Investigation of Grease Flow in a Rectangular Channel Including Wall Slip Effects Using Microparticle Image Velocimetry

Westerberg, Lars G.; Lundström, T. Staffan; Höglund, Erik; Lugt, Piet M.

doi:10.1080/10402001003605566

Cited by 31 publications

(47 citation statements)

References 12 publications

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“…The greases considered are Lithium complex greases with density of 880-1070 kg/m 3 , service temperature -40ºC to 150ºC, and drop point < 220ºC. They are similar to the greases studied in Westerberg et al [17] where the flow properties and its relation to the rheology of the grease was investigated, showing a complex semi-solid behavior. The actual grease properties allowed the grease to remain in the position where it is injected; in this case the tooth flank, but it's fluency through the proposed micro-nozzle should be verified.…”

Section: Grease Fluency Studymentioning

confidence: 95%

New method for lubricating wind turbine pitch gears using embedded micro-nozzles

2017

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Aquesta és una còpia de la versió author's final draft d'un article publicat a la revista Journal of mechanical science and technology.La publicació final està disponible a Springer a través de http://dx.doi.org/10.1007/s12206-017-0131-3 This is a copy of the author 's final draft version of an article published in the journal Journal of mechanical science and technology. --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- AbstractThe increase of power generated by wind turbines has increased the stresses applied in all of its parts, which causes the appearance of premature failures. In particular, pitch and yaw gears suffer of excessive wear, mainly due to inappropriate lubrication. This paper presents a novel method to automatically lubricate the wind turbine pitch gear during operation. A micro-nozzle to continuously inject fresh grease between the teeth in contact was designed, manufactured and installed in a test bench of a 2 MW wind turbine pitch system. The test bench was used to characterize the fatigue behavior of the gear surface using conventional wind turbine greases under real cyclic loads. The measurements of wear evolution in a pitch gear with and without micro-nozzle show a decrease of 70% of the wear coefficient after 2x10 4 cycles.

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Section: Grease Fluency Studymentioning

confidence: 95%

New method for lubricating wind turbine pitch gears using embedded micro-nozzles

2017

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“…Radulescu et al [24] investigated the flow in pipes with discontinuities, which also could be applied to the flow in bearings. This work is a continuation of previous studies of the flow in closed straight channels [29,17] and in a 3D double restriction seal geometry [14,1,18]. A channel with a 90 • elbow is used and an analytical model of the flow is developed and combined with experimental data from micro Particle Image Velocimetry (µPIV) measurements of the flow in the elbow.…”

Section: Introductionmentioning

confidence: 97%

“…The elbow section channel have an inner/outer radius of 0.875/1.125 mm. For a corresponding model of the flow in the straight sections the reader is referred to the work by Westerberg et al [29]. The flow is considered incompressible and the velocity u is considered to only have a component in the ϕ-direction and only be dependent on the radial position, i.e.…”

Section: Analytical Model Of the Flow In The Channel Elbowmentioning

confidence: 99%

“…The velocity profile has in the presence of wall slip three characteristic regions in connection to each boundary, going from respective boundary towards the middle of the elbow [29]: a very thin slip layer, a viscous region where the grease is fully yielded, i.e. |τ | > τ 0 , and a plug region where the grease behaves as a solid body |τ | < τ 0 .…”

Section: R ∂ ∂Rmentioning

confidence: 99%

“…However, if slip is present the no slip condition is no longer valid. Following the methodology presented in Westerberg et al [29] the velocity data point being located closest to the channel wall is considered as boundary condition in this paper (u 1 in Fig. 2).…”

Section: R ∂ ∂Rmentioning

confidence: 99%

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Grease flow in an elbow channel

Westerberg

Farré-Lladós

et al. 2015

Tribol Lett

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Lubricating greases are materials characterized by a complex nonNewtonian rheology. This study is a continuation of previous studies on the coupling between grease rheology and grease flow in a straight channel-and concentric cylinder geometry. The problem has been modeled and validated with experiments. Here the flow in an elbow channel introducing a non-symmetric distribution of shear stress throughout the cross section of the channel elbow, as well as varying shear rates through the transition from the channel inlet to the outlet. The flow has been modeled both for higher flow rates and for creep flow. The influence of the grease rheology and flow conditions to wall slip, shear banding and an observed stick-slip type of motion observed for low flow rates are presented. The effect on the flow of the applied pressure is also investigated showing that the flow is sensitive to the pressure in the angular (ϕ) direction of the elbow. For high flow rates it is shown that flow separation occur with a resulting circulation in the elbow.

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2012

Grease Lubrication in Rolling Bearings

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Investigation of Grease Flow in a Rectangular Channel Including Wall Slip Effects Using Microparticle Image Velocimetry

Cited by 31 publications

References 12 publications

New method for lubricating wind turbine pitch gears using embedded micro-nozzles

New method for lubricating wind turbine pitch gears using embedded micro-nozzles

Grease flow in an elbow channel

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