Composite Wind Turbine Blade

Wind energy research is being followed in the world as an alternative to fulfill increasing electricity power demand, United State Department of Energy is aiming to expand the wind power in the U.S. Currently, 15.4 GW of power are installed and operational, with an expected growth the U.S. wind capacity will be at 310 GW by 2030, representing 20% of the nation's power needs (Increasing Wind Energy's contribution to U.S. Electricity supply, 2008).

Research on composite wind turbine blade carried out in Embry-Riddle is described below:

FLUID-STRUCTURE INTERACTION AND MULTIDISCIPLINARY DESIGN ANALYSIS OPTIMIZATION OF COMPOSITE WIND TURBINE BLADE Mission:

To maximize aerodynamic efficiency and structural robustness while reducing blade mass and total cost.A multidisciplinary design analysis optimization (MDAO) process is defined for a composite wind turbine blade to optimize its aerodynamic and structural performance by developing a fluid-structural interaction (FSI) system. MDAO process is defined in conjunction with structural and aerodynamic performance of the blade which is divided into three steps and the design variables considered are related to the shape parameters, twist distributions, pitch angle, material and the relative thickness based on number of composite layers at different blade sections. Maximum allowable tip deformations, modal frequencies and allowable stresses are set as design constraints. Airfoil performance is predicted with 2D airfoils analysis, while 3D CFD analysis is performed by ANSYS CFX software. A parameterized finite element model of the blade created in ANSYS ACP composite prepost and used to define the composite layups of the blade. The results of the CFD and the structural analysis are used for the optimization process accompanied by the cost estimation to obtain a compromised solution between aerodynamic performance and structural robustness. For the MDAO process number of design of experiments (DOEs) is defined by G optimality method and a response surface is created. Sensitivity analysis is performed to observe the impact of input parameter on each output parameters for enhanced control of the MDAO process. Further, to improve aerodynamic performance of the blade, new design approach with modified Tip (winglet) and rotor section is studied and substantial improvement in power generated over high quality baseline wind turbine blade is presented.

A BASELINE STUDY AND CALIBRATION FOR MULTIDISCIPLINARY DESIGN OPTIMIZATION OF HYBRID COMPOSITE WIND TURBINE BLADE

Preliminary baseline finite element (FE) model calibrations and evaluations are developed to assist and guide multidisciplinary design optimization (MDO) of a large-scale hybrid composite wind turbine blade. The weight, displacement, and failure index are compared and used for calibration purposes. In addition, a cost estimation model is calibrated for labor hour, as well as labor cost, material cost and total cost. Stability of baseline wind turbine blade against harmonic resonance due to rotor rotation is validated by finite element analysis (FEA). A MDO process is proposed using the calibrated FE and cost estimation models. The MDO optimizes multiple objectives such as blade length, weight, manufacturing cost, and power production. For this analysis, the turbine blade is divided into regions and the sequence of hybrid laminate layup for each region is considered as design variables. Extreme wind condition for rotor rotation and rotor stop condition is considered as the applied load on the blade. The designed structural strength and stiffness are demonstrated to withstand the loads due to harmonic excitation from rotor rotation. A process of design procedure for obtaining an optimum hybrid composite laminate layup and an optimum blade length of a wind turbine blade structure is developed in this research.