Computation of Hydrodynamic Load and Strength Assessment of Highly Skewed Propeller Available to Purchase

Ship Classification societies have rule requirements for assessment of propeller strength in terms of minimum blade thickness, however these rules generally covers only propellers of conventional geometry. In case of nonconventional (e.g. highly skewed) propellers, class societies ask for direct and detailed stress analysis for examination and approval. This paper introduces a procedure/strategy for assessing the strength of highly skewed propeller by determination of hydrodynamic load and consequent structural stress. The hydrodynamic analysis is performed separately using Reynolds Averaged Navier Stokes (RANS) solver STARCCM+ and structural analyses by finite element solver ANSYS. The hydrodynamic pressures as computed by CFD are transferred to the propeller model to calculate the resulting stationary stresses for maximum and minimum blade loading, using a quasi-static approach. The significance of root fillet in propeller design is demonstrated by comparing blade stress results with and without fillet at blade root. The stress concentration as a function of geometry and loading is also represented by the presented examples. The proposed method can assist the designer or reviewer to assess adequacy of strength of solid propellers as well as composite propellers of any geometrical configuration.