Experimental study and parameter optimization of Coandă-effect-based collector of deep-sea polymetallic nodule

The design of polymetallic nodule collector demands high pick-up efficiency and compliance with stringent environmental standards. Hydraulic collection methods based on the Coand & abreve; effect are the mainstream approach, but their structural parameters require further optimization. In this study, an indoor tank experimental system was constructed, and the relationships between jet angle, suction velocity, jet velocity, motion speed, height above the bottom, and responses were analyzed using the Box-Behnken design method based on response surface methodology (RSM). A polynomial regression model was developed to link input parameters with key performance indicators. Nodule motion processes were precisely classified, and optimal structural parameter combinations were identified under the experimental conditions. The results indicate that jet velocity, jet angle, and height above the bottom had a significant impact on sediment disturbance. Nodule motion trajectories were categorized into four types: curvilinear ascent, rotational ascent, "L"-shaped ascent, and "S"-shaped ascent. Within the experimental range, the optimal parameter combination was determined to be a jet angle of 37.14 degrees, a suction velocity of 1.48 m<middle dot>s-1, a jet velocity of 8.5 m<middle dot>s-1, a motion speed of 0.55 m<middle dot>s-1, and a height above the bottom of 71.37 mm. These findings provide theoretical guidance for the design of polymetallic nodule collector.