Numerical Simulation Of Multi-factor Wind Field Characteristics In Typical Simplified Terrain

Wind energy plays an important role in the development of new energy.As a renewable clean energy,wind energy has been developed and utilized in an increasingly large range,which alleviates the excessive exploitation of fossil energy to a certain extent.The complex mountain wind field constructed by the actual wind farm is composed of several simplified mountain terrain wind fields.Therefore,the study of turbulent motion and turbulence characteristics of typical simplified terrain is conducive to accurately presenting the wind field distribution of actual terrain,which is of great significance to improve the power generation efficiency and wind energy utilization of wind turbines.At present,there are a lot of studies on typical simplified terrain and its wind field influencing conditions at home and abroad,but only the characteristics of symmetrical plane flow field are analyzed,and the coupling effect of wind field influencing conditions is rarely considered.Based on this,this paper adopts the numerical simulation method to systematically study the typical simplified terrain,and discusses the three-dimensional characteristics of the typical simplified terrain wind field and the comprehensive effect of the wind field influencing factors.In this paper,based on LES（large eddy simulation）,the wind field characteristics of typical simplified terrain are numerically simulated.Firstly,the three-dimensional flow field of a rough hill covered with vegetation canopy is simulated.The coherent turbulence structure,turbulent kinetic energy budget,spectrum and instantaneous flow field are studied,and the wind field characteristics and three-dimensional characteristics of the flow field are presented.Then,the flow field of a variety of simplified isolated three-dimensional hills is simulated,which is divided into two modules: rough hills and smooth hills.Based on physical quantities such as velocity,wind speed acceleration ratio and pulsation ratio,the effects of hill slope,topography and its coupling effect on wind field characteristics are systematically studied.The accuracy of the numerical model is verified by the wind profile of average velocity and fluctuating velocity.The final research results are as follows: the turbulence structure of three-dimensional hill includes transverse shedding,slope top shedding and canopy induced rotation;The spectrum reveals the energy concentration of turbulence pulsation at the wave crest,indicating the generation of complex coherent structures.Hill slope,terrain and its coupling effect significantly affect the magnitude and direction of average velocity and fluctuating velocity;Vegetation canopy will hinder the development of average velocity and fluctuating velocity at a certain height;With the increase of slope,the coherent turbulence structure of smooth hills will undergo an obvious evolution process,and after the introduction of ground roughness,the coherent turbulence structure will split into small vortices.