scholarly journals Study on the Unbalanced Curl Seal Failure of the Magnetorheological Fluid Sealing Device of the Hydraulic Turbine Main Shaft under Different Speed Abrupt Conditions

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1171
Author(s):  
Jie Cheng ◽  
Zheng-Gui Li ◽  
Yang Xu ◽  
Wang-Xu Li ◽  
Xin-Rui Li
Keyword(s):  
Magnetic Field ◽  
Sudden Change ◽  
Hydraulic Turbine ◽  
Frictional Heat ◽  
Main Shaft ◽  
Mr Fluid ◽  
Friction Heat ◽  
Sealing Ability ◽  
Sealing Failure ◽  
Sealing Device

The fluid flow in the runner of a hydraulic turbine has serious uncertainties. The sealing failure of the magnetorheological (MR) fluid sealing device of the main shaft of the hydroturbine, caused by a sudden change in speed, has always been a difficult topic to research. This study first derives the MR fluid seal pressure and unbalanced curl equations of the hydroturbine main shaft, and then analyzes the seal pressure and friction heat under different rotational speed mutation conditions through experiments. After verification, the temperature field and magnetic field distribution of the MR fluid sealing device of the main shaft of the hydraulic turbine are obtained via numerical calculation. The results show that the external magnetic field affects the magnetic moment of the magnetic particles in the MR fluid, resulting in a significant change in frictional heat, thereby reducing the saturation of magnetic induction intensity of the MR fluid. This results in a decrease in the sealing ability of the device. The size and abrupt amplitude of the main shaft of the hydraulic turbine, and friction heat is positively correlated reducing the sealing ability of the device and causing sealing failure. Based on our results, we recommend adding the necessary cooling to the device to reduce the frictional heat, thereby increasing the seal life of the device.

Investigation of ultrasonic properties of MR fluid under various sweep rates of magnetic field

2013 ◽  
Vol 49 (3-4) ◽  
pp. 430-433
Author(s):  
A. Isnikurniawan ◽  
Y. Fujita ◽  
S. Tanimoto ◽  
T. Sawada
Keyword(s):  
Magnetic Field ◽  
Mr Fluid ◽  
Ultrasonic Properties

Internal Organizational Measurement for Control of Magnetorheological Fluid Properties

2006 ◽  
Vol 129 (4) ◽  
pp. 423-428 ◽  
Author(s):  
John R. Lloyd ◽  
Miquel O. Hayesmichel ◽  
Clark J. Radcliffe
Keyword(s):  
Magnetic Field ◽  
Physical Properties ◽  
High Sensitivity ◽  
Time Varying ◽  
Measurable Effect ◽  
Mr Fluid ◽  
Fluid State ◽  
Mr Fluids ◽  
Fluid Properties ◽  
Field Excitation

Magnetorheological (MR) fluids change their physical properties when subjected to a magnetic field. As this change occurs, the specific values of the physical properties are a function of the fluid’s time-varying organization state. This results in a nonlinear, hysteretic, time-varying fluid property response to direct magnetic field excitation. Permeability, resistivity and permittivity changes of MR fluid were investigated and their suitability to indicate the organizational state of the fluid, and thus other transport properties, was determined. High sensitivity of permittivity and resistivity to particle organization and applied field was studied experimentally. The measurable effect of these material properties can be used to implement an MR fluid state sensor.

A New Unified Approach for Flow Analysis of Magneto-Rheological Fluids

Aerospace ◽  
2004 ◽  
Author(s):  
Barkan M. Kavlicoglu ◽  
Faramarz Gordaninejad ◽  
Xiaojie Wang ◽  
Gregory Hitchcock
Keyword(s):  
Magnetic Field ◽  
Surface Roughness ◽  
Pressure Loss ◽  
Flow Analysis ◽  
Volumetric Flow Rate ◽  
Mr Fluid ◽  
Mason Number ◽  
Universal Approach ◽  
Shear Yield ◽  
Magneto Rheological

The focus of this study is to develop a new universal approach for the flow analysis of magneto-rheological (MR) fluids through channels. An experimental study is conducted to investigate the relationship between the pressure loss of a MR fluid as a function of the applied magnetic field strength, volumetric flow rate, and surface roughness without utilizing the assumption of shear yield stress. A relation for nondimensional friction factor is developed in terms of Mason number and dimensionless surface roughness. It is demonstrated that the pressure loss across the MR fluid flow channel is significantly affected by the magnetic field and the surface roughness.

