Velocity Characteristics of Concentric Annular Slot Spiral Flow Around Rear Piped Carriage’s Body under Different Spacing

The traditional ways of transportation consume a large amount of fossil fuels, causing serious environmental pollution. As a special mode of transportation, tube-contained raw-material pipeline hydraulic transportation system has more advantages in the modern green logistics industry. In this paper, the velocity characteristics of the concentric annular spiral flow around the rear piped carriage’s body are analysed with the aid of the experimental investigation. This study analyses the distribution characteristics of axial velocity and tangential velocity of the flow when the spacing between two piped carriages changes. Besides, the root mean square (RMS) of the fluctuating velocity is used to quantitatively characterize the pulsation intensity, and the variation of the axial-velocity’s and tangential-velocity’s pulsation intensity under different spacing is investigated. Furthermore, some statistical parameters, including the mean, the range, the standard deviation and the variation coefficient, are investigated. Experimental results show that both the standard deviation and the variation coefficient of the axial or tangential velocity are highly correlated with the spacing. With the increase of the spacing, the aforementioned two parameters gradually decrease and then tend to be stable. The tangential velocity is 1~2 orders of magnitude smaller than the axial velocity, but the variation coefficient of the former is larger than that of the latter. The pulsation intensity of the axial velocity is about 1 order of magnitude larger than that of the tangential velocity. These research results could provide important reference value for the engineering applications of the tube-contained raw-material piped hydraulic transportation technology.

Key words: pipeline hydraulic transportation; concentric annular slot spiral flow; velocity characteristics; pulsation intensity; root mean square velocity