Research On Open Water Propulsion Performance Of POD Propeller

Pod propeller is getting people’s attention, gradually applied in various engineering fields of propulsion systems. Compared to traditional propeller, pod propeller has many advantages: Pod propeller adopts electric propulsion system which can avoid the mechanical way of power transferring in traditional; Saving cabins’space makes for cabins’arrangement and optimization; It can make stern lines design’s constraint reduced and increase ship efficiency; In addition, pod propeller has successfully integrated propulsion and manipulation, and can be manipulated to turn in any angle, greatly improving the flexibility of its manipulation. Pod propeller’s open water performance has an influence on speed and rotary maneuverability of ship, so it is necessary to study its hydrodynamic performance in depth.There are three kinds of pod propeller forms, this paper mainly study double-propeller pod propeller’s hydrodynamic performance. First we study on single propeller of pod propeller’s open water propulsion performance, based on CFD method to calculate the curve of open water performance for the single propeller, and compared with experimental results to verify the accuracy of CFD calculation method. We analyze pressure characteristics in microcosmic by pressure cloud picture, the result is consistent with the calculation in macroscopic. Further we calculate open water propulsion performance of propeller by five kinds of two-equation turbulence models of eddy viscosity model, and compare thrust, torque, and open water propulsive efficiency calculated by each turbulence model to get advantages and disadvantages of different turbulence models, SST k-co turbulence model is chosen as this paper’s calculation model.Second, the whole pod propeller’s hydrodynamic performance is calculated to get the curve of open water performance for the pod propeller. The pod propeller’s open water propulsion performance is compared with single propeller’s open water propulsion performance and that the pod propeller’s both thrust and torque get promoted compared to single propeller is found, while the pod propeller’s open water propulsive efficiency decline, indicating pod propeller’s torque improves faster than thrust. When the pod propeller is in rotation manipulation, it is in Off-design situation, and its hydrodynamic performance will change intensely. This paper studies pod propeller’s hydrodynamic performance in turning state. Its thrust coefficient, torque coefficient and open water propulsion efficiency are calculated when the pod propeller is rotated by10°,20°,30°,40°. The study found that the greater the pod propeller’s deflection angle, the greater the thrust and torque turn. When the pod propeller rotates in small angle, its open water propulsive efficiency gets small; while rotates in large angle, open water propulsion efficiency gradually rebound. And high speed can magnify changes of the hydrodynamic performance caused by the deflection.Finally, the pod propeller is optimized and designed from resistance and propulsion mainly, by reducing resistance and improving propulsion performance. The lines and size of POD propeller are improved.After computing and analyzing, open water propulsion efficiency of optimized POD propeller has been improved.