Stability Analysis Of Large-scale Wind Turbine Blade Under Severe Environment

Wind turbine blade is one of the most important components of the wind turbine. With windturbine becoming larger and larger, blade scale is also increasing. Large-scale wind turbines oftenoperate under complex and changed climates and environment, in which wind turbines alwaysencounter severe working conditions, such as gust, ice and snow, sand wind, storm and so on. Thecoupling effect of load changing and flexible structure may cause the blade deforming, the structurevibrating inevitably, or even lead to damage. These unstabilities of the blade disturb the normal work.Taking a certain type of1.65MW horizontal axis wind turbine blade as the research object, theCSD software ANSYS and the CFD software CFX are used to make fluid-solid coupling numericalsimulation of the blade under different environments. The major works are as followings:(1) The geometry shape and finite element model of the wind turbine blade is set up. On the basis ofthis model, numerical simulation of static test, modal analysis are undertaken compared with therelevant experimental data to verify the feasibility of the model of the blade structure.(2) A solving solution of fluid-solid coupling by CFX and ANSYS is put forward. The case of a thinelastic plane behind a fixed square rigid body vibrating in flowing fields verifies theeffectiveness of the proposed coupling method well. Based on this method, numerical simulationwith the constant wind situation is carried out.Compared with uncoupled conditons the resultsshow that the pressure difference between blade surfaces under the action of coupling increasefrom the spanwise direction. And coupled with the structure, vibration and deformation of bladeoccurs. The vibration modes meet the modal analysis results.(3) Stability analysis of the blade under gust wind and storm conditions is carried out. Mathematicalmodels of periodic extreme gust and random gust are established.Through ANSYS/CFX fluidsolid coupling the load and stability under the two gust and storm conditions are analysisedrespectively. The results shows that the blade deformation mainly occurs on flap-wise directionwith the first order and the displacement increases from the blade root to tip gradually. The stressmainly concentrated on the location of central spanwise direction. For stability and safetyconsideration, the structure should be appropriately improved.