Teses / dissertações sobre o tema "Acoustique véhicule"
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Bongini, Estelle. "Modèle acoustique global et synthèse sonore du bruit d'un véhicule : application aux véhicules ferroviaires". Phd thesis, Université de Provence - Aix-Marseille I, 2008. http://tel.archives-ouvertes.fr/tel-00473940.
Texto completo da fonteCousson, Rémi. "Identification de sources acoustiques au passage d'un véhicule routier par imagerie acoustique parcimonieuse dans le domaine temporel". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI106/document.
Texto completo da fonteThe study detailed in this manuscript is part of the effort to characterize the noise emission from road vehicles. We wish to identify the noise sources of a moving vehicle, when driven on a roadway in real-world conditions, with roadside acoustic measurements. The current acoustic imaging methods do not provide sufficient performance on road vehicles. A state of the art led to the selection of an existing method, MSA-PSF, which consists in deconvolving signals from mobile sources in the frequency domain under certain assumptions, and was originally developed for aeroacoustics. This method is adapted here to the context of road vehicles. Then, an original approach is proposed in order to tackle the specific constraints of this context: CLEANT. This is an iterative method, performed in time domain with a wideband approach, which takes into account the effect of sources motion and includes two parameters designed to refine the result: the loop factor and the stopping criterium. A further version of the algorithm, including a frequency filter, is also proposed and shows significant improvement in identifying secondary sources in some particular cases. An interesting point of CLEANT is the availability of the sources reconstructed time signals, which enables other types of analysis, especially the use of the coherence with signals from on-board measurements in order to separate the contributions of uncorrelated sources. MSA-PSF and CLEANT are evaluated with numerical simulations and a set of indicators to measure their source localization and quantification performance. They are then tested in a controlled laboratory conditions experiment, using a moving source. This experiment represents a first application of the methods to a practical case, involving a linear motion, two simultaneous sources and different kinds of signals (tone and wideband). They are finally compared to the classical approach of moving source beamforming, within the frame of an experiment on a road vehicle, in real-world conditions. The original approach CLEANT yields very encouraging results, and is a clear improvement from the conventional beamforming, especially at low frequency for the tested cases. Applying it to a road vehicle in real-world conditions highlights a potentially troublesome behavior of the method, and the solution brought by CLEANT's frequency filtered version, or by adapting its various parameters. The coherence with reference signals to discriminate the physical origins of the sources is also tested and underlines the role of the short duration of the signals related to the sources passing-by context
Dubail, Patrick. "Caractérisation acoustique de sources d'origine mécanique dans un habitacle de véhicule". Lyon, INSA, 1999. http://www.theses.fr/1999ISAL0064.
Texto completo da fonteThis work deals with the localisation and the acoustical characterisation of mechanical sources in a truck cabin, through the identification of transfer paths. The analysis is based on a temporal approach. Since the main resonances of the system lead to a degradation of temporal resolution, a dual frequency band approach has been used. The study is split into four steps. The first two steps are concerned with a frequency range excluding the main resonances zone. 1. The first step of the processing consists in the spatiotemporal localisation of the transfer paths. Two linear arrays ('Mills cross') have been used for time domain beamforming. This geometry allows a three-dimensional localisation of angles of arrival and of paths lengths. 2. Then, these parameters are confirmed thanks to a geometric modelling obtained by ray tracing (accuracy better than 0. 5 cm and 1 °). 3. After the identification, the sources corresponding to the identified paths are characterized in the frequency range including the major resonances. Due to the complexity of the studied system and of the multiple paths structure, the separation of closed wave fronts needs additional processing: direct and inverse Radon transforms. 4. The last step of the processing is the accurate characterisation of the spectral content of the isolated wave fronts and, therefore, of the corresponding sources. The procedure, validated at first time on a model, has been applied to a truck cabin. The relative influences of the dashboard bottom and of the windscreen have been quantified in different frequency ranges
Vandernoot, Guillaume. "Caractérisation et optimisation de la restitution haute-fidelité en véhicule". Paris 6, 2001. http://www.theses.fr/2001PA066575.
