Experimental and Theoretical Analysis of Propeller Shaft Loads in Oblique Inflow

A series of model tests on an azimuth thruster model in oblique inflow conditions were performed for different heading angles and at different advance coefficients in pushing and pulling modes. Tests were performed in ventilating and nonventilating conditions. A novel shaft dynamometer was used to measure all six component forces and moments on the propeller shaft. It was found that the propeller shaft lateral force and bending moment were quite large, and thus, the load at the shaft-bearing positions was about three times larger than when only the propeller weight was considered. The results also showed that oblique inflow due to steering gives higher bending loads than when the propeller is subject to ventilation in the straight-ahead condition. A basic blade element momentum method (BEMT) was used to predict the forces and moments on the propeller shaft in oblique flow conditions. Fairly good agreement was found between the BEMT results and the experimental results.