High-frequency forcing of a turbulent axisymmetric wake
High-frequency forcing of a turbulent axisymmetric wake
复制标题
湍流轴对称尾流的高频强迫
DOI：
10.1017/jfm.2015.153
复制
发表时间：
2015
影响因子：
3.7
通讯作者：
Oxlade A
中科院分区：
文献类型：
--
作者：
Oxlade A
一个高频周期性射流，在分离点的正下方发出，被用来迫使海崖轴对称物体的湍流尾流，其轴线与自由流对齐。结果表明，底部压力可以改变或多或少的意志：在强迫频率的剪切层频率的几倍，时间平均面积加权的底部压力增加多达35%。利用随机和锁相的二分量粒子图像测速技术（PIV）研究了强迫效应，并在此基础上对压力脉动进行了模态分解。强迫并不针对特定的局部或全局尾流不稳定性：相反，高频射流产生一排紧密间隔的涡环，紧邻涡环的是每一侧的大剪切区域。这些剪切层与大的耗散相关联，并且抑制流体的夹带。由此产生的压力恢复是成比例的涡流的强度，并伴随着与所有模式相关联的基础压力波动的宽带抑制。剪切层模态放大接近单位增益时的最佳强迫频率大约是剪切层频率的五倍。
A high-frequency periodic jet, issuing immediately below the point of separation, is used to force the turbulent wake of a bluff axisymmetric body, its axis aligned with the free stream. It is shown that the base pressure may be varied more or less at will: at forcing frequencies several times that of the shear layer frequency, the time-averaged area-weighted base pressure increases by as much as 35 %. An investigation of the effects of forcing is made using random and phase-locked two-component particle image velocimetry (PIV), and modal decomposition of pressure fluctuations on the base of the model. The forcing does not target specific local or global wake instabilities: rather, the high-frequency jet creates a row of closely spaced vortex rings, immediately adjacent to which are regions of large shear on each side. These shear layers are associated with large dissipation and inhibit the entrainment of fluid. The resulting pressure recovery is proportional to the strength of the vortices and is accompanied by a broadband suppression of base pressure fluctuations associated with all modes. The optimum forcing frequency, at which amplification of the shear layer mode approaches unity gain, is roughly five times the shear layer frequency.
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影响因子：
3.7
作者：
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DOI：
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发表时间：
1981
期刊：
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通讯作者：
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DOI：
--
发表时间：
2009
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