Uncoupled and Twist-Bend Coupled Carbon-Glass Blades for the LIST Turbine

Wetzel, Kyle; Locke, James

doi:10.2514/6.2004-170

Cited by 5 publications

(4 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Results of these efforts showed a reduction in fatigue damage with respect to a baseline model without BTC coupling but also designed for a different maximum tip deflection. Studies on small blades of similar size are also reported by Locke and Valencia, Wetzel and Locke and Lin and Lai. …”

Section: Introductionmentioning

confidence: 99%

Optimization‐based study of bend–twist coupled rotor blades for passive and integrated passive/active load alleviation

et al. 2012

View full text Add to dashboard Cite

This work is concerned with the design of wind turbine blades with bend-twist-to-feather coupling that self-react to wind fluctuations by reducing the angle of attack, thereby inducing a load mitigation effect. This behavior is obtained here by exploiting the orthotropic properties of composite materials by rotating the fibers away from the pitch axis.The first part of this study investigates the possible configurations for achieving bend-twist coupling. At first, fully coupled blades are designed by rotating the fibers for the whole blade span, and a best compromise solution is found to limit weight increase by rotations both in the spar caps and in the skin. Next, partially coupled blades are designed where fibers are rotated only on the outboard part of the blade, this way achieving good load mitigation capabilities together with weight savings. All blades are designed with a multilevel constrained optimization procedure, on the basis of combined cross-sectional, multibody aero-servo-elastic and three-dimensional finite element models.Finally, the best configuration of the passive coupled blade is combined with an active individual pitch controller. The synergistic use of passive and active load mitigation technologies is shown to allow for significant load reductions while limiting the increase in actuator duty cycle, thanks to the opposite effects on this performance metric of the passive and active control solutions. ABBREVIATIONSADC actuator duty cycle AEP annual energy production BTC bend-twist coupling CAD computer-aided design DEL damage equivalent load DLC design load case EOG extreme operative gust FEM finite element method HAWT horizontal axis wind turbine IPC individual pitch control LQR linear quadratic regulator PID proportional integral derivative SQP sequential quadratic programming

show abstract

Section: Introductionmentioning

confidence: 99%

Optimization‐based study of bend–twist coupled rotor blades for passive and integrated passive/active load alleviation

et al. 2012

View full text Add to dashboard Cite

show abstract

“…Studies 4,5,6,7,8,9 had indicated the possibility of such a method of passive aerodynamic load alleviation with material-induced twist-bend coupling; 20° was determined to be the optimum angle. Other methods of twist-bend coupling have also been suggested 10,11,12,13 . The TX-100 also contained a fiberglass spar cap that terminated at the midspan of the blade.…”

Section: Fatigue Testing Was Conducted On Carbon Experimental and Twimentioning

confidence: 99%

Fatigue Testing of 9 m Carbon Fiber Wind Turbine Research Blades

Paquette

Dam

Hughes

et al. 2008

46th AIAA Aerospace Sciences Meeting and Exhibit

View full text Add to dashboard Cite

Three 9 m carbon fiber wind turbine blades have been designed through a research program initiated by Sandia National Laboratories. The individual designs feature such innovations as carbon spar caps, material-induced twist-bend coupling, and flatback airfoils, among others. All blades were constructed with conventional dry lay-up and VARTM infusion processes. Static tests of these blades were conducted at the National Wind Technology Center. The blades were subjected to flapwise loading to simulate the extreme wind loads expected for each design in a Class 2b wind site. The blades were loaded with a three-point whiffle-tree arrangement. Upon obtaining the predetermined test load, the blades were subsequently loaded to failure. Load, deflection, strain, and acoustic emissions were monitored throughout the experiments. All blades survived the specified test loads, with two designs exceeding it significantly. In addition, carbon strains of over 0.8% in both tension and compression were recorded in one of the tests. Finally, acoustic microphones were able to detect areas where damage was occurring, and indicated the beginnings of failure. This paper outlines the results of the structural tests that were conducted. Nomenclature VARTM = Vacuum Assisted Resin Transfer Method SNL = Sandia National Laboratories NWTC = National Wind Technology Center HP = High Pressure LP = Low Pressure

show abstract

“…Two basic approaches used either (1) sweep the blade in the plane of rotation, allowing that the aerodynamic loading to act on the outboard portions of the blade producing a substantial torque about the blade elastic axis, or (2) rotate some of the structural laminate fibers away from the spanwise direction inducing, in this way, a twist-flap coupling in the structure [8]. For a comprehensive review of prior research on aeroelastic tailoring of blades the interested reader is referred to Lobitz et al [9] Several works sponsored by the Sandia National Laboratories have been focusing the structural details of various blade designs to achieve twist-flap coupling [10,11,8]. All of these studies are conducted by performing a set of static analysis in which the fiber angle of the spar cap is modified in a discrete form changing from 5 to 20 or to 25 degrees.…”

Section: The Computer Program Vabs (Variational Asymptoticmentioning

confidence: 99%

Design blades of a wind turbine using flexible multibody modelling

Neto¹,

Yu²,

Ambrósio³

et al. 2009

REPQJ

View full text Add to dashboard Cite

Abstract.A methodology for the application of structural optimization to find the optimal layouts of composite blades, based on a multibody model of a wind turbine, is presented. VABS (Variational Asymptotic Beam Section) is used to compute the sectional constants for a generalized Timoshenko beam model. The gravity and inertia effects are taken into account as well as the aerodynamic force, which are calculated by the aerodynamic coefficients and transferred to the corresponding finite element nodes. The minimum lateral moment component at the blade root is found by using an optimization methodology that finds the optimal values for the fiber orientation of the composite spar of the blade. The computational efficiency and robustness of the optimal process relies on the accurate evaluation of the system sensitivities. In this work a general formulation for the computation of the first order analytical sensitivities based on the direct method is used. The direct method for sensitivity calculation is obtained by differentiating the equations defining the response of the structure with respect to the design variables. The equations of motion and sensitivities of the flexible multibody system are solved simultaneously and therefore the accelerations and velocities of the system and the sensitivities of the accelerations and of the velocities are integrated in time using a multi-step multi-order integration algorithm.

show abstract

Uncoupled and Twist-Bend Coupled Carbon-Glass Blades for the LIST Turbine

Cited by 5 publications

References 14 publications

Optimization‐based study of bend–twist coupled rotor blades for passive and integrated passive/active load alleviation

Optimization‐based study of bend–twist coupled rotor blades for passive and integrated passive/active load alleviation

Fatigue Testing of 9 m Carbon Fiber Wind Turbine Research Blades

Design blades of a wind turbine using flexible multibody modelling

Contact Info

Product

Resources

About