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Browsing by Author "Van Zyl, Louwrens H"

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Development of a sine-dwell ground vibration test (GVT) system

Author: Van Zyl, Louwrens H ; Wegman, Erik J Date: 27 Feb 2006 Knowledge of the natural modes of vibration of a structure is required to solve or avoid vibration and flexibility problems in industrial, automotive, aerospace and civil engineering applications. All new aircraft must undergo a flutter ... Read more
DLM for T-Tails

Author: Van Zyl, Louwrens H Date: Jun 2007 This paper describes the extension of the DLM to account for effects that are critical to the modelling of T-tail flutter. The boundary condition is made more general to account for yaw/dihedral and sideslip/dihedral coupling and the calculation ... Read more
Framework for T-tail flutter analysis

Author: Van Zyl, Louwrens H Date: Jun 2011 The flutter analysis of T-tail aircraft poses challenges that are unique to this configuration, including the fact that the unsteady air loads are dependent on the steady load distribution and static deformation of the aircraft. In particular, ... Read more
Holistic approach to flutter clearance using classical methods

Author: Van Zyl, Louwrens H Date: Sep 2006 Flutter clearance is usually regarded as a two step process: flutter analysis (including ground vibration testing, aerodynamic analysis and equation of motion solution), and flutter flight testing. The problem with this approach is that there ... Read more
Hybrid finite-volume-ROM approach to non-linear aerospace fluid-structure interaction modelling

Author: Mowat, AGB ; Malan, AG ; Van Zyl, Louwrens H ; Meyer, JP Date: Jun 2011 A fully-coupled partitioned fluid-structure interaction (FSI) scheme is developed for sub- and transonic aeroelastic structures undergoing non-linear displacements. The Euler equations, written in an Arbitrary Lagrangian Eulerian (ALE) ... Read more
Integration of the supersonic kernel function

Author: Van Zyl, Louwrens H Date: Nov 1994 The article discusses ways in which the integrals resulting from a zero-order discontinuous pressure distribution can be arranged in such a way that they can be solved by either normal quadrature or curve fitting followed by analytical ... Read more
Modifications to 25m2 target-aligned research Heliostat mirror panels

Author: Roos, TH ; Rossouw, F ; Van Zyl, Louwrens H Date: Sep 2009 Several heliostat mirror panels of the CSIR 25m2 target-aligned heliostat suffered corrosion-related failure, prompting a panel redesign. Two test samples of the new design were subjected to mechanical and thermal cycling tests in an attempt ... Read more
A pragmatic approach to including complex natural modes of vibration in aeroelastic analysis

Author: Van Zyl, Louwrens H Date: Sep 2015 Aeroelasticity is often described as the study of the interaction of inertial, elastic and aerodynamic forces that occur when an elastic body is exposed to a fluid flow (Wikipedia). The aim of a flutter analysis is to determine the speed above ... Read more
T-tail flutter analysis using Edge

Author: Van Zyl, Louwrens H ; Gledhill, Irvy MA Date: Nov 2011 A grid was generated with the base of the fin, i.e. the hinge line, on the axis of a cylindrical domain with a diameter of 2m. Due to the axial symmetry of the setup, rotation of the T-tail should not change the pressure distribution on the ... Read more
Unsteady panel method for complex configurations including wake modeling

Author: Van Zyl, Louwrens H Date: Jan 2008 The calculation of unsteady air loads is an essential step in any aeroelastic analysis. The subsonic doublet lattice method (DLM) is used extensively for this purpose due to its simplicity and reliability. The body models available with the ... Read more
Use of eigenvectors in the solution of the flutter equation

Author: Van Zyl, Louwrens H Date: Jul 1993 The use of eigenvectors to assign eigenvalues to modes for the p-k formulation of the flutter equation is described. The procedure has the potential to overcome some of the problems of the determinant iteration procedure to solve the flutter ... Read more

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Browsing by Author "Van Zyl, Louwrens H"

Browsing by Author "Van Zyl, Louwrens H"

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