A novel method of desynchronized operation of sails for ship wind-assisted propulsion system

The utilization of wind energy to provide assisted propulsion for ships is one of the current priorities for energysaving technology. Guided by the needs of engineering applications, traditional synchronized and desynchronized operations for wing sails are compared in the range of -90 to 90 degrees of angle of attack (AOA), and the wake structure, interaction and forces of the upstream and downstream sails are revealed by using a numerical method validated experimentally in Fluent. A desynchronized operating method is proposed that sacrifices the optimal AOA of the upstream sail to increase the propulsive efficiency of the overall system. Subsequently, a response surface model is developed to describe the relationship between the optimization objective thrust coefficient and the AOAs of the sails system based on the Kriging method. Then, the optimal operation is found for a starboard sail AOA of 22.6 deg and a port of 36.9 deg by using Particle swarm optimization, increasing the system thrust coefficient from 3.748 to 3.990, higher 6.5%. Finally, the desynchronized operation is shown to be effective in promoting the overall system's ability to provide thrust to the ship in different apparent wind directions.