Session: 10-07-01: Fluid Mechanics and Rheology of Nonlinear Materials and Complex Fluids

Paper Number: 112682

112682 - "Prediction of Pressure Distribution in a Magnetorheological Squeeze Film Damper With Short Bearing Approximation Under Slip Conditions" 

The present work analyzes the pressure distribution in a magnetorheological squeeze film damper that attenuates mechanical vibrations in rotating systems. In these devices, the instability of the rotor represents the main cause of vibrations, however, it is impossible to eliminate this inconvenience since it is produced by manufacturing errors, thermal deformation, assembly tolerance, among other factors. As a result, the eccentricity associated with the rotor angular velocity produces forces acting on the damping element. For this reason, smart materials such as magnetorheological fluids are of interest for this kind of application because they can modify their physical properties in the presence of an external stimulus, such as a magnetic field. This type of fluid is made up of a carrier fluid that contains dispersed magnetic particles that react to the magnetic field, generating chain-shaped structures that act as resistance to movement. In particular, these chains break, and the fluid deforms when the shear stress exceeds the magnitude of the material yield stress. Under this assumption in this study, the working fluid in the squeeze film damper is a magnetorheological fluid described by the Bingham model whose viscosity depends on the intensity of an applied magnetic field. The hydrodynamics of fluid is based on the classical lubrication theory, where the lubricant has complex behavior. In this context, the mathematical model that describes the movement of the fluid is formed by the continuity equation, the momentum equation, and the rheological model. Here, the Reynolds equation is derived to determine the pressure distribution in the system, assuming a short bearing approximation. Additionally, this study assumes that the velocity of the fluid at the top wall corresponds to the journal angular velocity, a hydrodynamic slip boundary condition at the stationary bottom wall, and the channel height depends on the relationship between the bearing clearance and the eccentricity. The results present velocity profiles and pressure distribution as a function of the dimensionless parameters arising from the dimensionless mathematical model. These parameters are the viscosity ratio, the yield stress that involves the effect of the magnetic field, the hydrodynamic slip, and the channel height associated with the angular movement of the journal. Although various investigations are related to magnetorheological squeeze film damper, this combination of parameters has not been studied yet. Therefore, the theoretical results are intended to contribute to understanding magnetorheological squeeze film dampers for applications in rotating machineries such as turbines, pumps, internal combustion engines, electric motors, among others.

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 in the Escuela Superior de Ingeniería Mecánica y Eléctrica of Instituto Politécnico Nacional at Mexico. Interest areas 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. R. Gómez Instituto Politécnico Nacional, SEPI-ESIME Unidad Azcapotzalco, Departamento de Termofluidos
Juan P. Escandón Instituto Politécnico Nacional, SEPI-ESIME Unidad Azcapotzalco, Departamento de Termofluidos
René O. Vargas Instituto Politécnico Nacional, SEPI-ESIME Unidad Azcapotzalco, Departamento de Termofluidos
Edson M. Jimenez Instituto Politécnico Nacional, SEPI-ESIME Unidad Azcapotzalco, Departamento de Termofluidos