CONTROL OF TURBULENT FLOWS USING LORENTZ FORCE ACTUATION
CONTROL OF TURBULENT FLOWS USING LORENTZ FORCE ACTUATION
复制标题
使用洛伦兹力驱动控制湍流
DOI：
10.1142/9789812700896_0011
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发表时间：
2005
影响因子：
3.7
通讯作者：
K. Breuer
中科院分区：
文献类型：
--
作者：
K. Breuer
我们讨论了使用电流体动力“洛伦兹力”作动器来影响低雷诺数完全湍流槽道流动的近壁流动。由于磁场和电流密度之间的相互作用，致动器诱导流体运动。这种作用力产生的跨向速度剖面对水流的穿透深度为几毫米，最大速度约为4厘米/S。虽然执行器能有效地在流动中产生扰动，但其效率较低，使其在工程系统中的实际应用受到怀疑。该激励器被用于完全湍流的低雷诺数槽道流动中，并用湍流阻力的直接测量和粒子图像测速仪测量了它们对湍流结构的影响。结果表明，在最佳条件下，阻力可减少约10%。同样，平均速度分布和脉动速度分布的PIV测量表明，某些振幅和频率组合对抑制湍流脉动和雷诺应力是有效的。在这些条件下，产生了局部加速的速度剖面。两点速度关联表明，强迫的作用是减小近壁相干结构的流向尺度，并大幅降低产生高振幅湍流“猝发”的频率。
We discuss the use of electro-hydrodynamic “Lorentz force” actuators to affect the near-wall flow of a low Reynolds number of a fully turbulent channel flow. The actuators induce fluid motion due to the interaction between a magnetic field and a current density. The force generates spanwise velocity profiles with a penetration depth into the flow of a few millimeters and maximum velocities of approximately 4 cm/s. Although the actuators are effective in generating disturbances in the flow, their efficiency is poor, making their practical use in engineering systems doubtful. The actuators are used in a fully turbulent low Reynolds number channel flow and their effect on the structure of the turbulent flow is measured using both a direct measurement of turbulent drag and Particle Image Velocimetry. Drag is shown to be reduced by approximately 10% at an optimal condition. Similarly, PIV measurements of the mean and fluctuating velocity profiles indicate that certain amplitude and frequency combinations are effective in suppressing the turbulent fluctuations and Reynolds stresses. At these conditions, a locally-accelerated velocity profile is generated. Two-point velocity correlations indicate that the effect of forcing is to reduce the streamwise scale of the near-wall coherent structures and to sharply reduce the frequency of high-amplitude turbulence-producing “bursts”.