Airfoil design: Finding the balance between design lift and structural stiffness

Bak, Christian; Gaudern, Nicholas; Zahle, Frederik; Vronsky, Tomas

doi:10.1088/1742-6596/524/1/012017

Cited by 10 publications

(3 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is to ensure that there is enough space for the wing box. Analogous to Bak et al (2014), a minimum local thickness of t(x/C)/t max > 85 % was enforced at two chordwise stations, namely at x 1 /C = 15 % and at x 2 /C = 40 %. This leaves space for a box length and height of at least l box /C = 25 % and h box /t max = 85 %, respectively.…”

Section: Integral Design Of Slat and Main Elementmentioning

confidence: 99%

Parametric slat design study for thick-base airfoils at high Reynolds numbers

et al. 2020

View full text Add to dashboard Cite

Abstract. Standard passive aerodynamic flow control devices such as vortex generators and gurney flaps have a working principle that is well understood. They increase the stall angle and the lift below stall and are mainly applied at the inboard part of wind turbine blades. However, the potential of applying a rigidly fixed leading-edge slat element at inboard blade stations is less well understood but has received some attention in the past decade. This solution may offer advantages not only under steady conditions but also under unsteady inflow conditions such as yaw. This article aims at further clarifying what an optimal two-element configuration with a thick main element would look like and what kind of performance characteristics can be expected from a purely aerodynamic point of view. To accomplish this an aerodynamic shape optimization procedure is used to derive optimal profile designs for different optimization boundary conditions including the optimization of both the slat and the main element. The performance of the optimized designs shows several positive characteristics compared to single-element airfoils, such as a high stall angle, high lift below stall, low roughness sensitivity, and higher aerodynamic efficiency. Furthermore, the results highlight the benefits of an integral design procedure, where both slat and main element are optimized, over an auxiliary one. Nevertheless, the designs also have two caveats, namely a steep drop in lift post-stall and high positive pitching moments.

show abstract

Section: Integral Design Of Slat and Main Elementmentioning

confidence: 99%

Parametric slat design study for thick-base airfoils at high Reynolds numbers

et al. 2020

View full text Add to dashboard Cite

show abstract

“…Other sensitivity analyses are found in the literature; Bak et al published a paper which studied the relation between aerodynamic and structural efficiency. Nilsson et al performed a sensitivity analysis to determine how the mean characteristics of wake flow, mean power production and thrust depend on the choice of airfoil data and blade geometry.…”

Section: Introductionmentioning

confidence: 99%

Global sensitivity analysis of the blade geometry variables on the wind turbine performance

2017

View full text Add to dashboard Cite

The need for implementing efficient blade designs gains relevance as wind turbine developments require longer blades. The design of blade geometry, traditionally divided in 2D airfoils and spanwise distributions, is usually addressed as an optimization problem. A correct identification of the design variables is crucial to avoid unnecessary computational cost or insufficient exploration of the design space. This paper deals with the identification of the design variables that affect the wind turbine performance.First, the number of design variables for an accurate airfoil representation is resolved. A methodology, based on statistical hypothesis testing applied to the airfoil approximation errors, is presented to assess the accuracy of types of B-splines.Second, the study is extended to chord and twist distributions besides airfoil geometry with the purpose of assessing the sensitive blade variables in the wind turbine performance. Global sensitivity analysis as multi-variable linear regressions and variance-based methods are used. Latin hypercube sampling is applied to generate efficient inputs. MATLAB-based code is developed to obtain outputs: annual energy production, maximum blade tip deflection, overall sound power level and blade mass.As result of the study, a list of non-affecting variables is deduced. These variables can be avoided in the optimization without loss of gain in the performance. The method is a powerful tool to analyse in a preliminary phase a design problem involving a high amount of variables and complex physical relations by means of combining different multi-disciplinar calculation codes and performing statistical treatments.

show abstract

“…For the most part, the airfoils all exhibit a more shallow suction surface compared to the pressure surface which aids to reduce the upper surface velocities thereby preventing premature flow separation under clean and soiled conditions. Furthermore, some of the studies use the sectional moment of inertia, I XX , to evaluate the structural performance of the airfoil, however a particular study has used more precise methods where the composite lay-up, and location and size of the structural spar are considered[82].…”

mentioning

confidence: 99%

The Multi-Objective Design of Flatback Wind Turbine Airfoils

Miller¹

View full text Add to dashboard Cite

With the ever increasing lengths of today's wind turbine rotor blades, there is a need for airfoils which are both aerodynamically, and structurally efficient. In this work, a multi-objective genetic algorithm coupled with XFOIL was developed to design flatback wind turbine airfoils. The effect of the aerodynamic evaluator, specifically lift-to-drag ratio, torque, and torque-to-thrust ratio, on the airfoil shape and performance was examined. Under the specified set of constraints and objectives, notable differences, particularly in the levels of lift and roughness insensitivity, were observed.Further analysis, employing the Taguchi method, was performed to determine how various parameters impact the design outcome. The obtained knowledge was used to design a wind turbine specific airfoil family which has comparable, or superior structural and aerodynamic performance as compared to airfoils found in the literature. A wind tunnel experimental set-up was developed at the Carleton University LowSpeed Wind Tunnel for the 2D testing of airfoils. Good agreement between the results obtained at Carleton University and other publicly available data indicates that the set-up is capable of producing meaningful data. A select airfoil, designed by the current author, was tested at Carleton University and its performance is compared to the numerical predictions of XFOIL. Differences in the stall and post-stall regions of the XFOIL predictions are highlighted, and emphasize the importance of wind tunnel testing in the airfoil design process.iii

show abstract

Airfoil design: Finding the balance between design lift and structural stiffness

Cited by 10 publications

References 3 publications

Parametric slat design study for thick-base airfoils at high Reynolds numbers

Parametric slat design study for thick-base airfoils at high Reynolds numbers

Global sensitivity analysis of the blade geometry variables on the wind turbine performance

The Multi-Objective Design of Flatback Wind Turbine Airfoils

Contact Info

Product

Resources

About