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.

Cloth Simulation Algorithm Based on the Mass-Spring Model and the Non-planar Vortex Lattice Model

Abstract: With the development of computer technology, the simulation of fabrics has been widely used in many aspects of production and life. This paper focuses on the physical performance of a specific fabric under a quasi-steady-state flow field, which more realistically restores the movement of the fabric in low-speed airflow. It is combined the quasi-steady-state mechanical model based on aerodynamic theory with the classical structural mechanics model of cloth. By cyclically calculating the displacement and deformation of the cloth dot at different times, the cloth motion animation can be obtained. The experimental results show that through the combination with the Mass-Spring Model and the Non-planar Vortex Lattice Method, the fabric simulation effect with third dimension can be obtained.

Influences of airfoil profile on lateral-directional stability of aircraft with flying wing layout

Abstract: The purpose of this study is to analyze influence of airfoil profile on lateral-directional flying quality of flying wing aircraft. The lateral-directional stability is always insufficient for aircraft with the layout due to the absence of vertical stabilizer. A flying wing aircraft with double-swept wing is used as research object in the paper.,The 3D model is established for the aircraft with flying wing layout, and parametric modeling is carried out for airfoil mean camber line of the aircraft to analyze lateral-directional stability of the aircraft with different camber line parameters. To increase computational efficiency, vortex lattice method is adopted to calculate aerodynamic coefficients and aerodynamic derivatives of the aircraft.,It is found from the research results that roll mode and spiral mode have a little effect on lateral-directional stability of the aircraft but Dutch roll mode is the critical factor affecting flying quality level of such aircraft. Even though changes of airfoil mean line parameters can greatly change assessment parameters of aircraft lateral-directional flying quality, that is kind of change cannot have a fundamental impact on level of flying quality of the aircraft. In case flat shape parameters are determined, the airfoil profile has a limited impact on Dutch roll mode.,Influences of airfoil profile on lateral-directional flying quality of aircraft with double-swept flying wing layout are revealed in the thesis and some important rules and characteristics are also summarized to lay a theoretical basis for design of airfoil and flight control system of aircraft with the layout.

Aero-structural wing analysis using a vortex, lattice method coupled with an equivalent plate model

Abstract: The present work describes the integration of a non-linear Vortex Lattice Method (VLM) aerodynamic solver and an Equivalent Plate Model (EPM) structural solver, culminating in an Aero-Structural tool capable of analyzing wings. The aerodynamic and structural tools used in the Aero-Structural solver are described and validated, using experimental and numerical data. The aerodynamic model is expanded with the decambering approach, in order to allow for non-linear wing characteristics to be computed. This solver showed good agreement with experimental data both in linear and in non-linear regimes. The structural solver revealed good agreement with Finite-Element calculations, in both static load deformation and modal analysis. After describing and validating the two disciplines, the coupling between aerodynamic and structural solvers is described. A rectangular wing composed of skins, spars and ribs is analyzed using the present Aero-Structural solver. An experimental validation of the program developed is carried out. To accomplish this, a rectangular wing made with aluminum and PVC foam is built and tested in a wind tunnel. To measure wing deformations under aerodynamic loading, an in-house fully automated measurement system was developed using a laser measuring sensor and linear-guides actuated by stepper motors. The results showed a general good agreement between the deformation calculated with the numerical model and the data collected from wind tunnel testing. Some sources of experimental errors are identified and some enhancements are proposed.

Fast and accurate quasi-3D aerodynamic methods for aircraft conceptual design studies

Abstract: In this paper, recent developments in quasi-3D aerodynamic methods are presented. At their core, these methods are based on the Lifting-Line Theory and Vortex Lattice Method, but with a relaxed set of hypotheses, while also considering the effect of viscosity (to a certain degree) by introducing a strong non-linear coupling with two-dimensional viscous aerofoil aerodynamics. These methods can provide more accurate results compared to their inviscid classical counterparts and have an extended range of applicability with respect to the lifting surface geometry. Verification results are presented for both steady-state and unsteady flows, as well as case studies related to their integration into aerodynamic shape optimisation tools. The good accuracy achieved for relatively low computational time requirement makes quasi3D methods a solid choice for conducting conceptual level design and optimisation of lifting surfaces.

A study on the prediction of propeller slipstream and the numerical analysis of lifting surface

Abstract: In recent years, a highly advanced lifting surface method with high accuracy has been required in order to design the various types of propellers which demand high efficiency and to reduce ship vibration and noise.In this paper, an improved lifting surface procedure based on the vortex lattice method is presented. For the determination of a trailing vortex wake geometory, a numerical iterative procedure is described. The numerical results on propeller slipstream give a good agreement with the measured values by laser doppler velocimeter.The present method is applied to calculate the open water characteristics of a propeller. And a quasi-steady technique based on the present method is adopted to calculate the fluctuation of propeller forces and cavitation patterns behind the ship's wake field.The advantages of the present method are shown by comparing the numerical results with the experimental data of conventional and highly skewed propeller.