Non-deterministic CFD Simulations Of Wind Turbine Airfoil

The research on aerodynamic performance of the airfoil is important to the wind turbine design. Traditional numerical simulations on dynamic performance of wind turbine airfoil is deterministic CFD simulation. However, the design process and the complicated working environment of wind turbine would inevitably have lots of uncertainties which are not considered in deterministic CFD simulations. Therefore, the aerodynamic performance research of airfoil based non-deterministic CFD simulations has strong realistic meanings.This thesis mainly focuses on non-deterministic CFD simulation method and its application in the aerodynamic performance evaluation of wind turbine airfoil. Firstly, non-deterministic CFD simulation on a classic testing case, lid driven cavity flow are performed. Monte Carlo method is used to verify the accuracy and efficiency of non-instrusive polynomial chaos method and sparse collocation method. Computing results showed that the non-instrusive polynomial chaos method has a higher accuracy and better efficiency than the sparse collocation method.The validated non-instrusive polynomial chaos method was introduced into CFD simulations of a wind turbine airfoil.The airfoil surface roughness is assumed as a Gaussian distributed random variable The simulations results show that the lift coefficient is more sensitive to the random surface roughness than the drag coefficient. The pressure coefficient has big standard deviations at the leading edge and trailing edge of the airfoil of. A blunt trailing edge can effectively reduce the sensitivity at the trailing edge.Non-deterministic CFD simulations are also performed on the ice accretion process of a wind turbine airfoil. The flow velocity and angle of attack have random fluctuations. The research results show that, being compared with the clean airfoil, the aerodynamic performance of the iced airfoil drops quickly. And the incoming flow velocity is more influential on the aerodynamic performance than the attack angle.