| Project/Area Number |
63460091
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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 | Kyushu University |
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Principal Investigator |
INOUE Masahiro Kyushu University, Department of Engineering for Power, Professor, 工学部, 教授 (90037903)
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| Co-Investigator(Kenkyū-buntansha) |
FURUKAWA Masato Kyushu University, Department of Engineering for Power, Associate Professor, 工学部, 助教授 (30181449)
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| Project Period (FY) |
1988 – 1990
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| Project Status |
Completed (Fiscal Year 1990)
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| Budget Amount *help |
¥6,700,000 (Direct Cost: ¥6,700,000)
Fiscal Year 1990: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1989: ¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1988: ¥3,300,000 (Direct Cost: ¥3,300,000)
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| Keywords | Transonic Flow / Shock Wave / Boundary Layer / Unsteady Flow / Oscillation / Turbine Cascade / Experiment / Numerical Simulation / 衡撃波 / 二次流れ / 非定常 / タービン翼列 |
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| Research Abstract |
The shock wave oscillation due to shock-wave / boundary-layer interaction has been investigated experimentally for five linear transonic turbine cascades with different blade profile and / or aspect ratio. Displacement of the wake shock was measured by means of a schlieren optical equipment and a linear image sensor. The wake shock oscillation with inherent frequency was detected in a certain range of pressure ratio somewhat lower than the design condition in all the cascades tested. The inherent frequency, which ranges from 300Hz to 1100Hz for the five cascades, depends on the blade profile and the outlet Mach number. The displacement amplitude is less than 1 % of chord length. The aspect ratio has negligible effect on the inherent frequency. It is inferred from this fact that the cause of the oscillation can be explained by the two-dimensional consideration, but not by the three-dimensional one.
In order to verify the inference, the numerical simulation was carried out by means of a n
… More
ewly developed implicit upwind relaxation scheme for the Navier-Stokes equations of unsteady flow. The two-dimensional, Reynolds-averaged Navier-Stokes equations are discretized in space using a cell-centered finite volume formulation and in time using the Euler implicit method. The inviscid fluxes are evaluated using a highly accurate upwind scheme based on a TVD formulation with the Roe's approximate Riemann solver, and the viscous fluxes are determined in a central differencing manner. The algebraic turbulence model of Baldwin and Lomax is employed. To simplify grid generations, a zonal approach with a composite zonal grid system is implemented, in which periodic boundaries are treated as zonal boundaries. A new time-linearization of the inviscid fluxes evaluated by the Roe's approximate Riemann solver is presented in detail. No approximate factorization is introduced, and unfactored equations are solved by pointwise relaxation method. To obtain time-accurate solutions, 30 inner iterations are performed at each time step. The numerical results showed periodic unsteadiness overlapped with higher and lower frequency. The higher one is come from the Karman vortex shedding from a blade trailing edge, and the lower one corresponds to the experimentally detected oscillation with inherent frequency. Less
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