| The tidal current energy of our country can account for about 14% of the world.The beam of the Zhoushan archipelago in the Zhejiang,the tidal of average flow rate is up to 2 ~ 3 m/s.And the sea is smooth, easy to develop at the protection of the use of islands in the sea area. The key technology of developing and utilizing tidal current energy is the acquisition of the kinetic energy of the tidal current. The most commonly equipment is hydraulic turbine. The hydrological data shows that the average sediment concentration in Zhoushan sea is about 0.187~0.551g/L. When the water flow through the turbine,the particles are affected by turbine rotation. It is inevitable that the turbine rotation react to the turbulent fluctuations. Especially in the case of high flow rate and high speed,near wake region and wake flow area is in turbulent state.The rotation of the particles will aggravate the pulsation of the flow field, and form many eddies.It is the source of energy consumption. The loss of energy causes the output power of the turbine and the hydraulic efficiency drops.In this paper, the flow around a circular cylinder and a square cylinder at a subcritical Reynolds number are studied and explored for effects on hydrodynamic characteristics of sediment_laden flow on the structure of water.The subject of low sediment concentration is suspended sediment. By studying the force of the circular cylinder and square cylinder to explore the action mechanism of the suspended sediment on the flow viscosity coefficient.Through the analysis of cylinder wake vortex shedding pattern and flow field analysis to explore the influence of suspended matter on the turbulence diffusion,at the same time the reliability of CFD method is verified by model test.Secondly, the methods of design about hydraulic turbine are refered and Turbine Blade Parameters are calculated.The dynamic characteristics of the airfoil are analyzed by Profili.The high lift drag ratio of NA63A614 are choosed to determine the angle of attack of each foliosine. the installation angle and chord is reoptimized 3D coordinates are introduced into 3D modeling software Solid Works, which is obtained by MATLAB calculation.In sediment_laden flow, the mechanism of flow around a circular cylinder and a square cylinder is preliminary understood. The horizontal axis tidal turbine performance in sediment_laden flow is explored. Based on the two-dimensional flow research,according to CFD on the Tidal Turbine were analyzed in the water and muddy water performance.By focusing on the analysis of water and sediment flow in turbine static pressure, streamline, blade tip vortex, kinetic energy and hydrodynamic parameters,firstly revealed the characteristic of hydraulic turbine flow at low sediment concentration.The sand affects the static pressure of the flow field when it entered the flow field especially the blade surface and near wake region.The sand rotating influenced turbulent kinetic energy and destroy the shape of the tip vortex. The particles have a significant effect on the hydrodynamic parameters of the turbine.If the sediment concentration is high, the fluid viscosity will increase and the axial force of thrust will enlarge.The sediment concentration is higher, the particle rotation and collision is more intense and the pressure energy is consumpted, the output power of turbine is low.The turbine power in a 8% sea sediment falls by up to 20% than no sand sea. The effect of low sediment concentration on the velocity lies in the far wake region. |
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