Stability of Non-Newtonian Taylor-Couette With Axial Flow
Stability of Non-Newtonian Taylor-Couette With Axial Flow
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DOI：
10.1115/imece2011-63067
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
N. Ashrafi;A. Hazbavi
中科院分区：
文献类型：
--
作者：
N. Ashrafi;A. Hazbavi
轴向流对泰勒-库埃特流稳定性的影响适用于剪切稀化流体。假设流体遵循 Carreau-Bird 模型，并施加混合边界条件。四维低阶动力系统由质量守恒和动量方程的伽辽金投影得出，在速度分量中包括源自剪切相关粘度的附加非线性项。在没有轴向流的情况下，随着剪切稀化效应的增加，基流在较低的临界泰勒数下失去了涡流结构的径向流稳定性。涡流的出现对应于超临界分叉的开始，这也可以在线性流体的流动中看到。然而，与牛顿情况不同，当泰勒数达到与霍普夫分岔开始相对应的第二临界数时，剪切稀化泰勒涡旋就会失去稳定性。由压力梯度体现的轴流的存在似乎进一步推进了分叉图上的每个临界点。分叉图中给出了不同情况下的完整流场和粘度图。版权所有 © 2011 by ASME
The influence of axial flow on stability of the Taylor-Couette flow is carried for shear thinning fluids. The fluid is assumed to follow the Carreau-Bird model and mixed boundary conditions are imposed. The four-dimensional low-order dynamical system, resulted from Galerkin projection of the conservation of mass and momentum equations, includes additional nonlinear terms in the velocity components originated from the shear-dependent viscosity. In absence of axial flow the base flow loses its radial flow stability to the vortex structure at a lower critical Taylor number, as the shear thinning effects increases. The emergence of the vortices corresponds to the onset of a supercritical bifurcation which is also seen in the flow of a linear fluid. However, unlike the Newtonian case, shear-thinning Taylor vortices lose their stability as the Taylor number reaches a second critical number corresponding to the onset of a Hopf bifurcation. Existence of an axial flow, manifested by a pressure gradient appears to further advance each critical point on the bifurcation diagram. Complete flow field together with viscosity maps are given for different scenarios in the bifurcation diagram.Copyright © 2011 by ASME