Texto completo da fonteHamdi, Abdelbasset. "Exploration en conception mécanique préliminaire des compromis entre contraintes architecturales véhicule et performances vibro-acoustiques agrégées". Phd thesis, Ecole Centrale Paris, 2008. http://tel.archives-ouvertes.fr/tel-00376079.
Texto completo da fonteLa méthodologie proposée, nous permet d'engager des négociations entre les architectes de l'automobile et les ingénieurs mécaniciens sur le respect ou le non-respect de contraintes d'architecture d'un sous-système ou d'un organe, ainsi que sur l'atteinte des cibles du cahier des charges en ce qui concerne les performances vibro-acoustiques.
Le cadre méthodologique proposé se compose de cinq étapes : (1) la modélisation du problème de conception, comprenant (a) la modélisation des performances vibro-acoustiques et (b) la modélisation des contraintes d'architecture (2) la métamodélisation (approximation mathématique) du problème de conception résultant en utilisant les métamodèles de type kriging, (3) la formulation du problème de conception sous la forme d'un problème d'optimisation multi-objectifs, (4) la génération grâce au métamodèle de la frontière de Pareto de ce problème d'optimisation multi-objectif par la méthode des contraintes normales et normalisées, (5) une étape de négociation entre les contraintes d'architecture et les performances du sous-système mécanique.
Pour gérer le problème des contraintes d'architecture, dans la phase de conception préliminaire, nous introduisons une méthode pour exprimer, par un critère dit d'architecture, le respect ou le non-respect des contraintes géométriques. L'originalité de cette méthode consiste dans le fait de migrer l'étape de l'allocation de volumes enveloppes sous un système de CAO vers un système d'IAO plus accessible aux ingénieurs puisque c'est dans ce système qu'ils gèrent leurs modèles éléments finis.
Nous introduisons, en outre, une méthode d'agrégation des performances vibro-acoustiques d'un sous-système mécanique en un seul critère (indicateur) à valeur réelle. Cette technique permet une réduction efficace de la dimension importante d'un problème de conception lié à l'étude d'un sous-système mécanique avec des multiples performances vibro-acoustiques.
L'application de la méthodologie à un cas d'étude, dans le domaine automobile, a permis de démontrer son efficacité à améliorer sensiblement les performances vibro-acoustiques d'une caisse en blanc (caisse nue d'une automobile) tout en respectant des contraintes d'architecture serrées à cause d'un volume enveloppe alloué au groupe motopropulseur du véhicule.
Finalement, avec ce cadre méthodologique, les négociations entre les architectes et les ingénieurs ne sont plus fondées sur des jugements qualitatifs, mais elles sont à présent fondées sur des critères quantitatifs à la fois pour les contraintes d'architecture et les performances mécaniques.
Miqueau, Valentin. "Fiabilité de la méthode de prédiction vibro-acoustique SEA dans un contexte d'évaluation subjective du confort acoustique automobile". Electronic Thesis or Diss., Lyon, INSA, 2023. http://www.theses.fr/2023ISAL0102.
Texto completo da fonteAs the cabins of new vehicles become increasingly silent, the sound quality and the acoustic comfort have become key arguments for car manufacturers to destinguish themselves from their competitors. Research on sound perception currently relies on an experimental approach involving juries listening to signals recorded on prototypes. To avoid the costs associated with these elaborate setups, a digital approach is proposed in the present work. The results of a model based on the SEA method (Statistical Energy Analysis), developed by Saint-Gobain Research Compiègne, would be used to generate the signals for subjective experiences. It is already used to predict the impact of glazing changes on the interior noise level of a vehicle exposed to environmental noise. However, its use to assess the automotive acoustic comfort brought about by these changes raises several questions, which we address in this thesis : — How should we generate audio signals from the predicted sound pressure level? — Can we use the obtained signals to evaluate acoustic comfort inside the car cabin with the same effectiveness as with recordings measured in the vehicle? Firstly, a signal generation process based on data obtained from the numerical model was proposed and then validated through a perceptual experiment. Next, two other subjective assessments by a panel of judges revealed a similar trend in the annoyance experienced, for several glazing configurations, regardless of the origin of the sounds (simulated or measured). They did, however, highlight a discrepancy in the assessments when tempered glazing was introduced into the vehicle configurations. The window seals, which were not included in the model, were suspected of being the cause of this variation. Subsequently, the experimental examination of the vibro-acoustic behavior of a flat glass installed in the window seals allowed us to observe a dissipation contribution from the seals. This resulted in an increase of the acoustic insulation of the glazing. As this insulation characterizes the glazing in the model, its sensitivity to the dissipation contribution of the seals had to be incorporated into our numerical approach. Finally, after analyzing the dissipation mechanisms for both the glazing and the seals, a numerical model based on the finite element method was implemented. It predicts the acoustic insulation of the glazing as it should be integrated into the SEA numerical model in order to take account of the effect of the joints at the boundaries of the glass sample. Given that the calibration of the model at mid-high frequencies is the result of an empirical parameter search process, it is essential to consider revising the model and search method in future work
Périsse, Jocelyn. "Etude, conception et réalisation d'une suspension active d'un siège de véhicule routier pour l'amélioration du confort dynamique". Ecully, Ecole centrale de Lyon, 1997. http://www.theses.fr/1997ECDL0042.
