Study On Dynamics Of Rotor System In Vertical-axis Tidal Turbine

As the requirement of energy is getting bigger and bigger, the output of fossil fuel can’t meet the demands of the development of the world’s economy. So developing some new kinds of energy is becoming an important task in the field of energy. Ocean current generation is a new kind of potential resource which has the characteristics of safety, environmental protection, widely distributed and renewable. Tidal turbine is the main equipment of ocean current generation. The function of tidal turbine is to provide power for generation. Tidal turbine works in the ocean which condition is very complex. There is not only an unbalanced force, its own gravity and centrifugal force, but also a non-steady hydrodynamic and ocean storm surge. And there are several serious problems, such as seawater corrosion and biological contamination. Under this complex circumstance, in order to ensure the safe operation, the requirement of strength of tidal turbine is quite high.This paper makes a study on the hydrodynamic characteristics and the flexural vibration characteristics of constant arm length vertical-axis tidal turbine and variable arm length vertical-axis tidal turbine, and offers reference for actual ocean current generation experiment. The main contents and conclusions are as follows:1. Improve the method of stream-tube which is the forecast of flow excitation. Simulate the characteristic of constant arm length turbine and variable arm length turbine and get the result of equal-area criterion and equal-perimeter criterion variable arm length turbine. It turns out that the Project3of equal-area criterion has the maximum average torque compared with the constant arm length turbine. This provide a model of flow excitation for the turbine rotor system dynamic characteristics.2. Build a dynamic model of the turbine rotor system through the method of finite element and calculate the critical speed of rotation and unbalance response of the turbine rotor system using my program with the method of Newmark. Provide a model of dynamic response which is under a complex flow excitation. It turns out that the one time frequency is the main response of unbalance response. The shaft centerline orbit is ellipse. Compared with the business software, the error of my program is under3%.3. Deduce the bending vibration differential equation of variable structure axisymmetric body-variable arm length turbine and calculate the bending vibration response of constant arm length turbine and variable arm length under the affection of fluid. It turns out that the additional moment of inertia has a great effect on critical speed. With the increase of additional moment of inertia, the critical speed decrease, especially for the third order critical speed; The variation of the arm length has some effect on bending vibration response, and make a different performance on the direction of X and Y; There is complex vibration despite the arm length and is mainly as1-6frequency multiplication.4. Made a comprehensive performance testing system of vertical-axis turbine and made a test of hydrodynamics and vibration. The result of this experiment shows that the constant arm length is mainly as frequency multiplication and the simulation accords with the experiment result one qualitatively.