Numerical research on the effect of brackets installation angle on the propeller wake field and propulsion performance in a four-screw ship

A series of full-scale self-propulsion simulations of a four-screw ship with different bracket installation angles using the Reynolds-averaged Navier–Stokes (RANS) method were conducted. The effects of the bracket installation angle on the propeller wake field and propulsion performance were investigated and studied. The result shows that the nominal wake low-speed region generated by the shedding vortex moved inward with the bracket angle increased. When the bracket angle turns inward 3°, the effect of shedding vortex almost disappeared in the outer propeller disc. The outer propeller shows a significant increase in thrust and torque, and the time-average load difference between inner and outer propeller drops to below 5%. The research conducted in this paper fills a gap in the study of full-scale four-screw ship appendages. The design method for determining the bracket installation angle by inflow direction is of practical significance to the design of four-screw ships. •The wake field and propeller performance in a four-screw ship with different bracket installation angles is studied.•Full-scale simulations are conducted to avoid scale effect.•Two sets of comparisons are focused: the inner and outer propeller, and the comparison of different bracket angles.•The inner bracket angle should be greater than that of the outer bracket to achieve the better inner propeller efficiency.