The Numerical Simulation Of The Flow Around The Rudder With NACA Airfoil Section And The Computer Aided Design Of The Semi-spade Rudder

The rudder is a very important control device of the ship. Because of its superior performance and simple structure, marine rudder has been used for a very long time. After the main scale and ship shape has been decided, the impact of the rudder on the ship's maneuvering has become of the most important factor. Modern ships require good maneuverability, so the design of the rudder is particularly important.At present, the design of the rudder is mainly based on good old-fashioned design of hull form design information. On the basis of the mother ship, designer needs to modify the rudder system and check the stability for many times, until user's needs are met and in accordance with design specifications. This process is cumbersome and complex; usually a small change will affect a lot of other changes, resulting in inefficient design, and the results always wrong. This has seriously affected the progress of ship design, and designers are exhausted. The work of rudder design is so boring. So how can we improve the efficiency of the rudder design, the fast and efficient design of utility rudder, has become an issue in front of the designer. This article is based on these ideas, the preparation of applications, implementation of mapping parameters, the computer automatically calculate and export the book of rudder design features to enhance the efficiency of the rudder design, simplify the design progress.The main job of this thesis has two parts: an application for automatically generating the graphics and the calculation of the rudder was wrote by VB; the flow around the rudder leaf was simulated by using FLUENT software, and the hydrodynamic characteristics of the rudder was calculated.There are a large variety of rudders with different functions. In this paper, the rudder with NACA symmetrical airfoil section was researched which has been used widely on the marine transport vessel. The seagoing ships share the biggest market.Because of the easy form and structure of rudder, it's possible to use parametric technology on rudder design. In this article, the chord length and aspect ratio of the rudder was extracted as a graphic rendering of the basic parameters. Users only need to enter the ship's main measure and the basic parameters of the equivalent rudder leaf into the window; the program can automatically drive AutoCAD drawings, and checking the size of the required strength. Procedures for the calculation send these dimensions into the calculation module. Some dimensions such as diameter of the rudder were selected by the user who decides which materials to choose. Finally the book of rudder design and calculation was generated automatically by the procedure. The whole process is very simple and quick, and the design was proved reliable and practical.There are two key steps in rudder design. A proper area of a rudder and its related parameters is needed to select in order to make sure the ship has a good stability; another choice is to calculate the hydrodynamic characteristics of the rudder. That is the pressure forces and torque acted on the rudder and the center of pressure. Then we can determine the size of components of the rudder, and select the proper steering gear.At present, there are two main methods of calculating the hydrodynamic characteristics of the rudder: One is the use of rudder data conversion model; the other is to use estimate approximate calculation formula. However, both methods have defects. Estimates using approximate formula are simple, but very imprecise. Model of information required to be carried out substantial testing, it's relatively precise but very expensive, and because there is still a lot of different between the rudder mode and the rudder, the errors still exist. This article is based on the FLUENT software, use the pre-processing software GAMBIT to model, use the S-A turbulence model to simulate the flow around the rudder, and calculate the hydrodynamic characteristics of the rudder. The RANS equation is directly solved by the finite volume method. Compared the calculation result with experimental data and actually nature, the result is reasonable and has some reference value to the research and design of the rudder. I have simulated the flow around a rudder with different attack angle. And by this software, it got some flow characteristics about the flow around a rudder with different angles and different Reynolds. I have studied the affect of the aspect ratio, flow rate, the rudder section on the hydrodynamic characteristics of the rudder. Based on the analysis of the parameters for the design, key parameters of the rudder were selected.