# Performance Prediction of Composite Marine Propeller in Non-Cavitating and Cavitating Flow
## 1 Introduction  
Composite marine propellers have many advantages over existing metal propellers, such as improved propulsion efficiency, light weight, excellent corrosion performance, and low vibration and noise induced by cavitation. They were applied to leisure vessels such as yachts in the 1990s and equipped on naval vessels requiring low underwater radiated noise, including submarines, in the Netherlands, Germany, and United Kingdom in the early 2000s [1]. However, there is little information available about these propellers because they are a technical development for military purposes. [PERSON] et al. carried out model tests of rigid and flexible composite propellers at the Naval Surface Warfare Center, Carderock Division 36-inch water tunnel [2]. They discovered that the propeller efficiency and cavitation performance of the flexible propeller were superior to those of the rigid propeller. [PERSON] et al. presented a coupled boundary element method (GEM)-finite element method (FEM) approach to study the fluid-structure interaction of flexible composite propellers in subcavitating and cavitating flows [3]. They also determined that the bending-twistingcoupling effects of anisotropic composites and the load-dependent self-adaptation behavior of composite blades are the primary sources for the performance improvement of composite propellers [4; 5]. In addition, Airborne Composite of the Netherlands manufactured composite propellers for their naval vessels, and Howaldtswerke-Deutsche Werft, a German shipbuilding company, confirmed the effects of weight and noise reduction by manufacturing composite propellers for submarines [6]. [PERSON] et al. manufactured composite propellers using compression molding process, and their hydrodynamic performances and radiation noise were measured [7; 8]. [PERSON] et al. developed a new design procedure for a flexible propeller under steady conditions, using a coupled vortex lattice method (VLM)-FEM, and analyzed a simply supported flexible plate under a uniformly distributed load [9; 10]. Recently, the application of composite propellers has been extended to commercial vessels that require high fuel efficiency and lighter shafts. Nakashima Propeller in Japan succeeded in commercializing the world's first composite propeller with a diameter of 2 m in 2014 after seven years of research. At present, the Nakashima propeller has a track record of applying composite propellers to more than five medium and small vessels such as tankers and ferries in Japan. Excellent performance was reported from full-scale trials, such as a 6% improvement in fuel consumption and a 40% reduction in engine room vibration. In addition, Nakashima Propeller obtained the approval for a composite propeller with a diameter of over 4 m from ClassNK in 2016 and plans to develop a composite propeller for a 60 k DWT bulk carrier with a diameter of approximately 7 m [11]. Hyundai Heavy Industries has derived a conceptual design and manufacturing method for composite propellers through a feasibility study of a composite marine propeller. BEM and computational fluid dynamics (CFD)-based hydroelastic analysis methods have also been proposed to derive a preliminary design for composite propellers. In addition, further opportunities to improve the propulsion performance during off-design operating conditions were identified by adapting the composite material to the marine propeller [12; 13; 14]. [PERSON] et al. developed lifting surface theory (LST)-FEM coupling method to predict the hydroelastic performance of a flexible composite propeller in a non-uniform wake and examined the influence of the lamination direction on the deformation of the flexible composite propeller [15]. In addition, a design methodology of the specific flexible composite propeller was suggested [16]. The hydrodynamic benefits of applying composite propellers have already been discussed through many studies as above. The advantages of composite propellers mentioned above can be divided into two categories.