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Volume 30, Issue 6
Displaying 1-7 of 7 articles from this issue
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Michihisa TSUTAHARA2002 Volume 30 Issue 6 Pages 321-329
Published: June 10, 2002
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSSimulation method for compressible flows by the lattice Boltzmann model is explained. Especially, the lattice BGK model with multi-speed particles for two-and three-dimensional flows is shown, and the relationship between the particles distribution function and the macroscopic quantities is described. The isotropic feature of the forth order tensor is shown to be necessary for the macroscopic governing equations. The Navier-Stokes equations of a compressible fluid are derivedfrom the lattice BGK equation. As a bench-mark test, the flow in a shock tube is performed, and the result agrees well with an analytical solution or that by the finite difference method. The aeolian tone emitted by a circular cylinder is also simulated, and a dipole emission of sound wave is detected synchronized with the Karman vortex street. The lattice BGK model for compressible fluids is shown to be one of powerful tool for simulation of gas flows.View full abstractDownload PDF (6175K) -
Makoto IMAI, Hiroto NAKAGAWA2002 Volume 30 Issue 6 Pages 330-335
Published: June 10, 2002
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSDownload PDF (3534K) -
Tomio IDA2002 Volume 30 Issue 6 Pages 336-348
Published: June 10, 2002
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSThe effect of difference between discharge flow angles from model runners and prototype ones on the actual Euler's head and the efficiency of hydraulic turbo-machines are discussed by using the scale effect formula used at present. Then discharge flow angles from the flat plate cascades similar to the runner vanes of models and prototypes are decided under consideration of boundary layer thickness which changes with Reynolds number and surface roughness. The discharge flow angle difference Δα between models and prototypes and the increase in efficiency en from the efficiency step-up formula are estimated as follows: Francis Turbine (NSQ= 62):Δα= 0.047°, Δη= 0.17% Francis Pump-turbine (NSQ= 33):Δα= 0.079°, Δη= 0.10% The same as above (pump op.):Δα= 0.079°, Δη=0 Kaplan Turbine (NSQ =109):Δα=0.017°, ΔΔ=0.27% where NSQ is the discharge specific speed.View full abstractDownload PDF (1478K) -
Part I: Velocity Fields at Rotor InletNorimasa SHIOMI, Kenji KANEKO, Wen-Xin Cai, Masakazu NISHIMURA, Toshia ...2002 Volume 30 Issue 6 Pages 349-356
Published: June 10, 2002
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSAn experimental investigation was carried out to clarify unsteady flow fields with rotating stall cell, especially structure and behavior of stall cell, in a high specific-speed diagonal flow fan. As its specific-speed is very high for a diagonal flow fan, its pressure-flow rate curve tends to indicate unstable characteristics caused by rotating stall similar to axial flow fan. Although for an axial flow fan many researchers have investigated such the flow field, for a diagonal flow fan few study has been done. In this study, velocity fields at rotor inlet in a diagonal flow fan were measured by use of a single slant hot-wire probe. These data were processed by use of the “Double Phase-Locked Averaging”(DPLA) technique, i. e. phases of both the rotor blade and the stall cell were taken into account. The structure and behaviors of stall cell at rotor inlet were clarified for three dimensional velocity components, Vm, Vθ, and Vn.View full abstractDownload PDF (7927K) -
Verification on Semi-Transverse Ventilation System with Disperse Exhaust Ports Using Model TunnelMakoto NOBUTA, Kuniaki FUKUSIMA, Eisaku MURATA, Kohzo KOMATSU2002 Volume 30 Issue 6 Pages 357-362
Published: June 10, 2002
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSThis paper represents the verification of Reference [31], in which we have introduced theoretical equations on the above ventilation system, and the diffusion of pollutants. The adequacy of equations were studied through the simulation, using the experiment apparatus of the model tunnel with model vehicles running. Test results indicated that the theoretical values of concentration distribution of contaminated air were very good match with the experimental values. Thus establishing the adequacy of the stated theoretical equation.View full abstractDownload PDF (706K) -
Jun ITO, Ken'ichi TOGASHI2002 Volume 30 Issue 6 Pages 363-373
Published: June 10, 2002
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSA theory of a three-dimensional cascade with partial cavitation in spanwise shear flow between two parallel plane walls is presented. An equation of motion with respect to disturbance pressure is transformed into two problems by separation of variables. One of them is that of spanwise direction and the other is that of sectional plane of a hydrofoil. For the problem of the spanwise direction, an existing analytical solution is adopted. The problem of sectional plane of the hydrofoil is reduced to a simultaneous integral equation with respect to singularity distributions and is solved by using the analytical method previously proposed by the author for the three-dimensional cascade without cavitation. These two kinds of solutions corresponding to individual eigenvalues are combined linearly, and expressions of cascade and cavity characteristics are obtained. Numerical calculations are carried out to clarify the characteristics.View full abstractDownload PDF (1116K) -
[in Japanese]2002 Volume 30 Issue 6 Pages 374-379
Published: June 10, 2002
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSDownload PDF (3052K)
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