Research on performance of cavitation jet equipment for deep-water cage cleaning

To study the cleaning mechanism and influence factors affecting of fouling organisms attached to cage net, we applied numerical simulation method and prototype testing to investigate the biofouling removal rate of cleaning equipment with different inlet pressures and nozzle diameters, and then explored the biofouling removal mechanism of aquaculture net cage under the action of cavitation jet. The numerical simulation results show that the maximum gas volume fraction of nozzle showed an increasing trend when the nozzle diameter was 0.6−1.0 mm under rated flow, and the maximum gas volume fraction value of d=1.0 mm nozzle was 37.5%. The flow velocity of the jet 40 mm away from the nozzle outlet decreased by 85.57%−96.98%, and the velocity of the nozzle decreased significantly in submerged environment. Further water tank cleaning test results show that when the input pressure was 18.8 MPa and the diameter value of nozzle was 0.8 mm, the largest cleaning rate of aquaculture nets of the cleaning equipment was 79.76%. The shellfish fouling organisms mainly fell off in the form of shell breaking under the impact of cavitation jet of cleaning equipment. After the cleaning, most of the residues was the soft foot silk tray of shellfish with strong adsorption. The soil on the surface of the net was completely removed and presented the primary color of the breeding net.