Platform Design for Characterizing Shear Force Produced by Magnetized Magnetorheological Fluid

2019 ◽  
Author(s):  
Ping-Hsun Lee ◽  
Jen-Yuan (James) Chang
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Yield Stress ◽  
Flux Density ◽  
Shear Force ◽  
Permanent Magnets ◽  
Magnetic Flux Density ◽  
Finite Element Method Result ◽  
Mr Fluid ◽  
The Magnetic Field

Abstract In this paper we proposed a platform for measuring shear force of magnetorheological (MR) fluid by which the relationship of yield stress and magnetic flux density of specific material can be determined. The device consisted of a rotatable center tube in a frame body and the magnetic field was provided by two blocks of permanent magnets placed oppositely outside the frame body. The magnitude and direction of the magnetic field were manipulated by changing the distance of the two permanent magnets from the frame body and rotating the center tube, respectively. For determining the magnetic field of the device, we adopted an effective method by fitting the FEM (finite element method) result to the measured one and then rebuilt the absent components to approximate the magnetic field, which was hardly to be measured simultaneously as different device setup were required. With the proposed platform and analytical methods, the drawing shear force and the corresponding yield stress contributed by MR fluid could be evaluated in respect to the magnitude and direction of given magnetic flux density with acceptable accuracy for specific designing purposes without a large, complex, and expensive instrument.

scholarly journals Modeling the Response of Magnetorheological Fluid Dampers under Seismic Conditions

2019 ◽  
Vol 9 (19) ◽  
pp. 4189 ◽  
Author(s):  
Darson Dezheng Li ◽  
Declan Finn Keogh ◽  
Kevin Huang ◽  
Qing Nian Chan ◽  
Anthony Chun Yin Yuen ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Pressure Drop ◽  
Fluid Velocity ◽  
Pressure Profile ◽  
Inlet Pressure ◽  
Mr Fluid ◽  
Pressure Profiles ◽  
Efficiency And Effectiveness ◽  
Fluid Dampers ◽  
Mr Fluid Damper

Magnetorheological (MR) fluid is a smart material fabricated by mixing magnetic-responsive particles with non-magnetic-responsive carrier fluids. MR fluid dampers are able to provide rapid and reversible changes to their damping coefficient. To optimize the efficiency and effectiveness of such devices, a computational model is developed and presented where the flow field is simulated using the computational fluid dynamics approach, coupled with the magnetohydrodynamics model. Three different inlet pressure profiles were designed to replicate real loading conditions are examined, namely a constant pressure, a sinusoidal pressure profile, and a pressure profile mimicking the 1994 Northbridge earthquake. When the MR fluid damper was in its off-state, a linear pressure drop between the inlet and the outlet was observed. When a uniform perpendicular external magnetic field was applied to the annular orifice of the MR damper, a significantly larger pressure drop was observed across the annular orifice for all three inlet pressure profiles. It was shown that the fluid velocity within the magnetized annular orifice decreased proportionally with respect to the strength of the applied magnetic field until saturation was reached. Therefore, it was clearly demonstrated that the present model was capable of accurately capturing the damping characteristics of MR fluid dampers.

scholarly journals Application Of CFD To Modeling Of Squeeze Mode Magnetorheological Dampers

2015 ◽  
Vol 9 (3) ◽  
pp. 129-134 ◽  
Author(s):  
Janusz Gołdasz ◽  
Bogdan Sapiński
Keyword(s):  
Magnetic Field ◽  
Yield Stress ◽  
Flow Model ◽  
Squeeze Flow ◽  
Channel Height ◽  
Ansys Fluent ◽  
Mr Fluid ◽  
Planar Surfaces ◽  
Force Profile ◽  
Magnetic Field Magnitude

Abstract The so-called squeeze flow involves a magnetorheological (MR) fluid sandwiched between two planar surfaces setting up a flow channel. The height of the channel varies according to a prescribed displacement or force profile. When exposed to a magnetic field of sufficient strength MR fluids develop a yield stress. In squeeze-mode devices the yield stress varies with both the magnetic field magnitude and the channel height. In this paper an unsteady flow model of an MR fluid in squeeze mode is proposed. The model is developed in Ansys Fluent R16. The MR material flow model is based on the apparent viscosity approach. In order to investigate the material's behaviour the authors prepared a model of an idealized squeeze-mode damper in which the fluid flow is enforced by varying the height of the channel. Using mesh animation, the model plate is excited, and as the mesh moves, the fluid is squeezed out of the gap. In the simulations the model is subjected to a range of displacement inputs of frequencies from 10 to 20 Hz, and local yield stress levels up to 30 kPa. The results are presented in the form of time histories of the normal force on the squeezing plate and loops of force vs. displacement (velocity).