Texto completo da fonteThis work deals with the study, the design and the realization on an active car seat suspension. It starts from the actual theoretical knowledge of active control of vibrations. In our case, we have applied an "active solution" to improve the comfort of car passenger. The comfort criteria (statical, postural, dynamical) which are now taken into account in the design of actual car seats, have been firstly reviewed. On this basis, we have chosen to develop an optimized suspension to solve the specific problem of vibratory isolation of the passenger
Parodi, Olivier. "Simulation hybride pour la coordination de véhicules hétérogènes au sein d'une flottille". Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2008. http://tel.archives-ouvertes.fr/tel-00373347.
Texto completo da fonteLa complexité des architectures de contrôle d'une part et les difficultés soulevées par le choix de stratégies de contrôle multi-véhicules d'autre part, rendent nécessaires la création de nouveaux outils de simulation permettant de tester et valider lois de commande et architectures de contrôle tout en détectant les inconsistances préliminaires des scenarios envisagés. L'objet de cette thèse est donc l'étude d'un outil de simulation collaboratif appelé THETIS.
Il s'agit d'un simulateur conçu avant tout pour aborder les problèmes liés au contexte de la flottille. Il est multi-véhicules hétérogènes puisqu'il permet de simuler par exemple, un scenario dans lequel un AUV (Autonomous Underwater Vehicle) et un ASV (Autonomous Surface Vehicle) interviennent simultanément. Les véhicules peuvent communiquer entre eux au sein de la simulation et les contraintes liées au milieu de propagation (interférences, bande passante, atténuation...) d'une part et à l'utilisation de matériel spécifique (temps de réveil, conflit émission/réception...) d'autre part sont prises en compte. L'architecture du simulateur est ouverte pour faciliter l'intégration et la mise à disposition pour tous, du travail de modélisation des différentes équipes possédant des compétences propres, tout en favorisant la réutilisabilité et la modularité de ces modèles. La capacité du système proposé à réaliser des simulations Hardware-In-The-Loop permet de tester et valider le comportement temporel du contrôleur. Par ailleurs ce simulateur est distribué afin de pouvoir étendre dynamiquement la puissance de calcul nécessitée par l'augmentation du nombre de véhicules et/ou la complexification des modèles, tout en respectant les contraintes temps-réel et le découplage temporel entre la commande et l'évolution des modèles dynamiques.
THETIS est donc un des seuls outils à l'heure actuelle répondant aux contraintes liées au contexte de la simulation de robots marins en flottille. Nous présentons des tests préliminaires mettant en œuvre un AUV de classe Taipan (développée au LIRMM en France) d'une part et un ASV Charlie (développé par l'ISSIA en Italie) d'autre part qui possèdent des architectures de contrôle différentes, et démontrons ainsi la faisabilité et la validité de notre approche.
Monet, Descombey Julien. "Modélisation numérique de multicouches poroélastiques pour une application automobile". Compiègne, 2009. http://www.theses.fr/2009COMP1811.
