Abstract

Electro‐Rheological (ER) fluid behavior is similar to Bingham fluid’ s. Only when the shear stress magnitude of ER fluid exceeds the yield stress, Newtonian flow results. Continuous shear strain rate equation about shear stress which simulates Bingham‐like fluid shows viscosity variations. Shear yield stress is controlled by electric fields. Electric fields in circumferential direction around the journal are also changeable because of gap distance. These values make changes of spring and damping coefficients of journal bearings compared to Newtonian flow case. Implicit viscosity variation effects according to shear strain rates of fluid are included in generalized Reynolds′ equation for submerged journal bearing. Fluid film pressure and perturbation pressures are solved using switch function of Elord′s algorithm for cavitation boundary condition. Spring and damping coefficients are obtained for several parameters that determine the characteristics of ER fluids under a certain electric field. From these values stability region for simple rotor‐bearing system is computed. It is found that there are no big differences in load capacities with the selected electric field parameters at low eccentric region and higher electric field can support more load with stability at low eccentric region.

Highlights

  • Electro-Rheological fluid (ER fluid) changes its rheology of dispersions upon application of electric fields

  • ER fluid behavior is very similar to Bingham fluid model, which is characterized by two parameters: a

  • Active control of rotor dynamic behavior can be obtained by applying electric field on the bearing-journal surfaces

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Summary

Printed in Malaysia

Internal Damper Characteristics of Rotor System with Submerged ER Fluid Journal Bearing. Electric fields in circumferential direction around the journal are changeable because of gap distance. These values make changes of spring and damping coefficients of journal bearings compared to Newtonian flow case. Implicit viscosity variation effects according to shear strain rates of fluid are included in generalized Reynolds’ equation for submerged journal bearing. Spring and damping coefficients are obtained for several parameters that determine the characteristics of ER fluids under a certain electric field. From these values stability region for simple rotor-bearing system is computed. Keywords." Electro-Rheological Fluid, Dynamic Coefficient, Reynolds’ Equation, Bingham Fluid, Switch Function, Rotor-Bearing System Stability

INTRODUCTION
Fluid Film Pressure with ER Lubricant
Dimensionless Shear Rate
The magnitude of shear rate is expressed by z
Calculation of Dynamic Coefficients
ER Fluid Bearing
Journal Bearing Stability
RESULTS
CONCLUSION
Full Text
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