| As the environmental pollution and climate destruction caused by fossil fuels utilization is increasingly severe,as well as the resource exhaustion,it becomes an urgent matter to seek for a clean and renewable energy for the society.Among those substitutions,exploiting ocean energy has aroused great attention for its enormous potential in many coastal countries.Among all the factors,the key point determining the performance of a generator unit is the design of horizontal water turbine in which ocean wave and current energy can be absorbed and transformed.When ocean current is acting on the blades in both vertical and horizontal directions,the turbine,whose shaft is connected to a direct drive generator,rotates and thus the electricity is produced.However,due to the development of the horizontal axis turbine is in the initial stage,there are many problems such as efficiency is not high and it is difficult to calculate the power generation characteristics of the horizontal axis water turbine with the equation before the experiment.This thesis study of the power generation of the horizontal axis water turbine based on CFD method and simulation method,the method of improving the efficiency which is based on the optimization of airfoils and add shroud is proposed,and the method of simulate the generation characteristics of horizontal axis water turbine is proposed.The following is the research ideas of this thesis:(1)This thesis optimize the airfoil,First,the numerical simulation analyse horizontal axis water turbine with basic airfoil,reference the wind blade optimization method,then according structure optimize theory propose the optimize method—cut part of the blade,get the airfoil optimize column,combine with basic airfoil parameter,establish model and set up the boundary and basin in Gambit,export the mesh and import it in Fluent,give the initial conditions then starting calculate,through compare the output result by optimized airfoil,obtain the best airfoil,compare the hydrodynamic characteristics between the best airfoil and basic airfoil,obtain the liftdrft force and power gain efficiency.(2)The method that is install the shroud around the horizontal axis water turbine is adopted,first modeling and meshing the shroud,water turbine and the combined body between Shroud and water turbine.Then have the simulation research on major parameters of shroud on Fluent.Obtained the major parameters results,in the length: the hydrodynamic performance is better when expanding the length,on the basis of overall coordination,determine the length of 1500mm;In angular: when analyse it from10°~30°,we determine the angular is 26°.Comparing the efficiency of horizontal axis water turbine when the shroud exist or not,the conclusion is that add shroud can improve the horizontal axis water turbine efficiency,and quantify the results;also do the experiment with shroud,the experimental results verify the accuracy of the simulation results.(3)The Matlab/Simulink simulation method is proposed to study the generation of the horizontal axis turbine.In the first place,the torque value of the ocean energy acting on the basic airfoil is calculated by the fluid simulation.Then a model of electric generator system is built up in Matlab/Simulink,and torque data is got by simulation calculation,which can drive electric generator to produce electricity,the current will handle by rectifier and filter,then display by the scope.The simulation results are in good match with the results of experiment has been completed,it can establish the turbine power system model in Simulink to simulate,better solved the problem that is difficult get power generation characteristics of horizontal axis water turbine with the equation.This thesis deep study with the horizontal axis turbine,obtained the optimal airfoil and shroud parameters that can improve the efficiency,and give out the scheme that solve the power characteristics,has laid a good foundation for research of the power generation of the horizontal axis turbine. |
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