Abstract

The results of numerical simulation of the formation and motion of turbulent vortex clouds (puffs) resulting from the blowing of pulsed jets with various initial velocities and durations are given. A model of axisymmetric turbulent flow described by the time-dependent Reynolds equations is adopted. It is shown that, regardless of the initial conditions, a puff which has the shape similar to a sphere develops after the same dimensionless time interval from the instant of jet outflow. In the rest of the space the vortex-induced flow is close to a potential flow. It is found that in the vortices the velocity profiles in the axial and transverse directions are close to self-similar profiles and similar each other for various conditions of outflow of pulsed jets. The time dependences of the geometric and kinematic characteristics of puffs, namely, the location of the cloud center (points with the maximum velocity) and the radius of a sphere equivalent in volume to the puff, as well as the maximum and mean velocities, are given and analyzed. For the jet outflow conditions considered, the characteristics of puffs turn out to be similar.

中文翻译：

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湍流涡云（烟团）形成和运动的数值模拟

摘要

给出了由于不同初始速度和持续时间的脉冲射流的喷射而产生的湍流涡旋云（喷流）的形成和运动的数值模拟结果。采用含时雷诺方程描述的轴对称湍流模型。结果表明，无论初始条件如何，从射流流出瞬间起经过相同的无量纲时间间隔后，就会形成类似于球体形状的烟团。在其余空间中，涡流引起的流动接近势流。研究发现，在脉冲射流的各种流出条件下，涡流中轴向和横向的速度分布接近于自相似分布并且彼此相似。烟团的几何和运动学特性，即云中心的位置（具有最大速度的点）和与烟团体积相当的球体的半径，以及最大和平均速度，为给出并分析。对于所考虑的射流流出条件，抽吸的特征是相似的。