| Project/Area Number |
18K18827
|
|---|
| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
|
| Allocation Type | Multi-year Fund |
|---|
| Review Section |
Medium-sized Section 19:Fluid engineering, thermal engineering, and related fields
|
|---|
| Research Institution | National Institute for Fusion Science |
|---|
Principal Investigator |
Takada Suguru 核融合科学研究所, ヘリカル研究部, 助教 (30578109)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
村上 正秀 筑波大学, システム情報系(名誉教授), 名誉教授 (40111588)
|
|---|
| Project Period (FY) |
2018-06-29 – 2021-03-31
|
| Project Status |
Completed (Fiscal Year 2020)
|
| Budget Amount *help |
¥6,240,000 (Direct Cost: ¥4,800,000、Indirect Cost: ¥1,440,000)
Fiscal Year 2019: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2018: ¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
|
|---|
| Keywords | 超流動ヘリウム / 可視化 / 狭小流路 / 準安定状態 / 沸騰 / PIV / 膜沸騰 / 間欠沸騰 / 過熱状態 / 超流動乱流 |
|---|
| Outline of Final Research Achievements |
The superheated state; meta stable state, easily is able to be created in narrow channel in saturated Superfluid helium (He II) though superfluid turbulence due to thermal counter flow must exist. In this study, particle image velocimetry (PIV) method was tried to be applied to superheated state collapse. The trial of PIV in narrow parallel channel were failed because of small S/N ratio. However, the several characteristics were revealed by PIV. During Boiling, velocity distribution was synchronized with the vapor oscillation but the DC flow that subtracted the oscillation motion still preserve same correlation in the case of no boiling state. On the other hand, high heat transfer coefficient appears when bubble repeats generation and collapse intermittently accompanying with metastable state of superheating. The vapor expands faster than that in the case of accompanying with normal He I. Rapid vapor expansion in the superheated He I caused the high heat transfer coefficient.
|
| Academic Significance and Societal Importance of the Research Achievements |
当初の計画通り過熱状態の崩壊を記述する物理を明らかにすることが出来ず過熱状態を自在に活用する方法を提案することは出来なかった。しかし、沸騰しても気泡の運動以外沸騰前と全く変わらない熱対向流の性質が明らかになるなど超流動ヘリウムの液相の乱流状態と沸騰開始には強い相関が見いだされない事が判り示唆されることは、特別なトリガーが存在するわけではなく幾何学形状に由来する熱流束の不均一などの比較的単純な物理でのみこの過熱状態の生成崩壊が決定されている可能性が高い。このような考察を延伸すれば超流動ヘリウムが冷媒として使用される超伝導加速空洞のような応用においての設計指針に適応できると考えられる。
|
