Direct Numerical Simulation of Dynamic-Rotational Controlled Jet
Direct Numerical Simulation of Dynamic-Rotational Controlled Jet
复制标题
动态旋转控制射流的直接数值模拟
DOI：
10.1007/978-3-319-30602-5_9
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Toshitake Ando
中科院分区：
文献类型：
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作者：
Koichi Tsujimoto;Toma Onodera;Toshihiko Shakouchi;Toshitake Ando
为了发展一种新的混合方法，我们对动态控制自由射流进行了直接数值模拟。作为动态控制，假设射流来流速度沿流向交替旋转。为实现高精度计算，空间离散采用正弦或余弦级数与六阶紧致格式的混合格式。从瞬时涡结构的角度，发现流型随旋转频率的变化而发生显著变化，随着频率的增加，螺旋模和纠缠模依次出现。从射流宽度和卷吸量等系综平均流动特性可以证实，射流在垂直于旋转轴方向上广泛传播，由于动力控制，上游射流的混合显著增强。此外，为了量化动态控制的混合效率，作为另一混合度量，检查统计熵。与无控制射流相比，混合效率得到了显著提高，表明动态控制对改善混合性能具有重要意义。
In order to develop a new mixing procedure, we conduct DNS (direct numerical simulation) of dynamic controlled free jets. As the dynamic control, it is assumed that the inflow velocity of jet is alternately rotated around streamwise direction. To realize the high accurate computation, the discretization in space is performed with hybrid scheme in which sine or cosine series and 6th order compact scheme are used. From view of instantaneous vortex structures, it is found that the flow pattern considerably changes according to the rotating frequency, i.e., according to the increasing frequency, helical and entangled mode appear in turn. From the ensemble averaged flow properties such as jet width and entrainment, it is confirmed that the jet widely spreads perpendicular to the rotating axis and that the mixing of upstream jet is markedly enhanced due to the dynamic control. Further in order to quantify the mixing efficiency of the dynamic control, as another mixing measure, a statistical entropy is examined. Compared to the uncontrolled jet, it is confirmed that the mixing efficiency is markedly improved, suggesting that the dynamic control can be expected to be useful for the improvement of mixing performance.