Texto completo da fonteThe present report is in line with an industrial thesis supported by the Roberval Laboratory of the University of Technology of Compiegne in partnership with the French car manufacturer Renault S. A. This thesis aims to develop, in an industrial environment, some methodologies intended for the improvement of the prediction of vibroacoustic calculations on large size coupled fluid-structure systems including poroelastic materials using commercial finite elements software especially dedicated for this purpose to perform the calculations. Acoustic and vibratory comfort within a passenger car is a very important field of research for the automotive industry, so much so that the awaited benefits are important in terms of sales. Because of a policy of reducing the number of prototypes, there has been strong interest from carmakers for numerical simulations for several years now. Moreover, recent upheavals (petroleum price, governmental penalties for polluting vehicles, economic crisis…) have radically changed customer behavior who now focus more on cheap, cleaner and more sober vehicles. The automotive industry has to adapt to this new demand by reducing vehicle weight, which makes it possible to decrease consumption and thus the polluting emissions. Soundproofing insulators are particularly targeted and new, more complex, solutions are proposed for testing. Numerical tools are now use to validate, even optimize, these new generations of insulators. The work presented in this thesis presents three research orientations: the finite elements modeling of these acoustical insulators made mainly of poroelastic materials, the use of commercial software as a computer aided design tool and the deployment of an improvement process for the numerical models while respecting the constraints inherent to a complex product developed in a rapidly changing industrial environment
Golay, Francis. "Caractérisation de l'émission acoustique des véhicules étendus par des sources ponctuelles équivalentes". Le Mans, 2010. https://tel.archives-ouvertes.fr/tel-00853308.
Texto completo da fonteGauthier, Mathieu. "Identification et hiérarchisation des sources et chemins de transfert vibro-acoustiques d'un véhicule récréatif". Mémoire, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/11245.
Texto completo da fonteRamamonjy, Aro. "Développement de nouvelles méthodes de classification/localisation de signaux acoustiques appliquées aux véhicules aériens". Thesis, Paris, CNAM, 2019. http://www.theses.fr/2019CNAM1234/document.
Texto completo da fonteThis thesis deals with the development of a compact microphone array and a dedicated signal processing chain for aerialtarget recognition and direction of arrival (DOA) estimation. The suggested global approach consists in an initial detection ofa potential target, followed by a DOA estimation and tracking process, along with a refined detection, facilitated by adaptivespatial filtering. An original DOA estimation algorithm is proposed. It uses the RANSAC algorithm on real-time time-domainbroadband [100 Hz - 10 kHz] pressure and particle velocity data which are estimated using finite differences and sums ofsignals of microphone pairs with frequency-dependent inter-microphone spacings. The use of higher order finite differences, or variants of the Phase and Amplitude Gradient Estimation (PAGE) method adapted to the designed antenna, can extend its bandwidth at high frequencies. The designed compact microphone array uses 32 digital MEMS microphones, horizontally disposed over an area of 7.5 centimeters. This array geometry is suitable to the implemented algorithms for DOA estimation and spatial filtering. DOA estimation and tracking of a trajectory controlled by a spatialization sphere in the Ambisonic domain have shown an average DOA estimation error of 4 degrees. A database of flying drones acoustic signatures has been set up, with the knowledge of the drone’s position in relation to the microphone array set out by GPS measurements. Adding artificial noise to the data, and selecting acoustic features with evolutionary programming have enabled the detection of an unknown drone in an unknown soundscape within 200 meters with the JRip classifier. In order to facilitate the detection and extend its range, the initial detection stage is preceded by differential beamforming in four main directions (north, south, east, west), and the refined detection stage is preceded by MVDR beamforming informed by the target’s DOA
Muzammel, Muhammad. "Développement d'un système d'avertissemment sonore, validé par EEG, basé sur des approches vision et acoustique pour la detection de véhicules approchants des véhicules moteur deux roues". Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCK019/document.
