| Situations such as shortage of traditional energy,serious environmental pollution and global climate change are becoming increasingly prominent.People cast their eyes at the ocean that accounts for more than 70% of the total surface area of the earth.At the same time,all countries are concerned about marine renewable energy.The most representative of the new marine energy conversion devices are wave energy and tidal energy.Throughout the application status of the world's marine energy technology,foreign countries started earlier,and technology matured,and formed a series of evaluation indicators,such as installed capacity,overall conversion efficiency and device operation stability.In view of the characteristics of the fluctuation and flow reciprocating of the tidal current,the energy capacity of the tidal current energy generation device is limited,while the marine energy technology in China is in a small-scale application stage,and there is a gap between the foreign power generation and foreign countries.Therefore,how to design a power generation device which can capture the reciprocating flow and achieve high efficiency has become the key research in this paper.To improve the efficiency of capacitation and bidirectional energy capture method,this paper uses direct drive structure type power generation device,and designs flow generating device based on bidirectional wave S impeller,and verifies the feasibility and effectiveness on the simulation experiment and flume experiment.Firstly,the paper summarizes the existing tidal power device characteristics,obtains turbine parameters,analyses bidirectional acquisition energy,puts forward the research route,introduces the airfoil theory,the basic theory of blade design and analysis of a large number of airfoil wing base,the ratio of resistance change with the attack angle and lift coefficient,drag coefficient and lift airfoil thickness with different series of airfoils and the same series different number of airfoil,and the numerical simulation verifies the change of surface pressure and speed on the different attack angle and thickness of airfoil,chooses five digit series airfoil as the basic research of the wing type.Based on the BEM theory,the formula is further studied to get the ultimate performance of the power factor,torque coefficient,lift coefficient and thrust coefficient related to the blade surface friction coefficient and the design tip speed ratio,provides references for the selection of impeller design parameters.The paper constructs the new S airfoil,and obtains the best attack angle and reasoning formula through the analysis of mechanical performance and hydrodynamic performance.Based on the traditional design method of the turbine blade,the optimized blade shape is calculated by Matlab software,and the impeller model is built in the UG software by coordinate transformation.This paper uses CFD method and fluent module,uses the passive sliding mesh model simulation of impeller based on UDF method,according to three-dimensional model,analyses its center of gravity and inertia of rotating impeller,compiles the UDF file;through simulating the hydrodynamic performance of the impeller under different conditions,sets the entrance velocity on the contrary,and obtains the surface pressure distribution,rotating domain pressure distribution and the tail velocity distribution,and verify the effect of two-way absorption capacity,flow around the tip and tail vortex.According to the actual experimental environment and conditions,the paper designs small scale model prototype,and makes detailed water flume experiment plan.Measures the important parameters and analyzes the experimental date to verify the overall stability of the turbine and the correctness of numerical simulation. |
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