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.

Sail Optimization for Upwind Sailing: Application in a Tornado, the Olympic Class Catamaran

Abstract: A study of a boat's motion is carried out in order to analyze the aerodynamic properties of the optimal sail for obtaining the maximum velocity when sailing to windward. The mechanics study shows the optimal C L and C D for a given sail and how the shape of the aerodynamic polar of the sail should be. A parametrical analysis of the aerodynamics of a sail is then carried out varying the maximum camber, position of the maximum camber in the chord direction and position of the maximum camber in the mast direction. The parametric analysis is done numerically with a vortex lattice method (VLM) and experimentally in a wind tunnel. The results show that the influence of the relevant parameters studied can be reduced to the variation of two parameters, A and B, defining the polar of the sail, C D = B + A 2 C L 2; and the influence of parameters A and B on the maximum VMG obtainable are calculated.

Comparative study of wing lift distribution analysis using numerical method

Abstract: This research focuses on calculating the force distribution on the wings of the LSU 05-NG aircraft by several numerical methods. Analysis of the force distribution on the wing is important because the wing has a very important role in producing sufficient lift for the aircraft. The numerical methods used to calculate the lift force distribution on the wings are Computational Flow Dynamics (CFD), Lifting Line Theory, Vortex Lattice Method, and 3D Panel Method. The numerical methods used will be compared with each other to determine the accuracy and time required to calculate wing lift distribution. Because CFDs produce more accurate estimates, CFD is used as the main comparison for the other three numerical methods. Based on calculations performed, the 3D Panel Method has an accuracy that is close to CFD with a shorter time. 3D Panel Method requires 400 while CFD 1210 seconds with results that are not much different. While LLT and VLM have poor accuracy, however, a shorter time is needed. Therefore to analyze the distribution of lift force on the wing it is enough to use the 3D Panel Method due to accurate results and shorter computing time.

Computational and experimental investigations of the flow around cavitating hydrofoils

Abstract: The linearized boundary value problem of the two dimensional cavitating hydrofoil of general shape has been solved semi-analytically by inversion of the singular integral equations describing the unknown source and vortex distributions and the subsequent numerical integration over such known functions as the slope of the wetted foil surface. However, a more desirable method of solution is one which permits a natural extension to the solution of three dimensional wing and propeller cavitation. The method of discrete singularities, which has the advantage of being the two dimensional analog of the vortex lattice method, has been studied extensively for this reason. The current research included the extension of the method to solve the the most general problems of partial and supercavitation with the correct points of cavity detachment and the most physically acceptable closure model. The results of an experiment in the MHL water tunnel show good agreement with numerical results. The correlation between numerical and experimental cavitation numbers, along with the latest extensions to the analysis, is presented. Aknowledgements I would like to acknowledge the continuous and invaluable aid and advice provided by Dr. Spyros Kinnas during all phases of this research. In particular, his contributions to the analysis of face cavitation and midchord detachment were significant. The support, technical and otherwise, of Professor J.E. Kerwin and the rest of the propeller group is gratefully acknowledged. Finally, in the preparation of this document, the tedious job of proofing went to the dynamic tandem of Kelly Morris and Andrea Novacky. Without their intelligent suggestions, I would be much less satisfied. This research was sponsored in part by the Naval Sea Systems Command General Hydromechanics Research Program administered by the David W. Taylor Naval Ship Research and Development center, and in part by the Volvo Penta Corporation.

A routine method for the calculation of aerodynamic loads on a wing in the vicinity of infinite vortices

Abstract: : The vortex lattice method for the calculation of loads on a wing advancing in a uniform stream was extended to the case of a wing in the vicinity of infinite vortices. No experimental data or different treatments of the same problem being available in the literature in order to verify the accuracy of the present method, the results in the report had to be limited to checking their convergence with respect to the three parameters involved and investigating what conditions them. The problem being treated linearly, only the simple case of one infinite vortex at the midspan of a wing at zero angle of attack was tested, with the understanding that the method can be applied to more complicated cases once its convergence and its validity have been shown.

Introducción a la teoría VLM (Vortex Lattice Theory)

Abstract: Panel methods have been widely used in industry and are well established since the 1970s for aerodynamic analysis and computation. The Vortex Lattice Panel Method presented in this study comes across a sophisticated method that provides a quick solution time, allows rapid changes in geometry and suits well for aerodynamic analysis. The aerospace industry is highly competitive in design efficiency, and perhaps one of the most important factors on airplane design and engineering today is multidisciplinary optimization. Any cost reduction method in the design cycle of a product becomes vital in the success of its outcome. The subsequent sections of this article will further explain in depth the theory behind the vortex lattice method, and the reason behind its selection as the method for aerodynamic analysis during preliminary design work and computation within the aerospace industry. This article is analytic in nature, and its main objective is to present a mathematical summary of this widely used computational method in aerodynamics.