Formation of vortex dipoles
Formation of vortex dipoles
复制标题
涡旋偶极子的形成
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
Y. Afanasyev
中科院分区：
文献类型：
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作者：
Y. Afanasyev
本文对有限尺寸喷管射流诱导的二维流动演化进行了实验研究。在发展流的前部形成涡偶极子，而在涡偶极子的后部形成尾喷流。使用粒子图像测速技术获得的涡量和速度场的详细测量的基础上，讨论了流动的动力学。结果发现，偶极子不分离（夹断）从尾喷流的值的冲程比高达15，这一事实可以与其他作者以前报道的涡环的行为形成对比。可以引入不同于涡环形成时间的特征时间尺度。该时间尺度（启动时间）指示偶极在其主要吸收来自喷嘴的射流而增长的初始时段之后开始平移的时刻。一个简单的模型，考虑膨胀和平移的竞争效应的开发，以获得估计的尺寸…
Evolution of a two-dimensional flow induced by a jet ejected from a nozzle of finite size is studied experimentally. Vortex dipole forms at the front of the developing flow while a trailing jet establishes behind the dipole. The dynamics of the flow is discussed on the basis of detailed measurements of vorticity and velocity fields which are obtained using particle image velocimetry. It is found that dipoles do not separate (pinch-off) from the trailing jet for values of the stroke ratio up to 15, which fact can be contrasted with the behavior of vortex rings reported previously by other authors. A characteristic time scale that is defined differently from the formation time of vortex rings can be introduced. This time scale (startup time) indicates the moment when the dipole starts translating after an initial period when it mainly grows absorbing the jet from the nozzle. A simple model that considers the competing effects of expansion and translation is developed to obtain an estimate of the dimensionle...