Numerical analysis on bending-torsional coupling stiffness characteristics of composite propeller

  Objectives  The bending-torsional coupling deformation degree of a composite propeller reflects the stiffness characteristics of the blade, which in turn have a certain correlation with its hydrodynamic performance. A fiber layer design for a composite propeller is optimized from the perspective of stiffness.

  Methods  Taking a DTMB 4383 composite propeller as the research object, based on the self-iterative algorithm of the fluid-structure interaction of the composite propeller, a numerical calculation method for the bending stiffness and torsional stiffness of the blade is constructed. The stiffness of the blade under different ply schemes is numerically calculated under the conditions of unidirectional carbon fiber cloth or orthogonal carbon fiber cloth laid on the blade, and the bending-torsional stiffness characteristics of the blade and its corresponding laws with hydrodynamic performance are studied.

  Results  The numerical calculation results show that the thrust coefficient of the single blade, the difference value of the thrust coefficient of the composite propeller, and the stiffness of the blade exhibit relatively synchronous change laws; under the same elastic modulus in the main direction, the minimum difference value of the thrust coefficient of the composite propeller with orthogonal carbon fiber cloth is greater than that with unidirectional carbon fiber cloth; when the elastic modulus of the material decreases, the stiffness of the blade decreases, and the thrust coefficient of the single blade and the difference value of the thrust coefficient of the composite propeller also decreases; when the stiffness of the blade is small, the composite propeller can give fuller play to the advantages of the adaptive flow field, and the bending-torsional coupling produces larger pitch deformation, resulting in a smaller periodic thrust ripple than that of a metal propeller in the high and low flow areas.

  Conclusions  The results of this paper can guide the optimization design of composite propellers by improving the hydrodynamic performance of the stern.