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Third Symposium on Turbulence and Shear Flow Phenomena
June, 25-27, 2003, International Center, Sendai, Japan

DOI: 10.1615/TSFP3

TURBULENCE MODIFICATION BY SOLID PARTICLES IN UPWARD GRID TURBULENCE OF WATER

pages 627-632
DOI: 10.1615/TSFP3.1060
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RÉSUMÉ

Turbulence modification by solid particles in grid turbulence of water is examined experimentally. Glass particles, 2450kg/m3 in density, are suspended in an upward turbulent flow behind a grid with M=12mm. Two particle diameters, dp=1.00mm and 1.25mm, are examined. The flow velocity is adjusted so that the particles stay quasi-stationary in the test section by the force balance between gravity and drag exerting on the particles. The resultant Reynolds numbers based on M and dp are respectively 1660 and 140 for dp= 1.00mm and 2000 and 210 for dp= 1.25mm. Kolmogorov length scales in single-phase flows are 0.43mm (ReM=1740) and 0.40mm (ReM=2000). PIV measurements of turbulence are carried out by using fluorescent tracer particles 26µm in diameter to avoid the effect of strong light scattering by the glass particles. It is found that the turbulence in the streamwise direction increases remarkably and selectively with C, the volumetric concentration of glass particles, in the range of C<0.50%. This increase is associated with the occurrence of columnar particle accumulation (CPA) into a region elongated in the streamwise direction. CPA alters significantly the longitudinal two-point velocity correlation, Ruu (Δχ), and vorticity correlation, Rw1w1 (Δχ), while it affects little the transverse two-point velocity correlation, Rvv (Δχ), where Δχ is the streamwise separation between the two points.

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