Texto completo da fonteIn many countries, motorcyclist fatality rate is much higher than that of other vehicle drivers. Among many other factors, motorcycle rear-end collisions are also contributing to these biker fatalities. Collision detection systems can be used to minimize these fatalities. However, most of the existing collision detection systems do not identify the type of potential hazard faced by motorcyclists. Every collision warning system used a distinctive collision detection technique, which limits its performance and makes it imperative to study its effectiveness. Unfortunately, no such work has been reported in that particular domain for motorcyclists. Therefore, it is important to study the physiological response of the motorcyclist against these collision warning systems. In this research, a rear end vehicle detection and classification method is presented for motorcyclists. For collision detection, vision technique and acoustic technique have been used. For visual and acoustic techniques, appearance features and power spectrum have been used, respectively, to detect the approaching vehicle at the rear end of the motorcycle. As for the vehicle classification, only an acoustic technique is utilized; an acoustic power spectrum and energy features are used to classify the approaching vehicles. Two types of datasets which are comprised of self-recorded datasets (obtained by placing a camera at the rear end of a motorcycle) and online datasets (for vision-based vehicle detection and for audio based vehicle classification techniques) are used for validation. Proposed methodology successfully detected and classified the vehicle for self-recorded datasets. Similarly, for online datasets, the higher true positive rate and less false detection rate has been achieved as compared to the existing state of the art methods. Moreover, an event-related potential (ERP) based physiological study has been performed on motorcyclists to investigate their responses towards the rear end collision warning system. Two types of auditory warnings (i.e., verbal and buzzer) are used for this warning system. To study the response of the motorcyclists, the N1, N2, P3, and N400 components have been extracted from the Electroencephalography (EEG) data. These introduced systems have shown positive effects at neural levels on motorcyclists and reduce their reaction time and attentional resources required for processing the target correctly. In summary, the proposed rear-end collision warning system with auditory verbal warnings significantly increases the alertness of the motorcyclist and can be helpful to avoid the possible rear-end collision scenarios
Leclercq, Damien. "Modélisation de la réponse électro-acoustique d'une structure couplée à une cavité en présence d'un écoulement turbulent". Compiègne, 1999. http://www.theses.fr/1999COMPA001.
Texto completo da fonteGolay, Francis. "CARACTERISATION DE L'EMISSION ACOUSTIQUE DES VEHICULES ETENDUS PAR DES SOURCES PONCTUELLES EQUIVALENTES". Phd thesis, Université du Maine, 2010. http://tel.archives-ouvertes.fr/tel-00853308.
Texto completo da fonteParodi, Olivier. "Simulation hybride pour la coordination de véhicules hétérogènes au sein d'une flottille". Montpellier 2, 2008. http://www.theses.fr/2008MON20198.
Texto completo da fonteEnnassiri, Hamza. "Analyse magnéto-vibroacoustique des machines synchrones discoides à commutation de flux dédiées aux véhiculex électriques hybrides". Thesis, Normandie, 2018. http://www.theses.fr/2018NORMLH36/document.
Texto completo da fonteThis PhD thesis deals with the issue of vibroacoustic emissions from the first design phases of electrical machines in order to have robust, reliable and above all efficient machines that meet the constraints in a wide range of applications and especially electrical vehicles. This manuscript is not only interested in the identification and highlighting the vibroacoustic problem, but above all to brought solutions and response elements to certain constraints. Knowing that the vibroacoustic problem is too vast and complex, this thesis focuses on vibroacoustic aspects of electromagnetic origin. To do so, the methods of noise reduction are presented but only the passive reduction solutions are used. These solutions are based on the design and optimization of efficient and less noisy electrical machines. This brings us back to the core of this work, which is the development of tools and multi-physics models combining the criteria of genericity, speed, accuracy and simplicity of coupling. In this context, several electric, magnetic, mechanical, thermal and acoustic models are presented. Different coupling strategies and modeling approaches are investigated. Conclusions are drawn each time according to the needs for the application use case
Loiseau, Paul. "Contrôle actif acoustique du bruit large bande dans un habitacle automobile". Thesis, Nantes, Ecole des Mines, 2016. http://www.theses.fr/2016EMNA0275/document.
