scholarly journals Numerical study of heat flow characteristics of turbulent Taylor-Couette flow in slit wall mode

2021 ◽  
Vol 9 ◽  
Author(s):  
Dong Liu ◽  
◽  
Mohammed Mohammedsalih ◽  
Amponsah-Gyenin Nana Kofi ◽  
Shi-cheng Ding ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Couette Flow ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Simulation Method ◽  
Industrial Applications ◽  
Small Scale ◽  
Taylor Couette ◽  
Taylor Couette Flow

Heat transfer enhancement is by far an important component in the design of numerous industrial applications of Taylor-Couette flow including electric motors and particularly rotating machinery. To optimize the performances of these machines, superior knowledge of the fluid flow is vital to better estimate the heat transfer distribution. This study will specifically consider the effect the slit number and width possess on the distribution of turbulent Taylor-Couette flow and the resulting heat transfer correlation in the annulus of two concentric cylinders under varying conditions. A numerical simulation method is intended for the study using varying slit structure parameters of widths (2.5 ≤ w ≤ 7.5) mm and fitted with 6, 9 and 12 number of slits. The slit effect is then investigated under both isotherm and non-isotherm conditions considering the interactions between fluid flow regions in the mainstream area and the annulus. The small-scale vortex that appears in the annulus region improves the heat transferability between the fluid in the annulus and the main region as well as the heat transfer performance of the model with a gradual increase in Reynolds number.

scholarly journals Scalable Exfoliation of Bulk MoS2 to Single- and Few-Layers Using Toroidal Taylor Vortices

Nanomaterials ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 587 ◽  
Author(s):  
Vishakha Kaushik ◽  
Shunhe Wu ◽  
Hoyoung Jang ◽  
Je Kang ◽  
Kyunghoon Kim ◽  
...  
Keyword(s):  
Couette Flow ◽  
Flow Reactor ◽  
Batch Process ◽  
Industrial Applications ◽  
Shear Stresses ◽  
Mos2 Nanosheets ◽  
Taylor Vortices ◽  
Taylor Couette ◽  
Bulk Mos2 ◽  
Taylor Couette Flow

The production of a large amount of high-quality transition metal dichalcogenides is critical for their use in industrial applications. Here, we demonstrate the scalable exfoliation of bulk molybdenum disulfide (MoS2) powders into single- or few-layer nanosheets using the Taylor-Couette flow. The toroidal Taylor vortices generated in the Taylor-Couette flow provide efficient mixing and high shear stresses on the surfaces of materials, resulting in a more efficient exfoliation of the layered materials. The bulk MoS2 powders dispersed in N-methyl-2-pyrrolidone (NMP) were exfoliated with the Taylor-Couette flow by varying the process parameters, including the initial concentration of MoS2 in the NMP, rotation speed of the reactor, reaction time, and temperature. With a batch process at an optimal condition, half of the exfoliated MoS2 nanosheets were thinner than ~3 nm, corresponding to single to ~4 layers. The spectroscopic and microscopic analysis revealed that the exfoliated MoS2 nanosheets contained the same quality as the bulk powders without any contamination or modification. Furthermore, the continuous exfoliation of MoS2 was demonstrated by the Taylor-Couette flow reactor, which produced an exfoliated MoS2 solution with a concentration of ~0.102 mg/mL. This technique is a promising way for the scalable production of single- or few-layer MoS2 nanosheets without using hazardous intercalation materials.

Heat Transfer Enhancement in Axial Taylor-Couette Flow

2005 ◽  
Author(s):  
S. Gilchrist ◽  
C. Y. Ching ◽  
D. Ewing
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Couette Flow ◽  
Reynolds Numbers ◽  
Taylor Number ◽  
Number Range ◽  
Taylor Couette ◽  
Number Case ◽  
Taylor Couette Flow

An experimental investigation was performed to determine the effect that surface roughness has on the heat transfer in an axial Taylor-Couette flow. The experiments were performed using an inner rotating cylinder in a stationary water jacket for Taylor numbers of 106 to 5×107 and axial Reynolds numbers of 900 to 2100. Experiments were performed for a smooth inner cylinder, a cylinder with two-dimensional rib roughness and a cylinder with three-dimensional cubic protrusions. The heat transfer results for the smooth cylinder were in good agreement with existing experimental data. The change in the Nusselt number was relatively independent of the axial Reynolds number for the cylinder with rib roughness. This result was similar to the smooth wall case but the heat transfer was enhanced by 5% to 40% over the Taylor number range. The Nusselt number for the cylinder with cubic protrusions exhibited an axial Reynolds number dependence. For a low axial Reynolds number of 980, the Nusselt number increased with the Taylor number in a similar way to the other test cylinders. At higher axial Reynolds numbers, the heat transfer was initially independent of the Taylor number before increasing with Taylor number similar to the lower Reynolds number case. In this higher axial Reynolds number case the heat transfer was enhanced by up to 100% at the lowest Taylor number of 1×106 and by approximately 35% at the highest Taylor number of 5×107.

