Final work : Structural modeling of propeller for multi-disciplinary design optimization

Abstract

Structural analysis for the propeller blade in a steady rectilinear flight operation is proposed to predict the blade stresses and ensure that the optimized blade can withstand the aerodynamic and centrifugal loads. The structural model is based on the Euler-Bernoulli beam theory for bending loads and the Saint-Venant theory for torsional loads in the blade. The proposed low-level structural model is more robust, fast, and efficient in terms of computational time and power than structural FEM simulations and can thus be easily integrated into a multi-disciplinary design optimization framework, including aerodynamics and aeroacoustics. The model is sensitive to changes in the blade's planform (chord, twist, and sweep) and airfoil geometry. In addition, to build confidence in the results the low-fidelity model was validated against high-fidelity structural (Fluid-Structure interaction) simulations of the propellers in both propulsive and regenerative regimes.

The sensitivity analysis was performed using various geometrical and operational parameters such as advance ratio, propeller pitch, and blade sweep. Expected outcomes from the sensitivity study were achieved, concluding that the centrifugal loads dominates over aerodynamic loads, and further consolidating the structural model and demonstrating that the low-level model performs satisfactorily in estimating the stress distribution. The proposed structural model serves as the foundation for aeroelastic analysis, which includes unsteady aerodynamic loadings, which were not considered in the current work.