Searched for: subject%3A%22Turbulence%22
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Vogels, M.E.S. (author)
For flow simulation around (parts of) aerospace vehicles, aerospace industry needs CFD software. For users in industry, not only the functionality of the software is relevant. Timely availability and cost of the first version and later versions are other relevant factors. These factors are represented in the software characteristics timeliness,...
report 1997
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Vink, W.J. (author), de Jonge, J.B. (author)
The present report is part of a "Manual" on aircraft loads, that is being prepared by NLR. It contains a computer program, to be used in combination with "MATLAB4 for Windows" (Student Edition) software, to study aircraft loading due to turbulence. It includes a simple aircraft response model with two rigid and three flexible symmetric degrees...
report 1997
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de Jonge, J.B. (author), Hol, P.A. (author), van Gelder, P.A. (author)
report 1995
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van der Ven, H. (author)
In this TP a family of filters for Large Eddy Simulation with nonuniform filter widths is constructed that commute with differentiation up to any given order.
report 1994
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Noback, R. (author)
Aspects of the requirements for and the calculation of design loads due to atmospheric disturbances are discussed. Special attention has been paid to the relation between discrete gusts and continuous turbulence. It is recommended that a worst case gust model, as described in this report, be further developed.
report 1993
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Noback, R. (author)
A worst case gust shape has been derived for turbulence or gust patches, assuming only that the average spectrum of such patches is known. The maximum value of the response can be calculated quite easily. The result differs from the PSD-method. Some examples of worst case inputs and outputs are given, also for nonlinear systems.
report 1993
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Noback, R. (author)
The Deterministic Power-Spectral-Density method can be derived from the Design Envelope Analysis of the continuous P.S.D.-method. It provides a method to determine a deterministic function that gives a maximum response equal to the P.S.D.-design load for linear systems. The P.S.D.-design load is undefined for nonlinear systems. In this report a ...
report 1992
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Noback, N. (author)
The Deterministic Power-Spectral-Density-method has been derived directly from the continuous P.S.D.-method. It can be regarded as a "translation" from the frequency domain to the space or time domain. The critical gust profile, giving maximum response, is obtained directly. The D.P.S.D.-method gives the same results as the continuous P.S.D.-...
report 1992
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Noback, R. (author)
Equations for the response of an aircraft to two-dimensional vertical atmospheric turbulence have been derived, both for an aircraft regarded as a continuous system and for an aircraft split up into a number of panels. These equations have been applied to an aircraft model with two degrees of freedom of the size of the Fokker 100, respectively....
report 1991
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Noback, R. (author)
The derivation of one- two- and three-dimensional spectra and correlation functions for isotropic (atmospheric) turbulence and the mutual relations have been collected from various sources. Aircraft loads usually are determined using a one-dimensional turbulence description. In some cases a two- or even three-dimensional description might be...
report 1989
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Hoeijmakers, H.W.M. (author)
The physical aspects, the mathematical modeling, the development and application of computational methods for the simulation of vertical flows are described. The high-Reynolds number vortex flows considered are assumed to be steady, sub-critical and such that the structure of the flow is well-ordered and consists of thin shear layers and slender...
report 1989
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Noback, R. (author)
The Power Spectral Density (P.S.D.)-method is used to define design loads due to atmospheric turbulence. The design loads are calculated using linear transfer functions. These methods can not be used if the equations describing the behaviour of the aircraft are nonlinear. One method to define design loads for a nonlinear aircraft is by means of...
report 1989
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Noback, R. (author)
A method is described to generate a random Gaussian process with a power spectrum with fractional power, for example the von Karman spectrum for atmospheric turbulence. The method uses digital filtering of a white noise process and it is based on the use of fractional derivatives. An algorithm to generate the process is presented.
report 1988
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Noback, R. (author)
Measured time histories of atmospheric turbulence have been analysed. Distribution functions and exceedance curves of the turbulence and its derivative are presented. The load exceedance curves of various mathematical airplane models due to these turbulence patches have been calculated. Deviations of the properties of these patches from the...
report 1988
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de Jonge, J.B. (author)
The present course book has been prepared as lecture notes for a summer course given at the Technical University of Bandung (ITB) in the summer of 1984. This course took place within the framework of the TTA-79 Technical Assistance Project as agreed between the Governments of Indonesia and the Netherlands. The subjects of the course are listed...
report 1984
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de Bruin, A.C. (author)
The three dimensional flow field around delta wings with leading-edge vortex flow can be computed with panel methods. However, secondary flow separation may occur on the leeward surface of the wing. The associated free vortex sheet can be modeled in the potential flow calculation method, if the location of the secondary separation is provided by...
report 1983
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Noback, R. (author)
Historical reviews of the discrete gust and the continious gust concept, in relation to the present requirements, are given in this report. A comparison is made between the discrete gust method and the power spectral density method on the basis of simple airplane models. No direct relation between the two methods exists. The main cause of the...
report 1982
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Lindhout, J.P.F. (author), van den Berg, B. (author), Elsenaar, A. (author)
At the workshop nine participants presented the results of their calculations for a practical test case. The test case deals with the 3D turbulent boundary layer development, including separation, on the root section of a swept wing. The employed calculation methods comprise 3D integral methods as well as field methods. A short description of...
report 1981
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Noback, R. (author), Blaauboer, C. (author)
Design loads for nonlinear aircraft, i.e. aircraft with gust alleviation system or yaw dampler, cannot be established with the Power Spectral Density method. The only method available is by means of computer simvilation. Methods to approximate load exceedance curves of nonlinear aircraft are proposed in this report. For the derivation of the...
report 1980
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Oskam, B. (author)
The viscous flow around multi-component airfoils has been calculated by solving incompressible potential flow and boxindary layer problems iteratively. The potential flow problem is solved by a revised version of the 2D NLR panel method. A model transport equation of turbulent stress is employed to calculate the turbulent boundary layer. The...
report 1980
Searched for: subject%3A%22Turbulence%22
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