Rheology of Dilute Polymer Solutions and Engine Lubricants in High Deformation Rate Extensional Flows Produced by Bubble Collapse

2004 ◽  
Vol 126 (2) ◽  
pp. 162-169 ◽  
Author(s):  
M. S. Barrow ◽  
S. W. J. Brown ◽  
S. Cordy ◽  
P. R. Williams ◽  
R. L. Williams
Keyword(s):  
Xanthan Gum ◽  
Extensional Flow ◽  
Journal Bearings ◽  
Bubble Collapse ◽  
Liquid Jets ◽  
Pressure Waves ◽  
Polymeric Additive ◽  
High Deformation Rate ◽  
High Deformation ◽  
Dilute Polymer Solutions

We report a study of liquid jets formed by the collapse of bubbles under cavitation-generated pressure waves. Such jets involve an extensional flow which is characterized by high rates of extension, the latter being relevant to considerations of the flow of oils within dynamically loaded journal bearings. The technique reported here is found to be sensitive to the influence of extremely small concentrations of high molecular weight polymeric additive (xanthan gum). Commercial multigrade oils are also found to exhibit significantly larger resistance to extensional flow than their Newtonian counterparts and, insofar as the multigrade oils studied here are made viscoelastic by polymer additives, and possess significant levels of resistance to extension, the results provide evidence in support of a mitigating effect of viscoelasticity on cavitation, as mooted by Berker et al. [3].

High Deformation Rate Uniaxial Elongation Flow of Mobile Fluids in Cavitation Bubble Collapse Experiments

2003 ◽  
Author(s):  
P. Rhodri Williams ◽  
Matthew S. Barrow ◽  
Stephen Cordy ◽  
Karl Hawkins
Keyword(s):  
Journal Bearing ◽  
Extensional Flow ◽  
Significant Degree ◽  
Bubble Collapse ◽  
High Deformation Rate ◽  
High Deformation ◽  
Uniaxial Elongation ◽  
Elongation Flow ◽  
Low Shear Viscosity ◽  
Low Shear

We report experimental work involving the rapid uniaxial elongation of jets of mobile (i.e. low shear viscosity) liquids formed by the collapse of a gas bubble under a cavitation-generated shockwave. The results of this work establish that the jets experience a significant degree of extensional deformation, at high rates of extension (typically > 1000 s−1) which are relevant to considerations of journal bearing lubrication. The results of experiments conducted on samples of commercial multigrade motor lubricants in the 15W40 category indicate a substantially increased resistance to extensional flow when compared with the behaviour of their Newtonian counterparts. Interestingly, the technique is able to distinguish between the rheological properties of lubricants of identical category (15W40) which are formulated for use in different engines (petrol engine and diesel engine, respectively). The lubricant formulated for the latter application is found to exhibit the highest resistance to extensional flow.

Rheology of Multigrade Engine Lubricants in High Deformation Rate Extensional Flow

2003 ◽  
Author(s):  
S. Cordy ◽  
M. S. Barrow ◽  
S. W. J. Brown ◽  
K. Hawkins ◽  
P. R. Williams
Keyword(s):  
Deformation Rate ◽  
Extensional Flow ◽  
High Deformation Rate ◽  
High Deformation

Extensional Flow of Xanthan Gum Solutions

1985 ◽  
Vol 29 (2) ◽  
pp. 191-207 ◽  
Author(s):  
M. Khagram ◽  
R. K. Gupta ◽  
T. Sridhar
Keyword(s):  
Xanthan Gum ◽  
Extensional Flow

Cinematographic Analysis of Counter Jet Formation in a Single Cavitation Bubble Collapse Flow

2011 ◽  
Vol 27 (2) ◽  
pp. 253-266 ◽  
Author(s):  
S.-H. Yang ◽  
S.-Y. Jaw ◽  
K.-C. Yeh
Keyword(s):  
Flow Field ◽  
Cavitation Bubble ◽  
Pressure Wave ◽  
Bubble Surface ◽  
Bubble Collapse ◽  
Solid Boundary ◽  
Liquid Jet ◽  
Pressure Waves ◽  
Field Variation ◽  
Critical Position

