1996 Fiscal Year Final Research Report Summary
Basic Consideration on the mixed flow with Water and Air
| Project/Area Number |
06452275
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
水工水理学
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| Research Institution | Toyo University |
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Principal Investigator |
OGIHARA Kunihiro Toyo University, Faculty of Engineering, Professor, 工学部, 教授 (60058071)
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| Co-Investigator(Kenkyū-buntansha) |
TANAKA Shuzou Toyo University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (40139043)
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| Project Period (FY) |
1994 – 1996
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| Keywords | Two phase flow / Similitude of Flow / Buoyed ratio / Flow in conduit / Flow in vertical shaft / 下水管縦シャフトの流れ |
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| Research Abstract |
The transportation of air by water flows in pipe line from the dam can be classified in two types by the process of motions as follows, the first in the motion of hydraulic jump and the second is the friction between water surface. There are many types of flow in long pipe line from the dam such as stratified flow, wavy flow and mixed flow are under the high water velocity and as plug flow and slug flow under the lower water velocity. So the first group is observed in upstream reach from the gate and the second group is in the downstream side where the water velocity becomes slower. There are three high air entrained conditions when the gate is opening from zero to 100% opening. The opening ratios of this condition are 0.25,0.6 and 0.8 in almost pipe diameter greater than 60mm diameter but it depends on the pipe lengh. The air entrained in the cases 0.25 and 0.8 opening is made by the motion of hydraulic jump and the case of 0.6 is by the friction of water surface. When the pipe diameter becomes smaller than 60mm, the case of 0.6 gate opening can not be observed, because the friction forces on the pipe wall becomes larger. This fact shows the air entrained flow is controlled by both the gravity force and friction force and the results by model test can not be applied to prototype directly except the consideration on the relations of these forces.
The air distribution in the channel of dam can be measured by the sensor used of the infrared rays. The structures in mixed conditions between air and water can be determined in large scale model but in the smaller scale model it is difficult to catch those structures. This fact shows the results from small scale model can not applied to prototype.
The theoretical model for the water and air mixed flow in vertical drop shaft can be made and the flow becomes different in the water velocity is greater than 6m/sec.
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Research Products
(8 results)
