Shear Thinning Biopolymers Fluids in a Taylor-Couette Flow
Creators: Baessa, Muaadh Ali
Publisher: name: University of Alberta Library
Year: 2022

<p>The current study investigates the effect of shear thinning rheology characteristics of high<br>
viscosity non-Newtonian biopolymers on the flow regime characterizations in Taylor Couette<br>
flow. The rheology measurements were carried out to investigate the viscoelastic properties of the<br>
biopolymers prior to the flow visualization experiments.<br>
Both concentrated xanthan gum (XG) and guar gum (GG) solutions were used in this study to<br>
investigate their pseudoplastic rheology properties in aqueous solutions over various ranges of<br>
concentrations from 0.1%wt to 4%wt. The flow curve and viscoelastic frequency sweep<br>
experiments were used to study the rheology of the concentrated biopolymers. The flow curve was<br>
performed over the shear rate range of 0.1 s- 1 to 100 s-1 whereas the frequency sweep was<br>
performed over the frequency of 0.1 to 300 rad/s. The rheology experiments were performed using<br>
a cylindrical head rheometer manufactured by Anton Paar model number NCR-302.<br>
The effect of storage time on the solution viscosity and yield stress of both solutions for the<br>
concentration of 1%wt was also investigated, with successive viscosity and yield stress stability<br>
progress obtained after performing the experiments at the end of each week and after up to 4 weeks<br>
of storage period. Additionally, an extra agitation time was applied for the solutions, and it was<br>
evaluated three different times 8 h, 24 h, and 48 h of continuous agitation time.<br>
After the rheology analysis, the flow visualization investigations experiments using a Taylor<br>
Couette system were performed, aiming to study the flow transition characteristics in the Taylor<br>
Couette system with a fixed outer cylinder and a rotating inner cylinder. The experiments focused<br>
on the flow mapping structure at the onset of each bifurcation for non-Newtonian solutions. We<br>
link the flow characterization transition of the shear thinning solutions in the Taylor Couette flow<br>
to the viscoelastic and yield stress properties obtained from the rheology analysis for each<br>
concentrated solution. Additionally, the flow mapping experiment aims to investigate the effect<br>
of the rheology viscoelastic properties such as the shear thinning flow index (n) on the flow<br>
mapping main parameters such as critical Reynolds number Re, and the azimuthal variations in<br>
the vortex wavelength and vortex count.<br>
The Taylor Couette (TC) flow system has numerous applications which depend on the concept of<br>
a rotating inner cylinder, including science, engineering, industrial, and fluid processes<br>
applications. The TC system is of great interest in the oil field where understanding in needed of<br>
the viscoelastic properties of the non-Newtonian fluids that are used as drilling. Additives may3 | Page<br>
contribute to the transport of sediments outside the well, by using inducing high viscous muds.<br>
The Taylor Couette system is a proper prototype to conduct experiments similar to the downhole<br>
walls and rotating string by considering the borehole wall as the outer cylinder and the rotating<br>
string as the inner cylinder. Additionally, the Taylor Couette system is also observed in various<br>
types of engineering applications, including journal-bearing lubrication, cooling of rotating<br>
machinery among others, and purification of industrial wastewater.</p>