Heat Transfer in a Taylor-Couette Flow

2017 ◽  
Author(s):  
Vinicius Malatesta ◽  
Vinícius Hagemeyer Chiumento
Keyword(s):  
Heat Transfer ◽  
Couette Flow ◽  
Taylor Couette ◽  
Taylor Couette Flow

Modulation of elasto-inertial transitions in Taylor–Couette flow by small particles

2021 ◽  
Vol 929 ◽  
Author(s):  
Tom Lacassagne ◽  
Theofilos Boulafentis ◽  
Neil Cagney ◽  
Stavroula Balabani
Keyword(s):  
Couette Flow ◽  
Volume Fraction ◽  
Industrial Applications ◽  
Laminar Flows ◽  
Particle Suspensions ◽  
Constant Viscosity ◽  
Taylor Couette ◽  
Spatio Temporal ◽  
Flow Transitions ◽  
Taylor Couette Flow

Particle suspensions in non-Newtonian liquid matrices are frequently encountered in nature and industrial applications. We here study the Taylor–Couette flow (TCF) of semidilute spherical particle suspensions (volume fraction $\leq 0.1$ ) in viscoelastic, constant-viscosity liquids (Boger fluids). We describe the influence of particle load on various flow transitions encountered in TCF of such fluids, and on the nature of these transitions. Particle addition is found to delay the onset of first- and second-order transitions, thus stabilising laminar flows. It also renders them hysteretic, suggesting an effect on the nature of bifurcations. The transition to elasto-inertial turbulence (EIT) is shown to be delayed by the presence of particles, and the features of EIT altered, with preserved spatio-temporal large scales. These results imply that particle loading and viscoelasticity, which are known to destabilise the flow when considered separately, can on the other hand compete with one another and ultimately stabilise the flow when considered together.

Numerical Simulations of Heat Transfer in Taylor-Couette Flow

1998 ◽  
Vol 120 (1) ◽  
pp. 65-71 ◽  
Author(s):  
R. Kedia ◽  
M. L. Hunt ◽  
T. Colonius
Keyword(s):  
Heat Transfer ◽  
Numerical Simulations ◽  
Couette Flow ◽  
Stokes Equations ◽  
Taylor Vortex ◽  
Cylinder Surface ◽  
Stable States ◽  
Grashof Number ◽  
Taylor Couette ◽  
Taylor Couette Flow

Numerical simulations have been performed to study the effects of the gravitational and the centrifugal potentials on the stability of heated, incompressible Taylor-Couette flow. The flow is confined between two differentially heated, concentric cylinders, and the inner cylinder is allowed to rotate. The Navier-Stokes equations and the coupled energy equation are solved using a spectral method. To validate the code, comparisons are made with existing linear stability analysis and with experiments. The code is used to calculate the local and average heat transfer coefficients for a fixed Reynolds number (Re = 100) and a range of Grashof numbers. The investigation is primarily restricted to radius ratios 0.5 and 0.7 for fluids with Prandtl number of about 0.7. The variation of the local coefficients of heat transfer on the cylinder surface is investigated, and maps showing different stable states of the flow are presented. Results are also presented in terms of the equivalent conductivity, and show that heat transfer decreases with Grashof number in axisymmetric Taylor vortex flow regime, and increases with Grashof number after the flow becomes nonaxisymmetric.

scholarly journals Direction reversal of a rotating wave in Taylor–Couette flow

2008 ◽  
Vol 607 ◽  
pp. 199-208 ◽  
Author(s):  
J. ABSHAGEN ◽  
M. HEISE ◽  
Ch. HOFFMANN ◽  
G. PFISTER
Keyword(s):  
Aspect Ratio ◽  
Couette Flow ◽  
Numerical Study ◽  
Propagation Speed ◽  
Vortex State ◽  
Mean Flow ◽  
Rotating Wave ◽  
Taylor Couette ◽  
Direction Reversal ◽  
Taylor Couette Flow

In Taylor–Couette systems, waves, e.g. spirals and wavy vortex flow, typically rotate in the same direction as the azimuthal mean flow of the basic flow which is mainly determined by the rotation of the inner cylinder. In a combined experimental and numerical study we analysed a rotating wave of a one-vortex state in small-aspect-ratio Taylor–Couette flow which propagates either progradely or retrogradely in the inertial (laboratory) frame, i.e. in the same or opposite direction as the inner cylinder. The direction reversal from prograde to retrograde can occur at a distinct parameter value where the propagation speed vanishes. Owing to small imperfections of the rotational invariance, the curves of vanishing rotation speed can broaden to ribbons caused by coupling between the end plates and the rotating wave. The bifurcation event underlying the direction reversal is of higher codimension and is unfolded experimentally by three control parameters, i.e. the Reynolds number, the aspect ratio, and the rotation rate of the end plates.

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