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.

Design of Fixed Wing Micro Air Vehicles

Abstract: The paper describes the methodology and computational design strategies used to develop a series of fixed wing micro air vehicles (MAVs) at the Ghent University. The emphasis of the research is to find an optimal MAV-platform that is bound to geometrical constraints but superior in its performance. This requires a multidisciplinary design optimisation but the challenges are mainly of aerodynamic nature. Key areas are endurance, stability, controllability, manoeuvrability and component integration. The highly three-dimensional low Reynolds number flow, the lack of experimental databases and analytical or empirical models of MAV-aerodynamics required fundamental research of the phenomena. This includes the use of a vortex lattice method, three-dimensional CFD-computations and a numerical propeller optimisation method to derive the forces and their derivatives of the MAV and propeller for performance and stability-related optimisation studies. The design method leads to a simple, stable and robust flying wing MAV-platform that has the agility of a fighter airplane. A prototype, the UGMAV25, was constructed and flight tests were performed. The capabilities of the MAV were tested in a series of successful flight manoeuvres. The UGMAV15, a MAV with a span of 15cm, is also developed to test flight-qualities and endurance at this small scale. With the current battery technology, a flight-time of at least one hour is expected.

Resistance in high-temperature superconductors

Abstract: The effects of magnetic fields on high-temperature superconductors are considered. Lines of flux of magnetic fields in superconductors consist of whirlpools of electric current, or vortices, movement of which can impede the flow of electrons and increase the resistance of superconductors. Vortex movement under various temperature and magnetic field conditions is critical in controlling supercurrent flow. Research on superconductors and the microscopic theory of superconductivity are briefly reviewed. Three magnetic states of superconductors are described and magnetic phase diagrams are presented. Current flow and its interaction with type II superconductors are described. Vortex behavior and the formation of vortex liquid due to vortex lattice melting in high temperature superconductors is discussed. Superconductor microstructure, composition, pinning, and the effects of these factors on vortex solids are considered. Resistance in vortex lattices and vortex glass is discussed. An understanding of these vortex states will assist in the engineering of better superconducting materials. 5 refs.

Prediction of Sheet Cavitation on a Rudder Subject to Propeller Flow

Abstract: This paper presents two numerical methods, a vortex lattice method (MPUF-3A) coupled with a finite volume method (GBFLOW-3D) and a boundary element method (PROPCAV), which are applied to predict time-averaged sheet cavitation on rudders, including the effects of the propeller as well as of the tunnel walls. The coupled MPUF-3A and GBFLOW-3D determines the velocity field due to the propeller within the fluid domain bounded by tunnel walls. MPUF-3A solves the potential flow around the propeller by distributing the line vortices and sources on the blade mean camber surface and determines the pressure distributions on the blade surface. GBFLOW-3D solves Euler equations with the body force terms converted from the pressure distributions on the blade surface and determines the total velocity field inside the fluid domain. The tunnel walls are treated as a solid boundary by applying the slip boundary condition, and the propeller blades are modeled via body forces. The two methods are solved iteratively until the forces on the blade converge. The cavity prediction on the rudder is accomplished via PROPCAV, which can handle back and face leading edge or mid-chord cavitation, in the presence of the three-dimensional flow field determined by the coupled MPUF-3A and GBFLOW-3D. The present method is validated by comparing the cavity shapes and the cavity envelope with those observed and measured in experiment and computed by another method.

RANS-Based Aerodynamic Shape Optimization of a Wing Considering Propeller–Wing Interaction

Abstract: The recent growth of interest in hybrid-electric and fully electric aircraft has led to a renewed focus on the design and optimization of propeller aircraft. Considering propeller–wing interaction ...