Three-dimensional CFD Numerical Simulation Of A Vertical Axis Wind Turbine With Semicircular Blades

As a renewable clean energy,wind energy has great potential for development.The research of wind energy utilization is developing vigorously,and all kinds of new wind turbine theories and characteristics provide theoretical support for improving the utilization rate of wind energy.At present,the wind turbines can be divided into two main types:horizontal and vertical axis wind turbines.These two kinds of wind turbines are widely used in their respective characteristics.Taking the vertical axis wind turbine as the research object,the aerodynamic performance of the three blade,four leaf,five leaf and six blades was analyzed by the computational fluid dynamics software(CFD),the sliding grid technology,the SIMPLE algorithm and the three-dimensional model.The variation characteristics of the output power of several wind turbines under the wind speed of 8m/s were simulated,and the turbulence kinetic energy distribution around the blade and the blades around the blade were also analyzed.Surface pressure distribution and velocity distribution near blade.At the same time,the flow and solid coupling method is used to consider the response of several wind turbines under the same wind speed,so as to provide technical support for improving the design of wind turbine.The main contents of this paper are as follows:1.the vertical wind turbine power changes with the five blade blade width.The results show that the power of the wind turbine rises first and then decreases with the increase of blade width.For the wind turbine with the diameter of 4 meters,the maximum power of the wind turbine is at the blade width of 0.8m and the blade speed of 17 rpm,at this time the power value is 212.47 W,and the wind energy utilization coefficient is 15.61%.2.study the distribution of turbulent kinetic energy near vertical wind turbine blades of five blade.The turbulence kinetic energy near the blade shows that the turbulent kinetic energy changes obviously when the wind field passes through the blade,and the turbulent kinetic energy is larger in the windward side of the blade.While the turbulent kinetic energy of the leeward is smaller and the blade width is 0.8m,the turbulence energy near the blade is smaller.At this time the wind field has smaller disturbance to the blade and the power loss of the wind turbine is the smallest.3.study the five blade near the vertical wind turbine blade air flow velocity distribution.From the air flow velocity image near the blade,it can be seen that the velocity of the air flow is larger in the front of the blade,and the velocity difference is formed in the center part of the five leaf blade,thus forming a velocity difference.With the increase of blade width,the air flow velocity near the blade is increasing gradually.When the blade width reaches 0.86 m,the width of the blade is too large.The rate of air coming is easy to bypass the fan blades,while the fan blades do less work.The width of the blades is higher than that of the 0.82 M,and the utilization rate of the time and space air is higher.4.the vertical distribution of wind turbine blade near five blade static pressure.From the distribution of static pressure near the blade surface,we can see that the pressure on the left side of the blade is larger than that on the leeward side,while the pressure on the lee side is relatively small.At the same time,it can be seen that the pressure of the central area of the wind turbine is low,and the negative pressure zone appears to reduce the blade deformation caused by the over pressure of the blade surface,and the blade thickness can be increased in the outer part of the blade.5.the characteristics of wind turbine under three or four and five or six blades were compared.For four wind turbines with different blade numbers,the equivalent pressure on the surface of the four leaf and six blade wind turbines is obviously higher than that of the five leaves and the three blades under the same ambient wind environment.The highest equivalent pressure of six leaves is 3.121 MPa.The blade surface stress and blade shape variables of the six blade wind turbine are larger.When the fan blade is selected,we should avoid the use of the six blade wind turbine as far as possible.6.by comparing the 2D and 3D simulation results,the rationality of the three-dimensional model and its rule is analyzed.