An investigation of load change of propeller in a four-propulsion vessel using CFD

In this paper, an attempt has been made to investigate the effects of propeller load changes against its performance in open water conditions. Load change of different propellers in a multi-propulsion vessel varies and there is scarce research in this area. The authors have made an endeavor to get a better understanding of the factors causing the load changes in a four-propulsion vessel. The load change of propeller has been linearly decomposed into three parts: ship hull influence, pure interference of other propeller, and coupled effect. A series of CFD simulations has been carried out to realize the decomposition of the load change of propeller. Simulations of single propeller in open water were used to obtain the basis for load change calculation. Simulations of self-propulsion with four propellers were used to obtain the total load change of propellers. To estimate the influence of ship hull, simulations of self-propulsion with only inner or outer propellers were carried out and the load change of propeller in this condition was evaluated. Simulations of four propellers in open water were used to determine the pure interference on one by the other three propellers. The existence of coupled effect appears as the sum of ship hull influence and pure interference does not equate to the total load change of self-propulsion with four propellers. The coupled effect arises, because the interference of other propellers is influenced by the wake. It is found that the influence of ship hull accounts for most significant amount of 75.38% for inner propeller and 45.38% for outer propeller. It has been determined that pure interference accounts for about 10% for both inner and outer propellers. The coupled effect accounts 15.36% for inner propellers and 45.8% for outer propellers.