The flow visualization of the pulsating parallel jets issuing from two circular pipes was performed by the LIF method. As a result, it has been confirmed that the jet diffusion is promoted by adding the pulsation and this tendency is remarkable in the horizontal direction. Moreover, the jet diffusion was investigated by analyzing the velocity distribution obtained from the PIV. Making a comparison between the pulsating jet and the non-pulsating one, it has been clarified that the jet diffusion becomes large with the increase of the pulsating frequency. Furthermore, in order to study the effects of the pulsation on the structures of the jet, the wavelet multi-resolution analysis was conducted. It has been found that a large scale structure is broken into a small scale one, in adding the pulsation.

View full abstract

In the hydraulic conveying of the particles in the sedimentary bed of the two-dimensional duct, it was proposed by the authors that the high-efficient transportation can be achieved by installing the discharging plates from the particles surface above. In this paper, we examined the effects of interval and overall length of the discharging plates for the sediment removal on volumetric concentration and efficiency using the spherical glass beads. As a result, it was found that the optimum condition exists in a given condition. In other words, the volumetric concentration and the efficiency do not increase when the interval of the plates is too narrow. The additive total pressure drop increases and the efficiency lowers when the overall length of the plates is too long. The various particles behavior of different condition was clarified by the visualization images.

View full abstract