References of "Léonard, Olivier"
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See detailOn-Line Validation of Measurements on Jet Engines Using Automatic Learning Methods
Dewallef, Pierre ULg; Léonard, Olivier ULg

in Proceedings od the 15th ISABE Conference (2001)

Nowadays, turbine engine tests are processed using an open loop, i.e. the measurements are verified and treated a posteriori, sometimes weeks or months after the end of the test. The purpose of the ... [more ▼]

Nowadays, turbine engine tests are processed using an open loop, i.e. the measurements are verified and treated a posteriori, sometimes weeks or months after the end of the test. The purpose of the present project is to develop a new methodology which enables real time detection of faulty measurements and the suppression of the source of these faults during the test. The validation of the measurements is achieved by a “robust” parameter identification [1]. Such a method is called robust in the sense that it can cope with 20 to 30% of faulty measurements. The robustness is insured by a distribution of the measurement noise, as introduced by Huber [7, 8], that takes into account the possibility of faults. The purpose of a parameter identification is to find the set of parameters which has most likely generated the measurements observed on the process. This leads to an optimisation problem that has to be solved for the parameters. The measurements are linked to the parameters through a non-linear model, leading to a large system of equations for modern jet engines. If no physical model of the process can be made available or if this model is too complex to allow real time validation, automatic learning methods may provide a solution: • either a mathematical representation is generated, directly based on the measurements (online learning), • or a database is first generated, based on the existing (but expensive) physical model, the database being subsequently used to build a statistical model (off-line learning). Neural networks seem to be very suitable for modeling the behavior of turbojets, avoiding the resolution of a time-consuming non-linear system. In this paper neural networks are tested to generate a mathematical representation of a single flow, single spool and variable geometry nozzle turbojet, from a data base of “measurements” generated by a physical model of the engine. Only the off-line learning approach is considered. [less ▲]

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See detailModelization, Development and Testing of a Variable Geometry Nozzle
Mignon, Anthony; Léonard, Olivier ULg

in Proceedings of the 5th Belgian National Congress on Theoretical and Applied Mechanics (2000)

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See detailCompressor and Turbine Blade Design by Optimization
Léonard, Olivier ULg; Rothilde, André; Duysinx, Pierre ULg

in Bloebaum, C. (Ed.) Proceedings of the 3rd World Congress of Structural and Multidisciplinary Optimization WCSMO3 (1999, May)

Compressor and turbine blade design involves thermodynamical, aerodynamical and mechanical aspects, resulting in an important number of iterations. Inverse methods and optimization procedures help the ... [more ▼]

Compressor and turbine blade design involves thermodynamical, aerodynamical and mechanical aspects, resulting in an important number of iterations. Inverse methods and optimization procedures help the designer in this long and eventually frustrating process. In this paper an optimization procedure is presented which solves two types of two-dimensional or quasi-three-dimensional problems: the inverse problem, for which a target velocity distribution is imposed, and a more global problem, in which the aerodynamic load is maximized. [less ▲]

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See detailAerodynamic and Mechanical Design of Compressor Blades Including Static Analysis
Adam, Olivier; Marin, Frédéric; Essers, Jean-André ULg et al

in Proceedings od the 3rd World Congress of Structural and Multidisciplinary Optimization (1999, May)

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See detailApplication of a three-dimensional inverse method to the design of a centrifugal compressor impeller
Demeulenaere, Alain; Léonard, Olivier ULg; Van den Braembussche, Rene

in Proceedings of the ASME Turbo Expo 1998 (1998, June)

ASME Paper 98-GT-127

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See detailDeveloppement d'une méthodologie d'optimisation aérodynamique et mécanique d'aubes de compresseurs
Adam, O.; Marin, F.; Thonon, C. et al

in RFM : Revue Française de Mécanique (1998), 4

Le projet décrit dans cet article a pour but de réaliser le dimensionnement des aubages d'un compresseur axial; pour ce faire, des codes de calcul aérodynamique et mécanique sont intégrés dans un ... [more ▼]

Le projet décrit dans cet article a pour but de réaliser le dimensionnement des aubages d'un compresseur axial; pour ce faire, des codes de calcul aérodynamique et mécanique sont intégrés dans un processus d'optimisation globale. Le transfert de données entre les différents modules utilisés est pris en charge par un logiciel gestionnaire de tâches, sur lequel est axée la méthode. Les codes aérodynamiques, basés sur l'approche classique quasi-tridimensionnelle, combinent une simulation d'écoulement dans le plan méridien ainsi qu'une succession d'écoulements en grilles d'aubes. Les codes mécaniques permettent une analyse à la fois statique et dynamique des aubages ; on notera en outre la possibilité de leur adjoindre des calculs d'impact ou de vérification de la durée de vie. Dans son état actuel, le code général permet d'optimiser la masse ou le rendement d'un étage de compression sur la base d'un calcul aérodynamique dans le plan méridien et d'une vérification des marges fréquentielles. [less ▲]

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See detailA Navier-Stokes Inverse Method Based on a Moving Blade Wall Strategy
Léonard, Olivier ULg; Demeulenaere, Alain

in Proceedings of the ASME Turbo Expo 1997 (1997, June)

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See detailBlade Analysis and Design Using an Implicit Flow Solver
Léonard, Olivier ULg; Rogiest, Pascal; Delanaye, Michel

in 2nd European Conference on Turbomachinery - Fluid Dynamics and Thermodynamics - Proceedings of the conference (1997, March)

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See detailA two-dimensional Navier-Stokes inverse solver for compressor and turbine blade design
Demeulenaere, A.; Léonard, Olivier ULg; Van den Braembussche, René

in Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy (1997), 211(4), 299-307

A two-dimensional viscous inverse method for the design of compressor and turbine blades is presented. It iteratively modifies an initial geometry until a prescribed pressure distribution is reached on ... [more ▼]

