Aeroelastic Modeling of Distributed Horizontal-Axis Wind Turbines

Wind turbines are highly aeroelastic systems because of the complex interactions between the aerodynamics, structural dynamics and control systems. Therefore, an aeroelastic model is the primary tool used to assess the performance, load characteristics, stability, and lifetime of a wind turbine. Aeroelastic models are required for every stage in the turbine life cycle. An aeroelastic model is essential during the design phase to iteratively evaluate the impact of design choices on turbine performance, lifetime, and various costs. It facilitates the wind turbine certification process and is also used to evaluate fatigue damage, quantify risk and the structural health of a turbine over the course of its life. This chapter describes aeroelastic modeling of wind turbines with specific focus on distributed wind turbines. The process of aeroelastic modeling of a distributed wind turbine is demonstrated using the National Renewable Energy Laboratory (NREL) 15 kW turbine. A brief introduction on the topic is provided in Section 8.1. Section 8.2 provides an overview of the tools used for aeroelastic modeling of wind turbines. The primary tool for aeroelastic modeling discussed in this chapter, called OpenFAST [1], is introduced in Section 8.2.1. The NREL 15 kW reference turbine is described in Section 8.3, and the process of aeroelastic modeling is demonstrated using the reference turbine in Section 8.4. Other helpful tools that facilitate aeroelastic modeling and post-processing workflow are discussed in Section 8.5.