Session: 11-18-01: Fundamental Issues in Fluid Mechanics/Rheology of Nonlinear Materials and Complex Fluids/Plasma Flow

Paper Number: 166046

Hydrodynamic Performance of a Magnetorheological Squeeze Film Damper Through Mason Number 

MR fluid-based technology provides better operating conditions in vibration absorption mechanisms, considering the rheological versatility of MR fluid, which involves changing from liquid-like to solid-like behavior when a magnetic field is applied. The oil film in a squeeze film damper dissipates the friction between rolling elements. In addition, this fluid layer acts as a damping element to attenuate mechanical vibrations generated by rotor instability. In this context, implementing a MR fluid instead of a traditional lubricant improves the damping capacity of the device. This improvement in the damper performance lies in the capacity of the fluid to increase its resistance to deformation by the effect of a magnetic field. Therefore, this work analyzes the behavior of a magnetorheological squeeze film damper under the short bearing approximation. MR fluid is a dispersion of ferromagnetic particles in a carrier fluid. Typically, the particles are pure iron, iron carbonyl, or cobalt powder, and the carrier fluid is a non-magnetic Newtonian liquid. The Bingham rheological model describes the hydrodynamic response of the MR fluid to a magnetic field. Without magnetic field strength, MR fluid acts as a liquid whose viscosity depends on the particle concentration. Meanwhile, when subjected to a magnetic field, MR fluid adopts the behavior of a semi-solid. Under this condition, the fluid develops chain-like structures that inhibit motion. The mechanical resistance of the MR fluid, expressed by the threshold value known as yield stress, enhances as the magnetic field increases. Hence, the MR fluid will flow when a shear stress exceeds the yield stress, resulting in partial or complete rupture of the chain-like structure. The continuity and momentum equations, the rheological model, and the boundary conditions establish the mathematical model to simulate the flow characteristics of the MR fluid. Moreover, the short bearing approximation simplifies the Reynolds equation to a hydrodynamic analysis over the damper width. The dimensionless parameters derived from the mathematical model evaluate the velocity field and the pressure distribution. These parameters are the pressure gradient, the field-dependent yield stress, the viscosity of the MR suspension, the fluid thickness affected by the eccentricity of the system, and the Mason number that indicates the ratio of hydrodynamic stress to magnetic stress. Although the scientific community has reported several studies related to MR dampers, the hydrodynamic evaluation combining the macroscopic model of the damper with the microscopic characteristics of the MR fluid has not been analyzed. This work contributes to the understanding of MR dampers by incorporating the microstructural characteristics of the fluid.

Presenting Author: Juan R. Gómez Instituto Politécnico Nacional, SEPI-ESIME Unidad Azcapotzalco, Departamento de Termofluidos

Presenting Author Biography: Mechanical Engineer and MSc in Thermofluids by the Instituto Politécnico Nacional in Mexico. Currently studying a PhD in Thermofluids at the Escuela Superior de Ingeniería Mecánica y Eléctrica of the Instituto Politécnico Nacional in Mexico. Areas of interest in electrokinetic and magnetohydrodynamic flows, transport phenomena in heat transfer and fluid flow, micropumps, fluid rheology, and magnetorheological dampers. Several publications in journals indexed in the Master Journal List of Web of Science. Participation in ASME conferences since 2017.

Authors:

Juan P. Escandón Instituto Politécnico Nacional, SEPI-ESIME Unidad Azcapotzalco, Departamento de Termofluidos
Juan R. Gómez Instituto Politécnico Nacional, SEPI-ESIME Unidad Azcapotzalco, Departamento de Termofluidos
David A. Torres Universidad Tecnológica de Tula-Tepeji, Programa Educativo de Ingeniería Química