2007 Fiscal Year Final Research Report Summary
Analysis and prediction of cavitation phenomena in liquid metal
| Project/Area Number |
17560740
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Nuclear engineering
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| Research Institution | Ibaraki University |
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Principal Investigator |
TANAKA Nobuatsu Ibaraki University, Collage of Engineering, Professor (30323207)
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| Co-Investigator(Kenkyū-buntansha) |
FUTAKAWA Masatoshi Ibaraki University, JAEA, J-PARC center, Section chief (90354802)
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| Project Period (FY) |
2005 – 2007
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| Keywords | Cavitaion / Erosion / Pitting damage / Liquid metal / Numerical analysis / Experimental analysis / Liquid mercury / Spallation neutron source |
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| Research Abstract |
Following studies were investigated to analyze and predict cavitation phenomena in liquid metal.
As for numerical simulation we developed unified code of compressible and incompressible fluid flow numerically analyzing cavitation phenomena in liquid metal. We introduced a new cavitation model to the code, and verify the validation through some numerical benchmarks. In the first year, we studied the water cavitation in order to check our numerical model. As the results, we found that the effects of cavitation model and the equation of state are dominative in the numerical results. Then, in the next year, we studied the bubble growth and collapse process in mercury cavitation, we found that our numerical model well reproduces the behaviors of bubble of liquid mercury cavitation. In the simulation, we modified the equation of state to fit the state of liquid mercury and vapor mercury. In the final year, we investigated the mechanism of cavitation damage mitigation by flow field though nume
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rical simulation.
As for experimental studies, we chose a liquid mercury as liquid metals since a liquid mercury target system for the MW-class pulse spallation neutron source is being developed in the world. The behavior of mercury bubbles generated at the time when pulsed proton beam bombarded into the mercury target is considered by both the numerical analysis of bubble dynamics and the experiment using high speed camera It was found that the bubbles grows when the pressure overcomes the negative limit, and the growth depends on the holding time of negative pressure and unloading time. We also made clear that we can observe the bubble behaviors by monitoring acoustic oscillation since the bubble collapsing behaviors are experimentally confirmed to be agreed well with the harmonic oscillation caused by bubble collapse. The speed of mercury microjet generated at the time when a bubble is collapsed by the positive pressure was observed to be 200 m/s at the boundary walls. The shock wave caused by the bubble collapse generated the secondary cavitation.
Through these numerical and experimental studies, we made clear of the mechanism of cavitation generation in liquid metal and can propose the methods to avoid the generation of cavitation and to mitigate the pitting damage by cavitation. Less
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Research Products
(13 results)
