State of the art in the aeroelasticity of wind turbine blades: Aeroelastic modelling

Abstract

With the continuous increasing size and flexibility of large wind turbine blades, aeroelasticity has been becoming a significant subject for wind turbine blade design. There have been some examples of commercially developed wind turbines experiencing aeroelastic instability problems in the last decade, which spokes for the necessity of aeroelastic modelling of wind turbine blades.This paper presents the state-of-the-art aeroelastic modelling of wind turbine blades, provides a comprehensive review on the available models for aerodynamic, structural and cross-sectional analysis, discusses the advantages and disadvantages of these models, and outlines the current implementations in this field. This paper is written for both researchers new to this research field by summarising underlying theory whilst presenting a comprehensive review on the latest studies, and experts in this research field by providing a comprehensive list of relevant references in which the details of modelling approaches can be obtained.

Design and Experimental Investigation of Airfoil for Extruded Blades

“…The aerodynamic characteristics of the designed airfoil are obtained for the Re numbers of 8x10 4 , 2x10 5 and 3x10 5 . During testing, some low amplitude vibrations starts to creep in at higher AoA of more than ±30°.…”

“…Following are the airfoil geometry parameters that has major influence on the aerodynamic properties Camber : Though the widely used airfoils for vertical axis wind turbines are symmetrical ,cambered airfoils do have their presence especially in smaller turbines .The cambered airfoil aid in self-starting the turbine due to wider drag bucket and thus it address a the major drawback of Darrieus type turbines especially in low Re numbers in the range of 8x10 4~2 x10 5 .The cambered airfoil produces high lift in low Re and the performance reduces significantly in higher Re above 3x10 5 [2] .Hence the goal of the current study is to design a symmetrical airfoil .…”

“…Genetic Algorithm (GA) has been successfully applied in myriad aeronautical shape optimization in the past [5]. A robust algorithm and less computational efforts are the key factors to optimize the target pressure distribution based on the imposed constraints.…”

“…The conventional airfoils such as NACA 4 series family have required thickness, but thickness distribution is not sufficient to incorporate a rectangular spar web. Hence the study is dedicated to design an airfoil for use in vertical axis small wind turbines in the Reynold's number (Re) range of 8x10 4 to 4x10 5 .…”

“…The airfoil profile was generated by prescribing the target pressure distribution obtained from the seed airfoil (NACA 0018) optimized by employing Genetic Algorithm (GA) by imposing constraints on minimum thickness, thickness distribution, lift and drag coefficient. The designed airfoil was validated experimentally through wind tunnel tests at Reynolds number 8x10 4 , 2x10 5 and 3x10 5 .…”