MAGNETORHEOLOGICAL FLUIDS AND THEIR PROPERTIES

2005 ◽  
Vol 19 (01n03) ◽  
pp. 593-596 ◽  
Author(s):  
J. M. HE ◽  
J. HUANG
Keyword(s):  
Magnetic Field ◽  
Yield Strength ◽  
Rheological Properties ◽  
Yield Stress ◽  
Applied Magnetic Field ◽  
Magnetorheological Fluids ◽  
Mr Fluid ◽  
Variable Yield ◽  
Mr Fluids

Magnetorheological (MR) fluids are materials that respond to an applied magnetic field with a change in their rheological properties. Upon application of a magnetic field, MR fluids have a variable yield strength. Altering the strength of the applied magnetic field will control the yield stress of these fluids. In this paper, the method for measuring the yield stress of MR fluids is proposed. The curves between the yield stress of the MR fluid and the applied magnetic field are obtained from the experiment. The result indicates that with the increase of the applied magnetic field the yield stress of the MR fluids goes up rapidly.

Behavior of Magnetorheological Fluids

MRS Bulletin ◽  
1998 ◽  
Vol 23 (8) ◽  
pp. 26-29 ◽  
Author(s):  
John M. Ginder
Keyword(s):  
Magnetic Field ◽  
Applied Magnetic Field ◽  
Mr Fluid ◽  
Shock Absorbers ◽  
Aerospace Applications ◽  
Large Structures ◽  
Potential Applications ◽  
Restoring Forces ◽  
Newtonian Liquids ◽  
Er Fluids

In the absence of an applied magnetic field, magnetorheological (MR) fluids typically behave as nearly ideal Newtonian liquids. The application of a magnetic field induces magnetic dipole and multipole moments on each particle. The anisotropic magnetic forces between pairs of particles promote the head-to-tail alignment of the moments and draws the particles into proximity. These attractive interparticle forces lead to the formation of chains, columns, or more complicated networks of particles aligned with the direction of the magnetic field. When these structures are deformed mechanically, magnetic restoring forces tend to oppose the deformation. Substantial field-dependent enhancements of the rheological properties of these materials result, as demonstrated in Figure 1.The myriad potential applications of MR and electrorheological (ER) fluids provide considerable motivation for research on these materials. The availability of fluids with yield stresses or apparent viscosities that are controllable over many orders of magnitude by applied fields enables the construction of electromechanical devices that are engaged and controlled by electrical signals and that require few or no moving parts. Potential automotive applications include electrically engaged clutches for vehicle powertrains and engine accessories as well as semiactive shock absorbers that can adapt in real time to changing road conditions. Semiactive dampers for rotorcraft control surfaces are among the potential aerospace applications. The critical need to mitigate the structural vibrations of large structures has led to the construction of large, high-force MR-fluid-based dampers. A promising application in manufacturing processes is the computer-aided polishing of precision optics in which abrasive particles are suspended in an MR fluid so that the polishing rate is determined in part by the strength of an applied magnetic field.

scholarly journals Analysis and Testing of Chain Characteristics and Rheological Properties for Magnetorheological Fluid

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Song Chen ◽  
Jin Huang ◽  
Hongyu Shu ◽  
Tiger Sun ◽  
Kailin Jian
Keyword(s):  
Magnetic Field ◽  
Rheological Properties ◽  
Magnetic Particle ◽  
Volume Fraction ◽  
Chain Structure ◽  
Field Size ◽  
Digital Holographic Microscopy ◽  
Mr Fluid ◽  
Shear Yield ◽  
Holographic Microscopy

Digital holographic microscopy is presented in this study, which can measure the magnetorheological (MR) fluid in different volume fractions of particles and different magnetic field strengths. Based on the chain structure of magnetic particle under applied magnetic field, the relationships between shear yield stress, magnetic field, size, and volume fraction of MR fluid in two parallel discs are established. In this experiment, we choose three MR fluid samples to check the rheological properties of MR fluid and to obtain the material parameters with the test equipment of MR fluid; the conclusion is effective.

The Effect of Particle Concentration and Magnetic Field on Tribological Behavior of Magneto-Rheological Fluid

2011 ◽  
Vol 314-316 ◽  
pp. 58-61 ◽  
Author(s):  
Wan Li Song ◽  
Chul Hee Lee ◽  
Seung Bok Choi ◽  
Myeong Woo Cho
Keyword(s):  
Magnetic Field ◽  
Friction Coefficient ◽  
Wear Mechanism ◽  
Particle Concentration ◽  
Tribological Behavior ◽  
Wear Loss ◽  
Wear Properties ◽  
Mr Fluid ◽  
Magneto Rheological ◽  
The Magnetic Field

In this paper, the effect of particle concentration and magnetic field on the tribological behavior of magneto-rheological (MR) fluid is investigated using a pin-on-disc tribometer. The wear loss and friction coefficient are measured to study the friction and wear properties of MR fluid. The morphology of the worn pin is also observed by scanning electron microscope (SEM) in order to analyze the wear mechanism. The results obtained in this work show that the wear loss and friction coefficient decrease with increasing particle concentration under the magnetic field. Furthermore, it is demonstrated that the magnetic field has a significant effect on improving tribological properties of MR fluid, especially the one with high particle concentration. The predominant wear mechanism of the MR fluid has been identified as abrasive wear.

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