Research On Basic Mechanical Properties Of Hybrid Wind Turbine Towers

Safety of wind turbine tower is important for supporting expensive wind power generation system.There are mainly cylindrical tower and lattice tower used widely in practical wind farms.The cylindrical tower is more common due to its small footprint,simple structure,conveniently construction.However,it is handicapped in mountainous areas because of complicated manufacture,transportation difficulties,a huge amount of foundation pit excavation,damage to soil and water,etc.Although the lattice tower has the advantages of manufacture,material consumption,cost,transportation,adjustment according to land surface,noise pollution caused by wind effect and tower foot limitation avoiding to the collision between tower and fan blade have a great impact on its application in a large fan.A hybrid wind turbine tower including upper cylindrical part and the lower lattice part was proposed and studied in this paper,to expand large-scale wind turbine farm to mountainous area.To validate the applicability of the tower system in mountainous areas,the basic mechanical properties of hybrid towers were studied in this paper by the numeraical simulation and theoretical analysis.The optimal range of aspect ratio and height ratio of hybrid towers were also investigated.Moreover,the mechanical behavior of the tower with unequal legs was analyzed.The main works are as following in details:(1)According to the basic design principles of the existing cylindrical,lattice and offshore wind turbine towers,design parameters of height,overhead width,bottom width,transition section width,web members and thickness of each segment were determined initially for hybrid wind turbine towers.At the same time,the simplifying mechanical models and load calculation formulas of hybrid wind turbine towers were proposed.(2)The finite element software ANSYS was used to establish 3d model of hybrid wind turbine towers,then comparison was carried out for hybrid wind turbine towers in order to select a suitable hybrid tower for generalizing.After that the static performance,dynamic performance,buckling performance and fatigue performance of hybrid towers with different aspect ratio,height ratio and types of unequal legs were analysed systematically.Basiced on the design and specification requirements,determining the optimal range of aspect ratio and height ratio of hybrid towers and the change rules of mechanical properties of hybrid towers with unequal legs.The design suggestions of hybrid towers were provided.(3)Comparing hybrid wind turbine towers and cylindrical wind turbine towers in some aspects of mechanical behavior,steel amount,transportation,production process,construction and maintenance,to define the advantages and disadvantages of the two tower forms,which provided some scientific and reasonable suggestions for the lectotype and design of wind turbine towers.