Texto completo da fonteClassical methods used for noise reduction in cars are based on adjusting the mechanical properties: mass, stiffness and damping. They are qualified as passive and induce significative addition of weight for reducing low frequency noises. Active noise control is seen as a possible solution to achieve low frequency noise attenuation and weight reduction.The goal of this work is to evaluate achievable performances with such solution.Acoustic enclosures are known to be resonant systems of highorder. Obtaining a model of it, therefore requires a suitable identification method. The approach chosen is based on subspace methods. It processes data in the frequency domain for obtaining a continuous time model.The control problem derived from the specifications is a MIMO H1, multi-objective and multi-model problem with a strong stability constraint. Futhermore, actuators and sensors are not-colocated, and no measure of the disturbance is available. In order to precisely evaluate the achievable performances, this problem is solved using non smooth optimization.Such approach ensures the absence of pessimism, but requires an appropriate initialization and a parsimonious controller structure, because it does not ensure convergence toward the global optimum. The proposed methodology was validated in simulation and experimentally. It allows a precise evaluation and comparison of achievable performances according to the constraints on available measures and means of action
Hamdad, Hichem. "Recherche d'une description optimum des sources et systèmes vibroacoustiques pour la simulation du bruit de passage des véhicules automobiles". Thesis, Le Mans, 2018. http://www.theses.fr/2018LEMA1032/document.
Texto completo da fonteCurrently, to put a vehicle on market, car manufacturers must comply to a certification test of exterior noise. The regulation of the United Nations Economic Commission for Europe, ECE R51-03, specifies permissible levels a rolling motor vehicle can emit. This regulation is applied since July 1st, 2016, to replace the old regulation ECE R51-02 (test method change and tightening of permissible levels). The drastic reduction in noise levels will be done in 3 steps: from 74 dB (A) under the old regulation to 68 dB (A) in 2024. Therefore, manufacturers as well as their suppliers will face a great challenge to achieve this goal. The objective of this thesis is to develop an aid to the modeling of the pass-by noise of a vehicle, as called for in regulatory testing. The goal is to predict and evaluate accurately the noise emissions earlier in the vehicle development cycle, i.e. before the industrialization stage. We must then seek a trade-off between accuracy of estimates, sensitivity to parameters, robustness of the method and numerical efficiency
Conan, Ewen. "Traitements adaptés aux antennes linéaires horizontales pour la discrimination en immersion de sources Ultra Basse Fréquence". Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2017. http://www.theses.fr/2017IMTA0016/document.
Texto completo da fonteThis work focuses on acoustic source depth discrimination in the ultra-low frequency range (ULF, 0-500 Hz), using a horizontal line array. Depth discrimination is a binary classification problem, aiming to evaluate whether a received signal has been emitted by a source near the surface or by a submerged one. This could serve applications such as anti-submarine warfare or marine biology.The acoustic field generated by a ULF source can be described as a sum of modes, which properties depend on environment and source location. This modal propagation leads to modal dispersion: the different modes propagate at different velocities. This forbid the use of classical beamforming schemes. However, the horizontal array can be used as a spatial filter to estimate the properties of the modes: this is modal filtering. With a sufficient array length, modes are resolved, and the filtered modes can be used to localise the source using matched-mode processing. If the array is too short, the poorly-filtered modes cannot be used for localisation. Therefore, we are looking for a less precise but more robust information on source location, which leads to source depth discrimination.In this work, the poorly-filtered modes are used to decide whether the source is near the surface or submerged. Because some of the modes (the "trapped modes") are weakly excited by a surface source, we propose this decision relies on the estimation of the trapped energy ratio, i.e. the ratio of acoustic energy borne by trapped modes to the total acoustic energy. The problem of depth discrimination is then formulated as a binary hypothesis test on source depth. This physical formulation allows using Monte-Carlo methods and simulations to predict performance in a given context. This enables comparison between several estimators of the trapped energy ratio and the choice of a relevant threshold which this ratio is compared to in order to decide between the two hypotheses. The approach developped in the manuscript is validated by its application to marine experimental data. The results are consistent with the conclusions drawn from simulations. The proposed method enables the succesfull identification of both a surface source (the noise of a travelling ship) and a submerged source (a ULF source towed 30 m below the surface), using a 360-m horizontal array
Anthoine, Jérôme P. L. R. "Experimental and numerical study of aeroacoustic phenomena in large solid propellant boosters". Doctoral thesis, Universite Libre de Bruxelles, 2000. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211712.
