Mean flow properties and turbulent characteristics of open channel flow with bed-load transport were experimentally studied in the 550×25.8×20cm flume with erodible gravel bed. The sand with the diameters of 0.59mm and 1.19mm were used and the rate of bed-load transport reach to 13g/cm·sec. The velocity were measured by ADV, and the characteristics of the turbulent intensity and the spectra of turbulent velocity were analyzed. The experimental results show that: 1) the mean velocity profile of open channel flow with bed-load can be expressed by a log-law; 2) the turbulent intensity near bed decreases with the increase of bed-load transport rate; 3) the spectrum of turbulent velocity also changes as the increase in bed-load transport.

抄録全体を表示

The turbulence structure of the liquid-solid jet flows impinging on a flat plate has been experimentally investigated with Particle Image Velocimetry (PIV) system and Laser Doppler Anemometer (LDA). The diameter of the particles, d=1.05mm, is nearly ten times as large as the Kolmogorov length scale in the free jet region apart from the plate. It has been confirmed that the turbulent intensity in the carrier fluid has been enhanced due to the effect of the largescale particles. The increase of power spectra has been clearly found in the high wavenumber range. The turbulence modification due to the large particles still remains in near-wall regions.

抄録全体を表示

Measurements of three dimensional velocities of solid-liquid upflow in a vertical pipe were made by using an acoustic doppler velocimeter (ADV). The neutral plastic particles with the density of 1. 047kg/cm³ and the diameters of 1. 4mm, 0. 66mm and 0. 33mm were transported in a vertical pipe of 19cm inner diameter. The concentration of particles in the flow ranged from about 0. 055% to 1. 564%. It was found that the turbulence intensity of fluid increases with the increase of concentration and diameter of particles and lager than that of clear water flow at the same flow condition; while at the case of particle diameter 0. 33mm and concentration 0. 385%, the turbulence intensity decreases than that of a clear water flow at the same conditions.

抄録全体を表示

A turbulence structure has been experimentally investigated in the particle-laden vertical jet flows impinging on a horizontal flat plate. The diameter of the particles is nearly ten times as large as the Kolmogorov length scale. In experiments, the volumetric concentration c of the dispersed phase was set at 0.08% and 0.13%. In addition, the distance H between the nozzle outlet and the impinging wall was widely varied, thereby varying H/D from 10 to 30, where D is the nozzle diameter. The characteristic flow patterns and turbulent quantities were measured with a Laser Doppler Anemometer (LDA). As a result, it has been confirmed that the turbulent intensity in the carrier fluid has been enhanced due to the existence of the large-scale particles. In the wavenumber space, the power spectra have been clearly enhanced mainly in the high wavenumber range, which corresponds to the particle length scale.

抄録全体を表示