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Taylor-Couette Flow Control Using Inner Cylindre Cross-Section Variation Strategy

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Document pages: 10 pages

Abstract: The socalled Taylor–Couette flow is involved in several promising technologies such as heat exchangers, cooling systems, hydrocarbon drilling and reactors to produce uniform ultra-fine particles. Entrapped by Taylor structures and concentrated in the core of the vortices. This leads to an adverse impact on producing uniformly distributed particles. To remedy, an active flow control strategy is developed to ensure complete disappearance of the Taylor vortices in the whole system. To this aim, a numerical study is developed to simulate such a controlled flow.The suggested strategy relies on the inner cylinder cross-section variation according to a pre-defined sinus law. Simulations are carried out on the Fluent software package based on the finite-volume method for a three-dimensional incompressible flow. The basic system geometry is characterized by a height H= 150 mm, ratio of the inner to outer cylinder radii η= 0.9, a radial gap δ= 0.11 and an aspect ratio corresponding to the cylinder height reported to the gap length Г= 15. In a first step, and for the natural (non-controlled) case of the flow it is attempted to follow the early flow genesis stages since Ekman cells onset at very low Taylor number (Ta=10-6) to the first instability settlement. The obtained results show that the Ekman structures are already detected for a Taylor number as low as Ta=10-5 as local pressurized zones regularly distributed on the inner cylinder surface with π 2 phase lag. The numerical deformation of the inner cylinder is executed using the dynamic mesh tool via an UDF (User Defined Function). It is established that the first instability is retarded from Tac1 = 43.8 to Tac1= 50 when ε= 0.8 and ƒ = 1Hz and from Tac1= 43.8 to Tac1= 54 when ε= 0.1 and ƒ = 20Hz, and a kinetic energy increase with deforming amplitude increasing.

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