Strut optimization analysis of azimuth thruster with contra-rotating propellers

Objective  This paper aims to investigate the effect of the strut geometry on the open water performance of the azimuth thruster with contra-rotating propellers （CRPs ）.

Methods  The RANS method and k-ω turbulence model are applied to predict the hydrodynamic performance of an azimuth thruster with CRPs and different strut design schemes at model scale and real scale in open water. Meanwhile, the flow field characteristics and wake fraction of the rear propeller are explored, and analysis on the flow separation at the stern of the strut after and before optimization is carried out.

Results  The results show that the optimization scheme of the struts moving forward and the leading edge thinning increases the propeller open water efficiency by 1.01%. The optimization scheme of the struts adopting a twist design and the strut section introducing cambers increases that value by 1.15%. In addition, the flow separation at the model scale is more serious than that at the real scale.

Conclusions  It is found that the optimized struts can reduce the flow separation at the stern, improve the rear propeller absorption of the wake vortex energy of the front propeller and increase the inflow of the rear propeller, which has practical engineering significance for improving the propulsion performance of an azimuth thruster with CRPs.