Structure Design And Hydroelastic Optimization Of High Performance Composite Propeller

Propeller noise is a major source of ship-radiated noise. With the increasingly urgent acoustic stealth requirements, propeller plays an important role in the vibration and noise reduction of the ships. In recent years, composite propeller, as a new type of propulsion, is key for achieving the low-vibration and low-noise ship. The structure characteristics and the operating principle of the composite propeller are quite different from that of the traditional metal propeller, so the structural design and the analysis method of the composite propeller are the research focus and difficulties in the present. In this paper, two coupled numerical simulation methods are presented, by analyzing the working characteristics and mechanical behaviors and combining with propeller theory, computational fluid dynamics methods and finite element method of composite structures, for the composite propeller in uniform and non-uniform flow, respectively. The structural design and the hydroelastic optimization of composite propeller is completed. The details are as follows:The structural characteristics and the operating principle of the composite propeller are analyzed, the difference of the structural design and analysis is revealed between composite propeller and metal propeller, the importance of the fluid-structure interaction is shown for the composite propeller.Combining the computational fluid dynamics method based on the viscous flow theory with the finite element method of composite structures, the three-dimensional steady equation and hydroelastic equation of the fluid-structure interaction are established, which provide a theoretical basis for the numerical simulation of the fluid-stucture interaction of the composite propeller.A numerical simulation method of the steady fluid-structure interaction is presented for the composite propeller in uniform flow. The convergence calculation is completed using different mesh sizes and this method is verified. Various performances of the five-bladed and seven-bladed composite propellers are analyzed and evaluated, including the open-water performance, steady hydrodynamic pressure, stiffness, strength. The effect of the fluid-structure interaction on different type propellers is studied. The importance of the fluid-structure interaction is exhibited for composite propeller. By comparing with the performance of the metal propeller, the difference of the performance of two material types propellers is revealed. The shape reconstruction of the composite propeller is achieved by using the pre-deformated strategy and the results of the steady fluid-structure interaction.The wet mode calculated method of the acoustic fluid-solid interaction is presented based on the finite element method. The dry and wet modes performances of composite blade are analyzed and compared with that of metal blade. The influence of the added mass is exhibited. The relationship between the material properties and the wet mode performance is revealed. According to the finite element method based on the modal strain energy, a numerical calculated method of the structural damping of composite blade is presented. The results of the numerical calculated is compared with those of the experimental modal analysis, this method is verified. The structural damping of composite blades with different laminated paramters is computed and evaluated. The design ability of structural damping is exhibited for composite propeller. By completing the damped structural dynamic analysis of composite blades with different laminated paramters, the method of evaluating the dynamic performances of composite propeller, using the structural damping design, is established.A numerical simulation method of the transient fluid-structure interaction is presented for the composite propeller in non-uniform flow. The convergence calculation is completed using different mesh sizes and different time steps, and this method is verified. The hydroelastic performances of the five-bladed and seven-bladed composite propellers are analyzed and evaluated in the design condition, including the unsteady hydrodynamic load, unsteady hydrodynamic pressure, deformation, dynamic stress, hub loads. The difference of the hydroelastic performance between composite blade and metal blade is exhibited. The hydroelastic performance of the composite propeller with different stacking sequences is discussed. The hydroelastic optimization of composite propeller is achieved.A counter-rotating propeller is preparation. The three-dimensional surface test, the weight test and noise test of composite propeller are completed. The results of the composite propeller are compared with those of the metal propeller, the advantage of the composite propeller is exhibited.