Maquette

Résumé

Une maquette est une représentation partielle ou complète d'un système ou d'un objet (existant ou en projet) afin d'en tester et valider certains aspects et/ou le comportement (maquette fonctionnelle), ou simplement à des fins ludiques (maquette de jeu) ou informatives (présentation pédagogique ou commerciale d'une réalisation ou d'un projet). La maquette peut être réalisée en deux ou trois dimensions, à une échelle donnée, le plus souvent réduite ou agrandie pour en faciliter la visualisation ou la manipulation. Elle peut être statique ou dynamique, et dans ce dernier cas on parlera alors de modélisme. Une maquette volumique est une représentation 3D à échelle généralement réduite d'une construction ou d'un appareil réel. L'aspect du réel peut être représenté en détail ou simplifié (maquette d'essais). Une maquette peut être l'ensemble des pièces servant à réaliser un modèle réduit, ou bien ce modèle terminé. Elle peut aussi être un modèle préalable servant à définir l'aspect ou l

Source officielle

https://fr.wikipedia.org/wiki/Maquette

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Cours associés (17)

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Séances de cours associées (20)

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Scale Model Evaluation and Optimization of Sodar Acoustic Baffles

Adrien Chabbey, Fernando Porté Agel

A 21: 1 scaled sodar, operating at 40 kHz, has been built and tested in the laboratory. Sodars, which use sound scattered by turbulence to profile the lowest few hundred meters of the atmosphere, need good acoustic shielding to diminish annoyance and to reduce unwanted reflections from nearby objects. Design of the acoustic shielding is generally inhibited by the difficulty of testing on full-scale systems and uncertainty as to accuracy of models. In contrast, the scale model approach described allows for "bench testing" of many designs under controlled conditions, and efficient comparison with models. Measured beam patterns from the scale model were compared with those from a numerical model based on the Kirchhoff integral theorem. Satisfactory agreement has allowed using the numerical model to optimize the acoustic shield design, both for the gross acoustic baffle geometry and for the geometry of rim modulations known as thnadners. Optimization was performed in the specific case of a scaled model of a commercial phased array sodar.

American Meteorological Society2015

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Design of a Hyperloop System MockUp

Tony Govoni, Malicia Leipold, Mario Paolone, Denis Tudor

The thorough development of the hyperloop system does require the availability of reduced-scale models. They can be used for the fast prototyping of various components, as well as for studying critical phenomena that takes place in this peculiar transportation system without the need to develop complex and expensive full-scale setups. In this respect, in this paper, we present a process for the optimal assessment of the scaling factor; it is to be used for the development of a reduced-scale hyperloop model, starting from the knowledge of the technical characteristics of its full-scale counterpart. The objective of the proposed process is the minimisation of the difference between the normalized power profiles associated with the reduced-scale and full-scale models of a hyperloop capsule traveling along a pre-defined trajectory with a pre-determined speed profile. By considering the hyperloop full-scale model as a reference, we propose a set of equations that link the above-mentioned metric with the constraints dictated by the kinematics of the hyperloop capsule, the capsule's battery-energy storage and propulsion systems, the capsule's aerodynamics, and the operating environmental conditions. We then derive a closed-form expression for the assessment of the optimal scaling factor and eventually use it to study the scaled-down version of an application example of a realistic hyperloop system.

IEEE2022

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To reduce CO2 emissions and tackle global warming, an increasing amount of electrical power consumed around the world must be obtained from renewable sources. Among these sources, hydropower has not only the advantage of leaving a very small carbon footprint, but also the ability to be flexible and compensate for the intermittent nature of other sources like solar and wind. For these qualities, a large number of new hydropower projects is foreseen in the near future. Hydropower still has a large potential for new projects worldwide. Furthermore, many already existing plants have also the possibility to modernize its facilities and increase its available installed capacity. For both new plants and modernization projects, thorough investigations are necessary to decide if the project is technically viable and economically relevant. Nevertheless, in the very early design stage, some key information regarding the properties of the future generating unit is often unknown or sometimes estimated with high uncertainty levels. One of these unknown aspects is the turbine efficiency: it can only be known with high accuracy after performing measurements on a reduced scale physical turbine model homologous to the future turbine prototype. The turbine complete characteristics of torque and discharge is also necessary for a proper dimensioning of the generating unit, as it impacts notably the overpressure in the water conduits and the overspeed of the rotating parts. Francis turbines operating at part load and full load conditions feature the so-called cavitation vortex rope in their draft tube cone. Therefore, two additional dynamic aspects can impact the performance of a Francis turbine generating unit: (1) a possible resonance between the hydraulic circuit first eigenfrequency and the excitation frequency from the vortex rope, and (2) the occurrence of high amplitude power swings and pressure surge induced by the cavitation vortex rope in unstable full load operating conditions. Currently, these two additional aspects usually remain completely unknown until the prototype enters into operation. This thesis objective is then to develop and validate new empirical models, testing and calculation procedures able to perform accurate predictions of a Francis turbine prototype dynamic behavior still in the early stage of a hydropower plant project. They can be used by engineers working in the design of Francis generating units to estimate with accuracy the final dynamic behavior of these units as a whole and, consequently, optimize the unit design to reduce costs and minimize risks related to the occurrence of undesired dynamic behavior of the cavitation vortex rope. The complete database of reduced scale physical model measurements available in the Laboratory for Hydraulic Machines (LMH) at the École Polytechnique Fédérale de Lausanne (EPFL) is used to construct empirical models able to estimate the turbine efficiency and complete characteristics. The obtained standard error in estimating peak efficiency values is then less than 1%. Extensive measurements and 1-D eigenvalue calculations are performed to better understand the dynamic behavior of the cavitation vortex in a specific test case. As a result, procedures to predict with accuracy part load resonance and full load instability are presented. These predictions can then be made soon after reduced scale model testing, i.e., usually years before the prototype enters into operation.

EPFL2019

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EPFL2019