| Project/Area Number |
62460096
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Fluid engineering
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| Research Institution | Waseda University |
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Principal Investigator |
YAMAMOTO Katsuhiro Waseda Univ., School of Sci. and Eng., Prof., 理工学部, 教授 (10063752)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHIOKA Eisuke Waseda Univ., School of Sci. and Eng., Prof., 理工学部, 教授 (50063699)
TAJIMA Kiyohiro Waseda Univ., School of Sci. and Eng., Prof., 理工学部, 教授 (60063335)
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| Project Period (FY) |
1987 – 1989
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| Project Status |
Completed (Fiscal Year 1989)
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| Budget Amount *help |
¥6,700,000 (Direct Cost: ¥6,700,000)
Fiscal Year 1989: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1988: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1987: ¥5,200,000 (Direct Cost: ¥5,200,000)
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| Keywords | High-Speed Water Jet / Jet Impact / Nozzle / Piston Impact / Unsteady Flow / Water Shock-Wave / Phase Change / Numerical Analysis of Compressible Flow / パルスジェット / 圧縮性流体の数値解析 / 気液二相流 / 衝撃波 / 噴流の衝撃力 / 非定常流の数値解析 / キャビテーション |
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| Research Abstract |
Pulsed water jets in the range of speed =200-500 m/s produced by piston impact are examined by numerical analysis and experiments. Taper nozzles and straight nozzles are used with outlet diameter 5 and 10 mm. In experiments the jet-head velocity and the impact pressure of the jets are measured and photographs are taken using Xe-flash and pulse ruby laser. In the numerical analysis finite difference method is employed for the flow analysis in the nozzles. The following conclusion can be made.
(1) 2 step Lax Wendroff method with FCT controlled artificial diffusion proves to be effective in the transient two phase flow analysis.
(2) After short transition the flow in the nozzles can be regarded as quasisteady. Vapor cavities are formed at the nozzle outlets during flow velocity decrease due to the piston deceleration. Especially in the straight nozzle outlets the contract flow and the separation with strong cavitation are formed. The vapor cavities also spread into the water column. The density and the velocity of flow change discontinuously at the interface of the two phase.
(3) On the assumption that the flow in the nozzles are steady maximum jet speed can be estimated. This estimation is enough applicable to the jets of the straight nozzles.
(4) The jet-head velocity of the straight nozzles increase as the jets travel but that of the taper nozzles decrease. Because the jet speed of the taper nozzles increase impulsively but that of the straight nozzles increase slowly.
(5) When the water jets are formed in the air severe collision and water disks around the jet axis are observed because of the change of the jet speed.
(6) The jet impact pressure at some standoff distance depend on not only the jet speed but also flow structure of the jets due to the nozzle shape.
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