Effect of particle transient motion on lubrication

Abstract

PurposeThe purpose of this paper is to analyze the influence of particle motion on the lubrication characteristics. The dynamics of the particle in the lubricant is also studied.Design/methodology/approachThe dynamics of the particle is studied using Newton's second law. The particle dynamic equation is solved to determine the particle velocity, angular velocity, and location. The modified Reynolds equation is solved in couple with particle motion to determine the film pressure and velocity.FindingsThe motion of a particle suspended in the lube oil is clarified. The initial relative velocity between the particle and the fluid has a significant effect on the lubrication. For the same particle location and velocity, the larger particle or the closer distance between particle center and lower plate has greater effects on the film pressure.Research limitations/implicationsThe influence of the particle geometry on the lubrication is neglected in the study because of the small size of the particle, this neglect is idealized. Further study will take the effects of the particle geometry into consideration.Originality/valueThe paper provides the motion of the particle in the lubricant, and the modified Reynolds equation considering the particle translation as well as rotation is derived.

Particle Entrapment in Line Elastohydrodynamic Contacts and the Influence of Intermolecular (van der Waals) Forces

“…This agrees with the theoretical analysis of Kang et al [6]. On the other side, smaller particles (e.g., less than 10 µm in diameter) that enter deeply inside the contact gap prior to touching the contact counter-surfaces and have approximately attained the local fluid velocity do not possess the size necessary to significantly upset the local surface deflection and alter the local geometry, which has been theoretically shown by Han et al [8]. Therefore, for the purpose of establishing the local surface geometry, it is rational to consider surfaces 1 and 2 as elastically undisturbed by the presence of a particle prior to it touching them.…”

“…If the particle is in contact with only one surface or is not in contact with any surface, then we are actually dealing with "entrainment". The latter involves a different theoretical analysis and has been treated in other studies (e.g., [4][5][6][7][8]), with emphasis on elastohydrodynamically lubricated (EHL) contacts. Interested readers are also directed to Section 6 of Nikas [1] for a literature review on the particular topic of particle entrainment, including rigorous mathematical studies in the context of fluid mechanics and/or granular flow analysis in the case of suspensions instead of one isolated particle.…”

Lubrication Model and Dynamic Characteristics of Distributed Liquid Film for Hydrodynamic Bearing

“…Therefore, the fluid-solid-thermal model is the dominant factor of the compressive model. However, it's difficult to build the definite solution model or get experimental verification for some factors which can affect the evolution and recession of bearings' performance, such as corrosion, wear [8], abrasive particles [9] and two-phase of gas-liquid [10] etc. Modifying factor or qualitative knowledge about law and criterion can be introduced in the dominant model.…”