| Project/Area Number |
13650202
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Fluid engineering
|
|---|
| Research Institution | Ariake National College of Technology |
|---|
Principal Investigator |
MINOTA Toyoko Ariake National College of Technology, Electronics and Information Engineering, Professor, 電子情報工学科, 教授 (70037852)
|
|---|
| Project Period (FY) |
2001 – 2003
|
| Project Status |
Completed (Fiscal Year 2003)
|
| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2003: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 2002: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 2001: ¥3,300,000 (Direct Cost: ¥3,300,000)
|
|---|
| Keywords | Laser-Induced Breakdown / Plasma Shape / Laser Focusing / ShockWave / Separation Bubble / Shear Layer / Shocklet / Laser Shadowgraph / シャドウグラフ / 正方形渦ループ / ステレオ・シャドウグラフ / 小渦列 / 方形渦ループの軸変更 / 正方形渦輪 / 剥離渦の発達 / 方形渦輪の軸変更 / 渦の相互作用 |
|---|
| Research Abstract |
The present studies are concerned with laser-induced breakdown phenomena, and with the interactions between a high-speed vortex ring and a small rigid body. The aims of these studies are to observe the shock waves and the plasma state formed by focusing a pulsed Nd-YAG laser (450 mJ/pulse) in atmosphere, and to prove the effect on the separation of the boundary layer and the flow field induced around a body caused by the shape of a body. The brief conclusion for the results of the experiments by shadowgraph technique are as follows.
1)A strong shock wave generated by focusing a laser propagates spherically around the plasma produced. Weak shock waves are generated inside the spherical shock wave, and catch up with the outer spherical shock wave.
2)The plasma state is made up of several layers of vortices shaped like a circular disc with the axis in the direction of the laser beam. The spaces between each layer are high pressure, and oblique shocklets go out from the edges of these discs. The plasma plume is emitted in the direction of the incident laser. The plasma occasionally goes into explosion which produces strong shock waves. The plasma is split in half, or a fragment of the breakup plasma comes apart the main and flies away. The outer spherical shock wave is influenced sharply by it.
3)As a circular vortex ring approaches a small body, a boundary layer is induced on the side face of the body. In a sharp edge body, an array of small vortices is formed between the edge of the body and the wall vortex core. In a blunt body, an inward-facing shocklet is formed near the separation point. The differences in these flow fields are caused by the velocity of the flow between the body and the vortex ring at the time that the separation bubble is induced.
|
