements are presented.

20

Multi-stage magnetic-fluid seals for operating in water - life test procedure, test stand and research results. Part II Results of life tests of multi-stage magnetic - fluid seal operating in water

60%

Matuszewski L.

Polish Maritime Research

|

2013

|

tom nr 1

39--47

EN

The edge criteria for magnetic-fluid seals durability research were described in previous article [24] and now the tests results are presented. The tests were made with three magnetic fluids using various magnets quantity in magnetic assemblies. If values obtained in the repeated test deviated by more than 10 % from results of the first test an additional control test was made for final characteristics. The characteristics are: critical pressure, critical motion velocity and working life of the seal. The test stands were prepared for particular seals dimensions and results of tests are presented in the form of tables, cross section draws and diagrams. In conclusion one can see that multi-stage magnetic-fluid seals could be efficiently used in water for rotating shaft seals in a limited range of motion velocity and cycles quantity. Nevertheless a particular applications can be provided by magnetic-fluid seals only.