Experimental study on the influence of pre-swirl stator on the fluid field of ship sterns

Abstract

To explore the flow mechanism of a ship's fluid field and the working principles of energy-saving appendages, this study uses the scale model of a bulk carrier as its research object and conducts a fluid field measurement experiment by using the large underwater stereo particle image velocimetry system of Harbin Engineering University. First, three-directional fluid measurement tests are conducted on the fluid field with and without a pre-swirl stator to establish the flow structure around the pre-swirl stator. Second, by comparing the axial velocity distribution, tangential velocity distribution, and vortex distribution of the ship's fluid field with or without pre-swirl stator and by extracting the axial velocity at different radii, this study elaborates the influence of the pre-swirl stator on the fluid field and its energy-saving mechanism. Results show that the pre-swirl stator can produce a pre-rotating flow in front of the propeller in the opposite direction of the propeller rotation. Moreover, the lower and middle blades of the pre-swirl stator exert great influence on the distribution of the fluid field, thereby resulting in the displacement of the peak angle, an increase of the peak value, and an increase of the inlet velocity of the fluid on the propeller plane. These effects can improve fluid conditions and propulsion performance.