2000 Fiscal Year Final Research Report Summary
SEPARATION STRUCTURE OF BUBBLY FLOW AROUND A CIRCULAR CYLINDER WITH BUBBLE - BOUNDARY INTERACTION
| Project/Area Number |
11650165
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Fluid engineering
|
|---|
| Research Institution | THE UNIVERSITY OF TOKYO |
|---|
Principal Investigator |
ICHIKAWA Yasumasa GRADUATE SCHOOL OF ENGINEERING, RESEARCH ASSOCIATE, 大学院・工学系研究科, 助手 (40134473)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
MATSUMOTO Yoichiro GRADUATE SCHOOL OF ENGINEERING, UNIV.OF TOKYO, PROFESSOR, 大学院・工学系研究科, 教授 (60111473)
|
|---|
| Project Period (FY) |
1999 – 2000
|
| Keywords | BUBBLY FLOW / OUTER FLOW / CIRCULAR CYLINDER / SEPARATION / VOID FRACTION / DRAG COEFFICIENT / CRITICAL REYNOLDS NUMBER / VISUALIZATION |
|---|
| Research Abstract |
In the present research, the bubble behavior in the boundary layer along the cylinder surface is investigated experimentally. The bubble motion is observed by a high speed video from the inside of the cylinder through the transparent wall. The flow behavior in the boundary layer is visualized by an injected dye. In the present experimental conditions, the Reynolds number is corresponding to a sub-critical flow condition for single-phase flow and a super-critical one in the bubbly flow. The laminar separation is disturbed by the passing bubble, and the separation is attached on the surface. This causes that the separation point shifts backward and the form drag is reduced. The following results are also obtained from the photograph and the measurement of pressure distribution around the cylinder. The bubbles break up into small bubbles near the circular cylinder surface due to the strong shear stress in the boundary layer in the larger Reynolds number cases. The pressure distribution around the cylinder approaches to that of the super critical condition with the increase of void fraction.
|