A two-dimensional viscous inverse method for the design of compressor and turbine blades is presented. It iteratively modifies an initial geometry until a prescribed pressure distribution is reached on the blade surface. The method solves the time-dependent Navier-Stokes equations in a numerical domain of which some boundaries (the blade walls) move during the transient part of the computation. The geometry modification algorithm is based on the transpiration principle: a normal velocity distribution is computed from the difference between the actual and prescribed pressure distributions, and is used to modify the blade shape. A time iteration is then performed on this new blade shape, taking into account the grid movement during the time stepping. A two-dimensional upwind finite-volume Navier-Stokes solver has been developed. The multiblock strategy allows for a selective concentration of the discretization points in the zones of higher gradients. Applications to turbine and compressor blade design illustrate the accuracy of the flow computation, the capabilities and efficiency of the inverse method. [less ▲]

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See detailOn the Existence of a Solution for Turbomachinery Blade Design
Demeulenaere, Alain; Léonard, Olivier ULg

in Proceedings of the 4th Belgian National Congress on Theoretical and Applied Mechanics (1997)

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See detailDéveloppement d’une méthodologie d’optimisation aérodynamique et mécanique d’aubes de compresseurs
Adam, Olivier; Thonon, Carole; Essers, Jean-André ULg et al

in Proceedings of the 4th Belgian National Congress on Theoretical and Applied Mechanics (1997)

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See detailApplication of a High-Order Upwind Finite-Volume Scheme to 2D Cascade Flows Using a Multi-Block Approach
Rogiest, Pascal; Léonard, Olivier ULg; Essers, Jean-André ULg

in Proceedings of the 12th ISABE Conference (1995)

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See detailPermeable Wall Concept for Transonic Blade Design
Léonard, Olivier ULg; Demeulenaere, Alain; Van den Braembussche, René

in Proceedings of the 3rd Belgian National Congress on Theoretical and Applied Mechanics (1994)

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See detailDesign Method for Subsonic and Transonic Cascade with Prescribed Mach Number Distribution
Léonard, Olivier ULg; Van den Braembusche, René

in Journal of Turbomachinery (1992), 114(3), 553-560

An iterative procedure for blade design, using a time marching procedure to solve the unsteady Euler equations in the blade-to-blade plane, is presented. A flow solver, which performs the analysis of the ... [more ▼]

An iterative procedure for blade design, using a time marching procedure to solve the unsteady Euler equations in the blade-to-blade plane, is presented. A flow solver, which performs the analysis of the flow field for a given geometry, is transformed into a design method. This is done by replacing the classical slip condition (no normal velocity component) by other boundary conditions, in such a way that the required pressure or Mach number distribution may be imposed directly on the blade. The unknowns are calculated on the blade wall using the so-called compatibility relations. Since the blade shape is not compatible with the required pressure distribution, a nonzero velocity component normal to the blade wall evolves from the new flow calculation. The blade geometry is then modified by resetting the wall parallel to the new flow field, using a transpiration technique, and the procedure is repeated until the calculated pressure distribution has converged to the required one. Examples for both subsonic and transonic flows are presented and show a rapid convergence to the geometry required for the desired Mach number distribution. An important advantage of the present method is the possibility to use the same code for the design and the analysis of a blade. [less ▲]

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See detailInverse Design of Compressor and Turbine Blades at Transonic Flow Conditions
Léonard, Olivier ULg; Van den Braembussche, René

in Proceedings of the ASME Turbo Expo 1992 (1992, June)

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See detailPermeable Wall Boundary Conditions For Transonic Airfoil Design
Léonard, Olivier ULg; Van den Braembussche, R. A.

in Proceedings od the First European Computational Fluid Dynamics Conference (1992)

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See detailDesign Method for Subsonic and Transonic Cascade with Prescribed Mach Number Distribution
Léonard, Olivier ULg; Van den Braembussche, René

in Proceedings of the ASME Turbo Expo 1991 (1991, June)

A iterative procedure for blade design, using a time marching procedure to solve the unsteady Euler equations in the blade-to-blade plane, is presented. A flow solver, which performs the analysis of the ... [more ▼]

A iterative procedure for blade design, using a time marching procedure to solve the unsteady Euler equations in the blade-to-blade plane, is presented. A flow solver, which performs the analysis of the flow field for a given geometry, is transformed into a design method. This is done by replacing the classical slip condition (no normal velocity component) by other boundary conditions, in such a way that the required pressure or Mach number distribution may be imposed directly on the blade. The unknowns are calculated on the blade wall using the so-called compatibility relations. Since the blade shape is not compatible with the required pressure distribution, a nonzero velocity component normal to the blade wall evolves from the new flow calculation. The blade geometry is then modified by resetting the wall parallel to the new flow field, using a transpiration technique, and the procedure is repeated until the calculated pressure distribution has converged to the required one. Examples for both subsonic and transonic flows are presented and show a rapid convergence to the geometry required for the desired Mach number distribution. An important advantage of the present method is the possibility to use the same code for the design and the analysis of a blade. [less ▲]

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See detailBlade Design and Analysis Using a Modified Euler Solver
Léonard, Olivier ULg; Van den Braembussche, René

in Proceedings of ICIDES-3 (1991)

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See detailSubsonic and Transonic Cascade Design
Léonard, Olivier ULg

in Van den Braembussche, René (Ed.) Inverse Methods for Airfoil Design for Aeronautical and Turbomachinery Applications (1990)

Detailed reference viewed: 26 (3 ULg)