涡环

They found that the shift from a vortex-ring to a continuous-vortex gait depended on sufficient forward velocity to provide airflow over the wing during the upstroke similar to that during the downstroke.

他们发现，转移，从涡环一个连续涡步态依赖于足够的前进速度提供的气流，机翼在upstroke类似，在

Particles are tracked by computing the acceleration and motion equations of individual spherical particle within the computational domain in a Lagrangian way.

实验表明，圆湍射流切向不稳定性触发的蘑菇头状的二级流向涡将导致圆湍射流初级拟序涡环结构轴对称性质消失。

Vortex lattice method is presented for calculating the loading distributions on all blades of propeller and hub which a number of small hyperboloidal quadrilateral panels are discreted.

螺旋桨采用离散涡环法，将桨叶表面和桨毂表面离散为一系列双曲四边形，在四边形网格中布置集中涡环和线源分布，根据物面条件建立方程得到涡和源汇分布的强度。

The author established the axisymmetrical bubble with the vortex sheet and the vortex ring and established the three-dimension bubble with vortex ring respectively based on the achievements of the former researchers.

本文在总结前人研究成果的基础上，分别建立了轴对称涡面模型、涡环模型以及三维涡环模型。

The PIV measurement results show the properties and structures of the unsteady flow field in which a train of vortex ring s are formed at the sharp edge of the orifice, thus the energy and mass flux are .

通过对射流出口涡环的产生、发展及运动特性的分析，认识到涡环之间相互作用是形成&零质量&射流的流动机理。

In present paper a three-dimensional discrete vortex filament method is put forward to simulate the motion and bubble entrainment of an inviscid,incompressible vortex ring .

本文发展了三维离散涡模型用于模拟无粘不可压缩涡环的发展及其与气泡的相互作用，涡环被离散为平均分布在其中心线上的球形涡元，由Biot-Sarvart定律叠加每个涡元的诱导速度得到涡环的运动速度。

In vortex ring zone, streamwise vorticity and vortex ring wrap together and interact each other. This interaction leads to the breaking of vortex ring.

在涡环区，流向涡和涡环相互缠绕，相互作用，导致涡环的空间失稳及最终破碎，涡环的破碎标志射流开始转捩进入湍流阶段。

The numerical results were in good agreement with the measured results. The experimental and numerical results show that the vortex ring was induced by baroclinic effect and Helmholtz instability in the vicinity of the thruster exit after the donation wave exhausted the tube. The intensity, shape and location of the suspended shock varied when the shape of the vortex ring changed.

爆轰波溢出爆轰管后，斜压效应和Helmholtz不稳定导致涡环的产生，同时在流场中形成止于涡环的悬吊激波，涡环形状的变化又引起悬吊激波的强度、形状和位置的变化。

The analysis shows that with given grid size higher accurate difference scheme can give higher resolutions with wider range of scales, or with given accuracy large grid size can be used for the higher accurate difference scheme. The second part is the numerical simulation of two-dimensional axisymmetric jet. The simulation results show the structure in the near field and the initial transition. In the near field, Kelvin-Helmholtz instability leads to the formation of vortex ring, and nonlinear growth leads to the merging of vortex ring. This is the main instability form. Under the assumption of axisymmetry and two-dimensional computing conditions, the results are applicable only in the near field.

第二部分采用高精度的差分格式对二维轴对称射流进行了数值模拟，模拟结果显示了射流流场结构和涡结构的发展过程，在射流流场近区，K-H失稳导致涡环的产生以及非线性效应的增长导致涡环的对并是射流失稳的主要形式；分析指出在轴对称假设下的射流数值模拟只适用于射流近区的分析。

The model of 3-dimensional stretching vortex ring of turbulent elliptic jet in crossflow are discovered for the first time. It is pointed out that in the evolution of turbulent jet in crossflow the 3D vortex rings, which stretching, distorting, swing in transverse direction and twisting around the stream-wise, play the leading role in the large-scale coherent structures. The counter-rotating vortex pair observed in the literature is in fact the head of the 3-dimensional vortex ring.

首次发现和提出了湍流横向椭圆射流的三维拉伸涡环模型，指出在其大尺度拟序结构中真正占主导作用的是拉伸、扭曲、沿流向扭动、展向摆动和绕x轴的转动的三维涡环，在众多实验和文献中观察到的反向涡对其实是由三维涡环头部组成。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。