Journal ArticleDOI
The Rheology and Hydrodynamic Analysis of Grease Flows in a Circular Pipe
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In this paper, the shear-rate dependent viscosities of two NLGI grade No. 2 greases, Grease A and Grease B, were measured using a capillary tube viscometer within a temperature range of 5°−35°C.Abstract:
The shear-rate dependent viscosities of two NLGI grade No. 2 greases, Grease A and Grease B, were measured using a capillary tube viscometer within a temperature range of 5°−35°C. The yield stresses of these greases were directly measured without extrapolation process as a function of temperature. Two types of the yield stresses were found to exist: one was a start-up yield stress below which grease does not start flowing, and the other was a stopping yield stress at which the grease stopped flowing. The former is substantially larger than the latter and should play an important role in the design of an automatic grease pumping system, a system normally operated in an intermittent mode rather than in a continuous mode. In general, the yield stress of Grease A increased with increasing temperatures whereas that of Grease B decreased with increasing temperatures. Continuous pumping tests with Grease A were conducted in four different diameter pipes. A new friction coefficient-Reynolds number correlation was...read more
Citations
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Journal ArticleDOI
Steady flow and viscoelastic properties of lubricating grease containing various thickener concentrations
TL;DR: The flow and viscoelastic properties of a lubricating grease formed from a thickener composed of lithium hydroxystearate and a high-boiling-point mineral oil were investigated as a function of thickener concentration and suggest that the flocculation of the particles that compose the grease is likely to be of the chemically limited aggregation variety.
Journal ArticleDOI
A method of isolating surface tension and yield stress effects in a U-shaped scanning capillary-tube viscometer using a Casson model
TL;DR: In this article, a U-shaped scanning capillary-tube viscometer (SCTV) was used to measure the viscosity of distilled water and bovine blood.
Journal ArticleDOI
Experimental study of grease flow in pipelines: wall slip and air entrainment effects
TL;DR: In this article, the Sisko model was applied in the experimental range of flow rates for predicting pressure drop gradient and evaluation of wall slip and air bubbles entrainment effects observed during the piping flow of lubricating greases.
Journal ArticleDOI
μPIV measurement of grease velocity profiles in channels with two different types of flow restrictions
Jinxia Li,Erik Höglund,Lars-Göran Westerberg,Torbjörn Green,T.S. Lundstrom,Pieter Martin Lugt,Pieter Baart +6 more
TL;DR: In this paper, the authors used a 2D flow model geometry consisting of a wide channel with rectangular cross-section and two different types of restrictions to measure the grease velocity vector field, using the method of Micro Particle Image Velocimetry.
Journal ArticleDOI
A rheological model for lithium lubricating grease
Meng Yonggang,Zheng Jie +1 more
TL;DR: In this paper, the rheological properties of a lithium lubricating grease were examined under various settings of shear rate, time and temperature with an emphasis on the thixotropy of grease.
References
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Journal ArticleDOI
The Rheology and Flow of Viscoplastic Materials
Journal ArticleDOI
The yield stress myth
Howard A. Barnes,Kenneth Walters +1 more
TL;DR: In this article, the simple Cross model is shown to be a useful empiricism for many non-Newtonian fluids, including those which have hitherto been thought to possess a yield stress.
Journal ArticleDOI
Thixotropy - a general review
TL;DR: In this paper, the evolution of the concept is traced back and a generalized definition is accepted, and various experimental methods are considered with which meaningful measurements of thixotropy can be performed.
Journal ArticleDOI
Phenomenological characterization of the rheological behaviour of inelastic reversible thixotropic and antithixotropic fluids
D C-H Cheng,F Evans +1 more
TL;DR: In this article, the constitutive equations for inelastic thixotropic fluids proposed by Moore and Hahn et al. and generalized into an equation of state F = η(λ, D)D and a rate equation dλ/dt = gD(λ and D) for both thixotropy and antithixotropic fluid were discussed.