Experimental and numerical study of a conceptual nodule pick-up device with spiral flow generator

Abstract

The nodule pick-up device is an indispensable component in deep-sea mining systems. To achieve high pick-up efficiency and low environmental disturbance during the collection process, a conceptual sucker-shaped nodule pick-up device is proposed by incorporating the spiral flow generator with four jet nozzles, featuring a jet start-spin mechanism. The performance, flow-field characteristics, and ambient disturbance were comprehensively examined under three swirling intensities through experiments and numerical simulations. The results showed that the device with tangential jet involvement can enhance the pick-up efficiency by approximately 12.8% in comparison with the suction-only mode. The augmentation in the swirling intensity leads to a transition in the nodule trajectory from a state of disarray to a well-defined circular motion owing to the disparate pressures encompassing the nodule. As the swirling intensity increases, the flow field with a vertical-axis vortex materializes into the vertical pressure disparity. Furthermore, the sea-bed deposits become more concentrated within the pick-up device (r/(D/2) < 0.5), withholding the tendency to disturb adjacent areas. These results will improve the understanding of the physics of nodule collection flows and help develop more efficient and environmentally friendly techniques for deep-sea mining.