Numerical Study and Parameter Optimization of a Dual-jet Based Large Particle Collection System for Deep-sea Mining

A dual-jet collecting device is highly efficient at picking up small-sized polymetallic nodules; however, its performance is not as effective for large nodules in deep-sea mining. To address this problem, numerical simulations have been conducted to thoroughly investigate the flow characteristics and particle motions during the collection of larger nodules. The collection performance of the enhanced device is analyzed across varying front jet velocities (V-f), suction pressures (P-out), and nozzle heights (h/d). h/d ). The results reveal that increasing V-f improves the drag force and particle velocity in the jet impingement and upwelling zones, facilitating nodule lifting movement and transport. However, increasing P-out reduces the drag forces in these zones while increasing the particle velocity in the upwelling zone. A large P-out is not conducive to nodule initiation but has benefits for transport. Increasing h / d reduces the drag force in the anti-gravity direction in the jet impingement zone. The improved collecting device attains a pick-up efficiency that exceeds 80% for large-sized nodules when h / d < 1.3. The pick-up efficiency with suction pressure, which remains 40%, is higher than that without suction pressure when h / d > 1.3. The research findings may shed light on the design of more efficient dual-jet collection systems.