1998 Fiscal Year Final Research Report Summary
Investigation on Suppression Mechanism of Rotating Cavitation in Inducers
| Project/Area Number |
09555060
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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 | 展開研究 |
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| Research Field |
Fluid engineering
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| Research Institution | Tohoku University |
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Principal Investigator |
KAMIJO Kenjiro Tohoku University, Institute of Fluid Science, Professor, 流体科学研究所, 教授 (90282003)
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| Co-Investigator(Kenkyū-buntansha) |
NAGASHIMA Toshio Tokyo University, Department of Aeronautics and Astronautics, Professor, 工学系研究科, 教授 (70114593)
YAMADA Hitoshi National Aerospace Laboratory, Kakuda Research Center, Head, ロケット推進研究部・流体機器研究室, 室長
ISHIMOTO Jun Tohoku University, Institute of Fluid Science, Assistant, 流体科学研究所, 助手 (10282005)
OIKE Mamoru Tohoku University, Institute of Fluid Science, Associate Professor, 流体科学研究所, 助教授 (70292282)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Turbopump / Inducer / Cavitation / Rotating cavitation / Cryogenic / Two-phase flow / Cavitation surge / Suppression |
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| Research Abstract |
Rotating cavitation and cavitation surge occurred in a liquid oxygen pump inducer of the LE-7 engine and in a fluid system including the pump, respectively, Both the phenomena were almost completely suppressed by a simple modification of the inducer upstream housing. However, the mechanism of the suppression could not be fully explained. In this study suppression mechanism of the rotating cavitation and the common characteristics between rotating cavitation and cavitation surge were investigated.
First, an experiment was performed using three inducer housings including a modified one and an inducer which had almost similar dimensions of the LE-7 pump inducer to obtain a map of modes of unsteady cavitating flows. It was clarified that the modified inducer housing shifted the region in which the rotating cavitation occurred to higher flow rates.
Second, another experiment was conducted using a high speed filming and a particle image velocimeter(PIV) to observe the flow upstream of the inducer. It was clarified that the modified inducer housing increased back flow near the tip of the inducer inlet and that the back flow increased the cavity volume, which resulted in the increase of cavitation compliance. The increase of cavitation compliance is also considered to be a main cause of suppressing the rotating cavitation.
Third, it was also clarified that rotating cavitation and cavitation surge was a very similar phenomena from both the experimental and theoretical analyses. Furthermore, fairly high frequency of the cavitation surge could be explained by taking into consideration the phase delay of the mass flow gain factor which is a major cause of both the rotating cavitation and cavitation surge.
Fourth, it was confirmed that an analysis of a cryogenic two-phase flow which includes the effect of cavitating bubbles could be applied to the unsteady internal flow of an inducer.
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