Researching and Modeling of the Dynamic Viscosity of the Ferro-Oils With the Different Concentrations of Magnetic Particles in the Aspect of Pressure Changes

Abstract

In this article, the results of the experimental research of determining the dynamic viscosity of the ferro-oils with different concentration of the magnetic particles in terms of pressure change are presented. The research was conducted on the Thermo Scientific Haake Mars III rheometer in the configuration with a pressure chamber. The applied configuration allowed the author to conduct research on the change of viscosity for the selected pressure values p in range from 0 to 100 bars. The research was conducted for three selected temperature values, including t = 30°C, 60°C, and 90°C, as well as selected shear rates of 200 and 600s-1. The chosen concentration values of the magnetic particles were nCS = 1%, 2%, 4%, 6%, and 8%. The viscous characteristics gathered as a result of the research have been analysed with the aim of identifying the nature of the correlations and to create mathematical-physical models of changes in the dynamic viscosity of the ferrooils due to the change in pressure in terms of concentrations of the magnetic particles. Analysis, identification, and adaptation of the characteristics were conducted using the StatSoft STATISTICA ver. 9 software. Selected mathematical adaptations of the acquired results were submitted through the enhanced analysis. In addition, parameters of the course of functions were designated and their qualitative assessments were made.

Distributions of Hydrodynamic Pressure in the Gap of Slide Journal Bearing Lubricated with Ferro-Oil

“…The constitutive equation for ferro-oil was adopted from non-Newtonian viscoelastic model of Rivlin-Ericksen' fluid [13,16,17]. The dependence of the dynamic viscosity of ferro-oil on magnetic induction, temperature and pressure was taken into account η = η(B, T, p) [2,3,8,10], whereas material factors α, β were assumed to be constant.…”

“…and p = pat as well as values of magnetic susceptibility coefficients of a ferro-oil have been determined experimentally [9] and their adopted values [2,3,8,10] There have been adopted the following dimensional and dimensionless quantities for all calculations of operational parameters: a low-speed bearing with an angular velocity of the journal ω = 20 s -1 was assumed; the journal radius was R = 0.15 m and the dimensionless bearing length L1 = 1; a constant dimensionless radial relative clearance value ψ = 0.003 has been adopted; the ferro-oil thermal conduction coefficient was established as unchangeable and was equal κ = 0.15; the material coefficients of a ferro-oil were respectively: α = 0.000020 and β = -0.000010; the value of the magnetic field intensity vector was assumed at the level ensuring full magnetic saturation of a ferro-oil Ho = 280000 A⋅m -1 [9]. In the calculations carried out, it was assumed that the bearing placement effect will not be taken into account in the model, hence the misalignment angle was γ = 0º.…”

“…The first of them is a derivative of the modification that the base oil undergoes with the addition of both magnetically susceptible particles and surfactant. These modifiers make the ferrooil begins to exhibit, in addition to the classical viscosity of the oil depending on the pressure and temperature [2,3] dependence of viscosity on shear rate [4]. These additives increase the viscosity of the ferro-oil relative to the base lubricating liquid.…”