Vortex lattice method

About: Vortex lattice method is a research topic. Over the lifetime, 779 publications have been published within this topic receiving 9242 citations.

Wind Turbine Airfoil Performance Optimization using the Vortex Lattice Method and a Genetic Algorithm

Abstract: This paper examines the viability of using the combination of the vortex lattice method for aerodynamic performance prediction with a genetic algorithm for the optimization of the aerodynamic performance of horizontal axis wind turbine blades. The work described in this paper includes the adaptation of a vortex lattice code designed to predict propeller performance to wind turbine performance prediction and the optimization process including results for both single point and multipoint design optimization efforts. Background The economics of deploying large wind turbine farms as a substantial source of electrical power is driven in large part by the efficiency of power conversion from wind energy to rotational mechanical energy. In the 1920’s, Betz formulated the basic analysis for the limiting case for horizontal axis wind turbine efficiency and set up the guidelines for how windturbine efficiencies should be calculated. A modern explanation of the Betz analysis can be found in Reference 1. In the 1930’s Glauert applied classical aerodynamic methods to airplane propeller designs in an effort to optimize performance of the horizontal axis machine for propulsion. 2 In the 1970’s and 1980’s blade element and momentum theory models were developed and refined for modeling wind turbine performance 3-5 and the efficiency of these models made them ideally suited for the genetic algorithm optimization work performed in the 1990’s by Selig et al. 6 This method for optimizing horizontal axis wind turbines using genetic algorithms used an improved version of the momentum theory models and demonstrated a successful and efficient optimization strategy. Hampsey 1 improved upon the optimization efforts by using a B-spline approach for modeling the blades along with a panel method for performance prediction. In this important optimization using a relatively higher order method for aerodynamic prediction, the blade geometries were not modeled using traditional airfoil shape theory. In the development of performance prediction for sails, it has been shown that the prediction of aerodynamic loads using the vortex lattice method is often much more accurate than load predictions based on simpler momentum theory methods. As with the panel methods, computational efficiency necessary for optimization can be maintained with the vortex lattice method. 7 A vortex lattice method has been applied to ship propellers 8 and to airplane propellers and has been shown to accurately predict performance in appropriate applications. 9,10 The airplane propeller analysis reported in

Vortex Lattice Method Coupled with Advanced One-Dimensional Structural Models

Abstract: This work couples a Vortex Lattice Method, VLM, to a refined one-dimensional struc- tural model based on Carrera Unified Formulation, CUF Airfoil in-plane deformation and warping are introduced by enriching the displacement field over the cross-section of the wing Linear to fourth-order expansions are adopted and classical beam theories (Euler-Bernoulli and Timoshenko) are obtained as particular cases The VLM aero- dynamic theory is coupled via an appropriate adaptation of the Infinite Plate Spline method to the structural finite element model A number of wing configurations (by varying aspect ratio, airfoil geometry, dihedral, and sweep angle) and load cases are analyzed to assess both the calculation of aerodynamic loadings and the influence of in-plane airfoil deformation to the static response of the wing Comparison with shell results of commercial software such as MSC Nastran, which is taken as reference so- lution, is carried out and discussed The importance of higher-order models for an accurate evaluation of local and global response of aircraft wings is shown

Potential of Articulated Split Wingtips for Morphing-Based Control of a Flying Wing

Abstract: This paper investigates a novel method for the control of ‘morphing’ aircraft. The concept consists of a pair of articulated split wingtips, independently actuated and mounted on a baseline flying wing. The general philosophy behind the concept was that adequate control of a flying wing about its three axes could be obtained through local modifications of the dihedral angle at the wingtips, thus providing an alternative to conventional control eectors such as elevons and drag rudders. Preliminary computations with a vortex lattice model and subsequent wind tunnel tests demonstrate the viability of the concept, with individual and/or combined wingtip deflections producing multi-axis, coupled control moments. Nomenclature b wing span Cl, Cm, Cn rolling, pitching and yawing moment coecients CDi lift-induced drag coecient CLx lift coecient derivative w.r.t. parameter x Clx , Cmx , Cnx rolling, pitching and yawing moment coecient derivatives w.r.t. parameter x D, CD drag, drag coecient g gravitational acceleration L, CL lift, lift coecient p, q, r aircraft rotation rates in body or stability axes R turn radius Vcg flight speed W aircraft weight CG centre of gravity LE leading edge TE trailing edge VLM vortex lattice method Symbols angle of attack LA, RA left and right aft wingtip dihedral angles LF, RF left and right fore wingtip dihedral angles turn rate bank angle air density

Approximate Added-Mass Method for Estimating Induced Power for Flapping Flight

Abstract: A method that uses the added mass of vortex sheets was developed to estimate induced power in e apping e ight for birds and insects. This new method has advantages over existing methods. First, it is valid for e ights with any forward velocity. Second, this method can be used to determine the effects of most kinematic parameters of e apping wings on induced power, like the inclination of the stroke plane, amplitude of the e apping angle, and the mean e apping angle. For hovering e ight this method has the same accuracy as methods based on the Rankine ‐ Froude momentum theory or on vortex ring theory. When the forward velocity is large, this method agrees with the momentum theory for a e xed wing.