On Study Of An Optimal Method For Hydrodynamic Performance Of A New Type Of Vertical-axis Turbine

A hydrodynamic optimal method to enhance the energy conversion coefficient of the vertical-axis variable-pitch turbine is presented in this paper based on the analysis of the existing mathematical models ,on the computational methods for predicting the hydrodynamic performance of turbines and on the available experimental results. By applying mathematical optimal theory, a mathematical model for optimizing the hydrodynamic attack angle of the blades of turbines is formulated and some numerical results are obtained as well. Much attention is focused on the comparison and studying of the reliability of the different methods when applied to this kind of turbine and focused on the probing into the hydrodynamic mechanism of the new optimized turbine. All of these is the important base of the selecting of turbines, the designing of hydrodynamics performance, and the general designing of marine currents power plant.At first an analysis of the basic principles of the vertical-axis variable-pitch turbine is given including two methods to calculate the induced velocity. One is the three different streamtube-methods which are single-disk single-streamtube (SDST), double-disk single-streamtube (DDST) and multi-streamtube (MTT) method based on the momentum theory, the other is the vortex method (VTTH) based on the potential eddy theory.Then as a typical example some results drawn by using the introduced methods of the vertical-axis cycloid turbine are given and compared with the experimental data. The purpose is focus on the validation of the introduced methods what are the foundations of the hydrodynamic performance calculation and the optimal method.At last with the prototype of the vertical-axis cycloid turbine, the optimal method and its mathematical model based on conjugate gradient method are presented in order to enhance the energy conversion coefficient. Such optimal results as the energy conversion and the relation between attack angle and azimuth angle are given with particular analysis to sum up the reason of the improved performance of the turbine.