Research on the Characteristics of Flow Velocity in a Two-way Annular Flume Available to Purchase

Annular flume has been widely applied in researches of the laws of sediment motion for its favorable features: it meets the distance requirement of fine sediment settlement without the influence of inflow and outflow; meanwhile, it has such advantages as simple structure and easy operation. In this study, propeller current meter is used to measure the layering current velocity of an annular flume under different water depths and rotating speeds, by which we can obtain the characteristics of the flow field. There exists nonnegligible secondary flow in the annular flume, and its maximal reduction can be achieved by rotating the channel and the top ring in contrary directions. In this experiment, a proper selection of the speeds of the channel and the ring is provided. Based on the analysis of experimental data, it can be seen that the vertical velocity distribution of the annular flume follows the S-shape distribution law. The flow rate has a larger velocity gradient only at boundaries, while in the central area of the flow field, the velocity gradient remains small and the curve fits a cubic function. The radial distribution of velocity is linear and the velocity decreases from the outer edge to the inner edge, which leads to the same distribution of each cross section. So the two-way annular flume can be used to simulate an infinite long straight flume.