Study On The Characteristics Of Regional Atmospheric Boundary Layer Of Wind Turbine Based On OpenFOAM

Research on renewable energy has become an important issue in the field of energy applications.In general,wind energy is the most widely used type of renewable energy without considering large hydropower,so wind energy has made a considerable contribution to the world's overall energy supply and structural improvements.But the operation of wind turbines will definitely cause atmospheric energy loss,and the original normal energy cycle in the atmospheric boundary layer is disturbed.Therefore,it is necessary to deeply study the influence of wind turbines on regional atmospheric boundary layer characteristics.And provide support for optimizing the economic effects of wind farms.This thesis is based on the open source CFD platform OpenFOAM,combined with large eddy simulation and atmospheric boundary layer related theories,to study the effect of wind turbine operation on regional atmospheric boundary layer characteristics under different temperature stratification and different underlying surface types,and analyze the wind turbine wake vortex structure evolution.Study the effects of wind turbine wake on the characteristics of the regional atmospheric boundary layer under different temperature stratification and different underlying surface types by changing the temperature profile equation and the ground roughness.The results show that the influence range of wake under stable stratification is wider than that of wake under unstable stratification.The wind speed loss under the unstable layer is small.But in general,the effect of the temperature stratification on the wind speed is relatively limited.The difference in roughness has a different degree of influence on the development of the wind turbine wake region speed,and the speed recovery rate decreases as the roughness increases.The turbulent level of the atmospheric boundary layer has a great influence on the wake aerodynamics.The greater the disturbance caused by the atmospheric boundary layer,the faster the wake recovery.This disturbance can be caused by unstable temperature stratification or high surface roughness,which illustrates the importance of atmospheric boundary layer modeling for wind farm adjustment studies.At the same time,it is found that in the region above the hub height,the wake is greatly affected by the stratification state.In the region below the hub height,the wake is greatly affected by the roughness.The Q criterion is used to identify the wake vortex structure of the wind turbine,and the structural characteristics and evolution rules of the wake vortex structure are obtained.In the near wake region,the blade tip vortex has a stable spiral structure,presents regular advection characteristics,and forms a cylindrical shear layer along the wake boundary.At the beginning,there was almost no wake recovery and unstable flow.Subsequently,the vortex's diffusion rate gradually reached its maximum,causing a strong disturbance.At last,the atmospheric turbulence will rapidly decompose the wake structure,the pressure will gradually return to the ambient pressure,the shape of the cylindrical shear layer will no longer be stable,and the wake boundary will continue to expand in the radial direction.