Research on the interactions between compressible vortex rings and the properties of generated shocklets

可压缩涡环相互作用及产生激波特性研究

• 批准号: 08650230
• 负责人: MINOTA Toyoko
• 金额: $ 1.34万
• 依托单位: Ariake National College of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08650230/
• 关键词: compressible vortex ring; turbulent vortex ring; transition of vortex ring; shocklet; shock; vortex interaction; optical shadowgraph; shock focusing

The present study is concerned with the compressibility effects appearing in the motion of an unsteady flow that is initially subsonic. A fundamental flow, used in experiments, is the flow following behind the shock wave emitted from the open end of a shock-tube. This flow has a vortex ring at the head of the unsteady flow discharged continuously out of a shock-tube.First, the dynamic motions of a fundamental flow were studied by means of an optical shadowgraph method. Next, the phenomena appearing in more complex flows, produced by the interactions of a fundamental flow with other variables, were studied by the same method. The following results are discussed briefly below.The core of a head vortex ring includes a inner core with strongly concentrated vorticity and a vortex sheet surrounding it. These two sections become turbulent-like independently, during the process of the transition from a lamminar to a turbulent vortex ring. Afrer rearward-facing shocklets are generated within the head vortex ring, a very thin vortex ring appears in front of the head vortex ring. The thin vortex ring reverses its position to the rear of the head vortex ring reverses its position to the rear of the head vortex ring. The unsteady flow behind the head vortex ring, is excited by a weak shock wave, which results in the production of small vortex rings. These small vortex rings subsequently interact with each other, and then these small vortex rings merge with the adjacent ones.Supersonic zones develop within more complex flows, and shocklets are generated. The point of focus, at which the pressure increases dramatically, is produced as a result of these interactions between the shocklets and the small vortex ring.These results indicate that the unsteady flow following behind a head vortex ring makes significant works for the compressibility effects appearing in the present flow fields.

本研究涉及最初为亚音速的非定常流运动中出现的压缩性效应。实验中使用的基本流动是跟随从激波管开口端发出的激波的流动。该流在从激波管中连续排出的非定常流的头部有一个涡环。首先，采用光学阴影图方法研究了基本流的动态运动。接下来，通过相同的方法研究了由基本流与其他变量相互作用产生的更复杂流中出现的现象。下面简要讨论以下结果。头部涡环的核心包括涡度强烈集中的内核和围绕它的涡片。在从层流涡环过渡到湍流涡环的过程中，这两个部分独立地变得类似湍流。在头部涡环内产生向后冲击波之后，在头部涡环的前面出现非常薄的涡环。薄涡流环将其位置反转至头部的后部 涡流环将其位置反转至头部的后部 涡流环将其位置反转至头部的后部。头部涡环后面的非定常流动被微弱的冲击波激发，从而产生小涡环。这些小涡环随后相互相互作用，然后这些小涡环与相邻的涡环合并。超音速区域在更复杂的流动中发展，并产生冲击波。由于冲击小波和小涡环之间的相互作用，产生了压力急剧增加的焦点。这些结果表明，头部涡环后面的非定常流动对出现的压缩性效应起了重要作用。在现在的流场中。