ABSTRACTThis study utilized a U-shape platform device to generate a single cavitation bubble for the detail analysis of the flow field characteristics and the cause of the counter jet during the process of bubble collapse induced by pressure wave. A series of bubble collapse flows induced by pressure waves of different strengths are investigated by positioning the cavitation bubble at different stand-off distances to the solid boundary. It is found that the Kelvin-Helmholtz vortices are formed when the liquid jet induced by the pressure wave penetrates the bubble surface. If the bubble center to the solid boundary is within one to three times the bubble's radius, a stagnation ring will form on the boundary when impacted by the penetrated jet. The liquid inside the stagnation ring is squeezed toward the center of the ring to form a counter jet after the bubble collapses. At the critical position, where the bubble center from the solid boundary is about three times the bubble's radius, the bubble collapse flows will vary. Depending on the strengths of the pressure waves applied, either just the Kelvin-Helmholtz vortices form around the penetrated jet or the penetrated jet impacts the boundary directly to generate the stagnation ring and the counter jet flow. This phenomenon used the particle image velocimetry method can be clearly revealed the flow field variation of the counter jet. If the bubble surface is in contact with the solid boundary, the liquid jet can only splash radially without producing the stagnation ring and the counter jet. The complex phenomenon of cavitation bubble collapse flows are clearly manifested in this study.

Investigating the confining compressibility of STF at high deformation rate

2012 ◽  
Vol 60 (3) ◽  
pp. 31101 ◽  
Author(s):  
Weifeng Jiang ◽  
Xinglong Gong ◽  
Yulei Xu ◽  
Shouhu Xuan ◽  
Wanquan Jiang ◽  
...  
Keyword(s):  
Deformation Rate ◽  
High Deformation Rate ◽  
High Deformation

On the hysteretic behaviour of dilute polymer solutions in relaxation following extensional flow

1999 ◽  
Vol 82 (2-3) ◽  
pp. 233-253 ◽  
Author(s):  
R. Sizaire ◽  
G. Lielens ◽  
I. Jaumain ◽  
R. Keunings ◽  
V. Legat
Keyword(s):  
Polymer Solutions ◽  
Extensional Flow ◽  
Hysteretic Behaviour ◽  
Dilute Polymer Solutions

scholarly journals Effect of Hot Deformation Temperature on Texture Formation Regularity of CGO Silicon Steel under High Deformation Rate

2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
Zhi-chao Li ◽  
Ning Dang ◽  
Zhen-li Mi
Keyword(s):  
Hot Deformation ◽  
Deformation Rate ◽  
Deformation Temperature ◽  
Room Temperature ◽  
Silicon Steel ◽  
High Deformation Rate ◽  
Goss Texture ◽  
High Deformation ◽  
Increasing Trend ◽  
Pearlite Content

The influence of hot deformation temperature on microstructure and texture of CGO silicon steel under the condition of a high deformation rate (100 s-1) was studied by SEM and EBSD techniques. The results indicate that the typical microstructures at room temperature consist of ferrite and pearlite under different hot deformation temperatures. The higher deformation temperature is beneficial to obtain a more uniform recrystallization microstructure and lower pearlite content. Cubic texture{100}001and rotated cubic texture{100}011are dominant texture components in the tested steels, and{111}112texture inγfiber is also strong, the intensity of which is higher than that of{111}110texture. Goss texture{110}001is weak. With the rising of the hot deformation temperature,{100}011texture decreases firstly and then increases at 1100°C. When the hot deformation temperature raises from 800°C to 900°C,{111}112texture shows an increasing trend, while{111}110texture content is stable. When the temperature further increases to 1100°C and 1150°C,{111}112and{111}110textures are slightly weakened.

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