Texto completo da fonteLarge SRM are composed of a submerged nozzle and segmented propellant grains separated by inhibitors. During propellant combustion, a cavity appears around the nozzle. Vortical flow structures may be formed from the inhibitor (Obstacle Vortex Shedding OVS) or from natural instability of the radial flow resulting from the propellant combustion (Surface Vortex Shedding SVS). Such hydrodynamic manifestations drive pressure oscillations in the confined flow established in the motor. When the vortex shedding frequency synchronizes acoustic modes of the motor chamber, resonance may occur and sound pressure can be amplified by vortex nozzle interaction.
Original analytical models, in particular based on vortex sound theory, point out the parameters controlling the flow-acoustic coupling and the effect of the nozzle design on sound production. They allow the appropriate definition of experimental tests.
The experiments are conducted on axisymmetric cold flow models respecting the Mach number similarity with the Ariane 5 SRM. The test section includes only one inhibitor and a submerged nozzle. The flow is either created by an axial air injection at the forward end or by a radial injection uniformly distributed along chamber porous walls. The internal Mach number can be varied continuously by means of a movable needle placed in the nozzle throat. Acoustic pressure measurements are taken by means of PCB piezoelectric transducers. A particle image velocimetry technique (PIV) is used to analyse the effect of the acoustic resonance on the mean flow field and vortex properties. An active control loop is exploited to obtain resonant and non resonant conditions for the same operating point.
Finally, numerical simulations are performed using a time dependent Navier Stokes solver. The analysis of the unsteady simulations provides pressure spectra, sequence of vorticity fields and average flow field. Comparison to experimental data is conducted.
The OVS and SVS instabilities are identified. The inhibitor parameters, the chamber Mach number and length, and the nozzle geometry are varied to analyse their effect on the flow acoustic coupling.
The conclusions state that flow acoustic coupling is mainly observed for nozzles including cavity. The nozzle geometry has an effect on the pressure oscillations through a coupling between the acoustic fluctuations induced by the cavity volume and the vortices travelling in front of the cavity entrance. When resonance occurs, the sound pressure level increases linearly with the chamber Mach number, the frequency and the cavity volume. In absence of cavity, the pressure fluctuations are damped.
Doctorat en sciences appliquées
info:eu-repo/semantics/nonPublished
Sidi, Babe Ahmed Sidia. "Modélisation électromagnétique par la méthode des transformations conformes d’une machine de traction synchrone à rotor bobiné en vue de l’étude de sources de bruit magnétique". Electronic Thesis or Diss., Compiègne, 2023. http://www.theses.fr/2023COMP2756.
Texto completo da fonteThis thesis focuses on the electromagnetic design of the wound salient pole rotor synchronous machine. This machine is used for the traction of electric vehicles made by Renault Group. To ensure comfort and customer satisfaction, electric motors designed for these vehicles must be silent. Thus, understanding and mastering the origins of magnetic noise and its reduction are essential in the pre-design phase of these motors. This research is being carried out within this scope. The purpose of this thesis is explained in the first part of this work, . Then, the origins of magnetic noise in electric motors are discussed. In addition, with a view to have a better understanding of noise and the sensitivity of the human ear to the sounds emitted, the fundamental concepts of acoustics are recalled. In order to choose the design approach of the motor, a state-of-the-art of electromagnetic design methods is presented. These different methods are evaluated on their ability to consider the doubly salient effect of the motor, the magnetic saturation and the shape of the rotor pole. Besides, the simplicity of the approach to be implemented is an additional characteristic. The first scientific contribution of this work is the analytical electromagnetic model of wound salient pole rotor synchronous machine using conformal mapping. This model made it possible to take into account the doubly salient effect of the machine for a vibroacoustic purpose. The radial and orthoradial magnetic stress components which cause the magnetic noise are evaluated and compared with those from finite elements simulations. The second scientific contribution is the consideration of magnetic saturation by the analytical model of the machine. This was achieved by introducing a step function of local magnetic saturation coefficients. These coefficients make it possible to reduce the flux density of the linear model in front of each stator tooth in order to correctly predict the flux density in saturated conditions of the machine. The last part of this work is dedicated to experimental testing. The vibroacoustic experimental analysis of the electric powertrain are presented. Measured acoustic pressure harmonics is compared to magnetic pressure harmonics calculated by the electromagnetic model and finite elements simulations. Different operating points of the machine are studied and the effect of the switching frequency on the main harmonics of magnetic and acoustic pressures is addressed