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首页> 外文会议>Selected Papers from the 9th International Symposium on Laser Techniques Applied to Fluid Mechanics Lisbon, Portugal, July 13-16, 1998 >IV.I. Analysis of orderliness in higher instabilities toward the occurence of chaos in a taylor-courette flow system
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IV.I. Analysis of orderliness in higher instabilities toward the occurence of chaos in a taylor-courette flow system

机译：IV.I.泰勒－库埃特流动系统中发生混沌的更高不稳定性的有序性分析

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The purpose of the experimental work is to elucidate the mechanism for the occurrence of chaos in a Taylor-Couette flow system. The attention was focused on the higher instability region from the doubly-periodic to the weakly-turbulent wavy vortex flow. In order to take note of the effect of hysteresis, the inner cylinder rotation was accelerated at a constant rate from rest unitl a specified Reynolds number was reached. The test section with the radius ratio of 0.625 had an annular gap width of 22.5 mm and an aspect ratio of 4. A fiberoptic laser-Doppler velocimenter was employed to observe a time-dependent, peripheral component of velocity at the central rgion of vortex cells. At the same time, time-dependent peripheral component of velocity gradients on the wall of the stationary outer cylinder were measured in the neighborhood of one of the outflow cell boundaries with a hot-film shear sensor embedded flush with the inside cylindrical surface. Four votex cells were always formed regardless of the acceleration rate of the inner cylinder rotation tested in the start-up operation, but the axial wavelenth of the two central vortices was shorter than that of the remaining two end vortices. The amplitudes of the fluctuations of velocity and velocity-gradient varied irregularly whereas the first fundamental frequency was maintained in proportion to the inner cylinder rotation as long as the azimuthally-traveling waves existed. It has been concluded that chaos occurs firstly at the inflow cell boundaries as a result of instability in the viscous interaction of end vortices with the fiexed bottom and top surfaces and that the chaotic turbulence is propagated along the secondary flow streamlines toward the central votices and penetrated very slowly toward the center of vortex cells.
机译：实验工作的目的是阐明泰勒-库埃特流动系统中发生混沌的机理。人们的注意力集中在从双周期到微湍流的波浪涡流的较高的不稳定性区域。为了注意到磁滞的影响，内筒旋转从静止单元开始以恒定速率加速，达到了指定的雷诺数。半径比为0.625的测试部分的环形间隙宽度为22.5 mm，长径比为4。使用光纤激光多普勒测速仪观察涡旋细胞中心区域的速度随时间变化的外围分量。同时，在固定在外圆筒壁上的速度梯度的随时间变化的外围分量，在流出单元边界之一附近，通过与内圆筒表面齐平嵌入的热膜剪切传感器进行测量。无论在启动操作中测试的内圆柱旋转的加速率如何，始终会形成四个voetx单元，但是两个中心涡流的轴向波长比其余两个端涡旋的轴向波长要短。速度和速度梯度的波动幅度不规则变化，而只要存在方位行进波，第一基本频率就与内圆柱旋转成比例地保持不变。已经得出结论，首先由于末端涡流与狭窄的底部和顶部表面之间的粘性相互作用的不稳定性，首先在流入单元的边界处发生混沌，并且混沌湍流沿次要流线向中央涡流传播并渗透。非常缓慢地向漩涡细胞的中心移动。

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