Abstract: Pipeline hydraulic conveyance of tube-contained raw-material is a new type of material transportation method which appears in modern logistics industry and has special advantages. In this paper, the distribution characteristics of fluctuation intensity of axial, vertical and lateral velocities of concentric annular slot spiral flow formed by double-piped carriages with different spacing-diameter ratios (S_D) are studied by means of model test. Results reveal that with the increase of S_D, the average value and range of fluctuation intensity of axial, vertical and lateral velocities remain basically stable, while the standard deviation and variation coefficient decrease. The characteristics of fluctuation intensity of vertical and lateral velocities are similar. Regardless of the S_D, the fluctuation intensities of vertical and lateral velocities are smaller than that of axial velocity by one order of magnitude, but the variation coefficient is about three times that of axial velocity. The reasonable spacing-diameter ratio of the double-piped carriages is 5-7. The research result is of referential value for the engineering application of tube-contained raw-material pipeline hydraulic conveyance.

Key words: pipeline hydraulic conveyance, annular spiral flow, velocity characteristics, fluctuation intensity, spacing-diameter ratio