Design Of Composite Marine Propeller

Metal materials, such as Nickel-Aluminum-Bronze, aluminum alloy, steel etc., aretraditionally the most common material for marine propellers. With composite materialsfinding increased usage in a wide variety of structural applications in the aerospace, civilconstruction, marine and offshore industries due to their excellent overall performances,composite materials e.g. FRP (Fiber Reinforced Plastics) has been applied in marine propellerconstruction in the past years. For marine propellers, the inherent material and mechanicalproperties of anisotropic composites can be both exploited to improve propeller performanceand gain energy saving by properly designing the ply stacking sequences, fiber orientationsand the geometry of propeller.While traditional metallic propellers are designed to be rigid and the deformation isusually ignorable under working conditions, the deformation of composite propellers is not soinsignificant and cannot ignorable as before any longer, which makes big differences betweendesign method for composite propellers and traditional metallic propellers. Therefore, the newdesign method is needed by considering both inherent material and mechanical properties ofcomposites for composite propellers. Much research work has been done on this topic and atwo-level (material and geometry) design methodology has been proposed.This paper provides new improvements base on the above method. The effects ofstacking sequence on the flexural behavior and stress distribution of composite propellerblades, as well as the effect on the hydrodynamic performance are evaluated. A compositepropeller is consequently designed and the matching of hull-engine-propeller is speciallyinvestigated.Firstly, the strength, deformation and vibration characteristic are numerically analyzed.In details, the flexural behavior of composite propeller, as well as the influences of differentstacking sequence on stress distribution and dry/wet frequencies of vibration are investigatedrespectively. Secondly, a coupled BEM/FEM approach is presented to study deformationcoupling effects on the hydro elastic behavior of composite marine propellers. The effects on hydrodynamic performance of stacking sequence is then discussed for composite propellerswith single ply orientation and multiple ply orientations respectively in steady, subcavitatingflow. Lastly, the shape of propeller is re-designed via pre-deformation approach. And thematching of hull-engine-propeller is investigated under both design condition and off-designconditions. The predicted performance and energy saving are compared to that of a rigidpropeller.Results show that with the less weight, a well-designed composite propeller performssimilarity as the rigid propeller at the design flow condition, meanwhile it does produce betterhydrodynamic performance than the rigid equivalent one at off-design flow conditions，whichleads to1%~2%improvement in energy efficiency.