Analysis Of Open Water Performance For High-skew Controllable Pitch Propeller

Traditional methods for predicting performances of propellers are lifting line method, lifting surface method and surface-panel method, which are all based on potential flow theory, and viscous effects are corrected according to experiments and experiences. These methods contain shortcomings that are difficult to overcome. First of all, potential flow theory ignores the influences of viscosity, which makes it impossible to correctly predict the flow of propeller current directly related to propeller noise, such as the formation of tip vortex, structure of trailing vortex and separation of flow, not to mention the scale effects caused by the large gap of Reynolds number between model propeller and true propeller; besides, potential flow theory needs to assume the shape of trailing vortex surface by experience, and this is quite sensitive to propeller parameters.In order to conquer these shortcomings of potential flow theory, in recent years, a large amount of scientific researchers have attempted to simulate the viscous flow surrounding propeller and its significant flow character by the method of CFD. Software FLUENT was designed based on the idea of "CFD software group", it can adopt appropriate numerical solution aiming at different flow, and acquire optimization of calculating speed, stability and precision. This thesis tends to simulate the 3D viscous flow of a high-skew controllable pitch propeller by using FLUENT, which can serve as a design method without collection of illustrative plates. The key problems planned to be solved are: modeling the propeller using fore treatment software GAMBIT, giving appropriate controlling zone, physics model and boundary conditions. This thesis mainly deals with two aspects as following:1) Model high-skew controllable pitch propeller, adopt appropriate computational mode (computational zone, grid division, boundary condition and solving parameters setting)to simulate the 3D viscous flow of propeller, obtain its open water performance, then compare the results with experiment data to prove the reliability of computational mode.2) Change the geometry of calculating zone and turbulence parameters respectively, calculate the hydrodynamic performance of propeller, and then compare the results.3) Select several different working conditions and calculate the open water performance of high-skew controllable pitch propeller under these conditions, which will make contributions to prediction of hydrodynamic performances of propeller.The comparison between calculated results and experiment data reveals that the numerical method adopted in this thesis can be used for simulation and prediction of open water performance for high-skew controllable pitch propeller, as well as obtain the flow pattern, velocity and pressure distribution which cannot achieve by using traditional methods. That will undoubtedly decrease the works of experiment and increase working efficiency.