1992 Fiscal Year Final Research Report Summary
Fluctuation Distribution and Vortex Structure of in Three Dimensional Separated Flow
| Project/Area Number |
03650049
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Aerospace engineering
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| Research Institution | CHIBA-UNIVERSITY |
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Principal Investigator |
NISHIKAWA Nobuhide Professor of Faculty of Engineering Chiba University, 工学部, 教授 (80009753)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Three Dimensional Separation / Boundary Layer / Lateral Vortex / Visualization / Turbulent Unsteady Flow / Visualization |
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| Research Abstract |
The followings seem to be rarely emphasized in the existing studies for the separation phenomena around axisymmetric body.
1. Some results clarify that the two-dimensional type separation appears away from the start of 3-D open separation. Firstly, the separation lines by oil flow pattern show small deviation from the edges of the plateau of measured pressure distribution. Secondly ,the skin friction lines at windward side intersect not tangentially but normally to the primary separation line S_1.
2. The power spectra of the velocity as C.T.A measurement data show the peak frequency of 19 Hz for Re=27000,alpha=40ﾟ. The frequency can be attributable to vortex shedding in two- dimensional mode such as 15 Hz of theoretical shedding frequency for circular cylinder.
3. The velocity and frequency of disturbance is large at rheta =135ﾟ at aft body where the positive flow or reversal alternatively appears. The swing of the lateral vortex exhbits the mode of 1 Hz or so at alpha>30ﾟ,while it is fixed on the model surface at alpha<30ﾟ,Re=8000.
4. In the narrow region between the primary and secondary separation line the strong axial flow reversal appears,which consist with the upper part of the elongated and clock wise vortical pattern between S_1 and S_2.
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