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Automotive turbo compressors generate high frequency noise in the air intake system. This sound generation is of importance for the perceived sound quality of luxury cars and may need to be controlled by the use of silencers. The silencers usually contain resonators with slits, perforates and cavities. The purpose of the work reported is to develop acoustic models for these resonators where relevant effects such as the effect of realistic mean flow on losses and possibly 3D effects are considered. An experimental campaign has been undertaken where the two-port matrices and transmission loss of four sample resonators has been measured without flow and for two different mean flow speeds (M=0.05 & M=0.1) using two source location technique. Models for the four resonators have been developed using a 1D linear acoustic code (SIDLAB) and a FEM code (COMSOL Multi-physics). Different models, from the literature, for including the effect of mean flow on the acoustic losses at slits and perforates have been discussed. Correct modeling of acoustic losses for resonators with complicated geometry is important for the simulation and development of new and improved silencers, and the present work contributes to this understanding. The measured acoustic properties compared well with the simulated model for almost all the cases.

The master thesis subject takes place in the automotive industry and specifically in the internal combustion engine area. The need of improving the efficiency of the engines leads to develop new technologies like turbo compressors. Some of the challenges to overcome are high rotational speed difficulties or extreme load and fatigue in the rotors. By design they are also prone to aerodynamic instabilities like compressor surge. These off design behaviors are not often studied by the manufacturers and therefore not so well known.  The aims are to understand, analyze and possible ameliorate the sources of compressor surge; to identify surge causes; to create a way to reproduce the phenomena with robustness and precision; to be able to study potential solutions to eliminate surge noises. A literature review has been carried out. This would give good metrics to identify surge cycles. Based on the theory developed by Fink et al. (1992) a simulation model has been generated, followed by a process of calibration carried out using data acquired during field experiments. This method uses a fully modifiable simulation model in order to be able to be adapted to a wide range of turbo compressors. The predicted data by the model shows a reasonable agreement with the experimental data. This allows to test control laws with a surge valve or a high pressure gas recirculating valve. The knowledge alongside the simulation would help the team to better apprehend the problem on the future engine generations and have means to avoid the unwanted surge phenomena to occur.

This diploma thesis is dedicated to a design of a reversing turbo-compressor. The thesis is divided into several parts. The introductory part includes the relevant theory and categorization of turbomachines. The second part describes the storage system the machine is designed for. A separate chapter is devoted to other examples of possible use of this machine. The next chapter provides a detail description of modes and individual parts of the machine. The most comprehensive chapter is then devoted to the design of the compressor, turbine calculation and design of integrated gearbox. The thesis also includes an annex, which contains the technical documentation.

L'étude vise à évaluer l'exposition professionnelle au bruit des travailleurs d'une plateforme gazière en Algérie et à mettre en évidence des déterminants influençant cette exposition. Des groupes d'exposition homogène (GEH) ont été constitués sur la base de ressemblances quant à l'exposition au bruit, aux titres d'emploi et aux lieux de travail. Deux stratégies d'échantillonnage ont été suivies, la première selon la norme internationale ISO 9612 : 2009 et la seconde selon la stratégie aléatoire de l'AIHA. Pour les deux approches, les niveaux de bruit (Lex, 8h, niveaux d'exposition au bruit pondéré (A) ajustés à une journée de travail de 8 heures) des opérateurs et des superviseurs étaient généralement > 85 dB(A) alors que pour les techniciens-tableau, les niveaux de bruit (Lex, 8h) étaient en tout temps < 85 dB(A). Pour les trois GEH du titre d'emploi des maintenanciers, il y a eu régulièrement des dépassements de la valeur de référence. Plusieurs travailleurs oeuvrant sur les plateformes gazières sont exposés à des niveaux importants de bruit et sont à risque de développer des problèmes auditifs. / The study aims to evaluate workers'noise exposure from an onshore gas platform in Algeria, and to emphasize the determinants influencing the exposure. Exposure groups were formed based on their work category and job location. Two sampling strategies were followed. The first was according to the international standard ISO 9612: 2009, and the second, according to the AIHA random strategy. For both strategies, the noise level (Lex, 8h, levels of exposure to noise ratio (A) for a working day of 8-hour) for operators and supervisors was usually > 85 dB(A) whereas the noise level for the technicians exposed in the distributed control system (DCS) was < 85 dB(A) at all times. The three HEG belonging to the maintenance technician group regularly exceeded the reference value of 85 dB(A). We concluded that employees working on the gas platform are exposed to significant noise level, and are at risk of developing hearing problems

L'étude vise à évaluer l'exposition professionnelle au bruit des travailleurs d'une plateforme gazière en Algérie et à mettre en évidence des déterminants influençant cette exposition. Des groupes d'exposition homogène (GEH) ont été constitués sur la base de ressemblances quant à l'exposition au bruit, aux titres d'emploi et aux lieux de travail. Deux stratégies d'échantillonnage ont été suivies, la première selon la norme internationale ISO 9612 : 2009 et la seconde selon la stratégie aléatoire de l'AIHA. Pour les deux approches, les niveaux de bruit (Lex, 8h, niveaux d'exposition au bruit pondéré (A) ajustés à une journée de travail de 8 heures) des opérateurs et des superviseurs étaient généralement > 85 dB(A) alors que pour les techniciens-tableau, les niveaux de bruit (Lex, 8h) étaient en tout temps < 85 dB(A). Pour les trois GEH du titre d'emploi des maintenanciers, il y a eu régulièrement des dépassements de la valeur de référence. Plusieurs travailleurs oeuvrant sur les plateformes gazières sont exposés à des niveaux importants de bruit et sont à risque de développer des problèmes auditifs. / The study aims to evaluate workers'noise exposure from an onshore gas platform in Algeria, and to emphasize the determinants influencing the exposure. Exposure groups were formed based on their work category and job location. Two sampling strategies were followed. The first was according to the international standard ISO 9612: 2009, and the second, according to the AIHA random strategy. For both strategies, the noise level (Lex, 8h, levels of exposure to noise ratio (A) for a working day of 8-hour) for operators and supervisors was usually > 85 dB(A) whereas the noise level for the technicians exposed in the distributed control system (DCS) was < 85 dB(A) at all times. The three HEG belonging to the maintenance technician group regularly exceeded the reference value of 85 dB(A). We concluded that employees working on the gas platform are exposed to significant noise level, and are at risk of developing hearing problems

The compressor for air supply to the fuel cell stack is a critical component of the balance of plant, especially for mobile applications. The main requirements of the compressor are the performance regarding pressure ratio, mass flow and efficiency at minimal size and weight. The turbo compressor technology is ideally suited to cope with these requirements. The lifetime requirement and the necessity of oil and particle free air supply advised to employ air bearings. The fuel cell air supply requirements are in conflict with the turbo compressor pressure ratio and mass flow characteristics. Possible solutions and their impact onto compressor design and fuel cell operation are described in this paper. The chosen system design approach considering all design aspects and its interactions during the design phase is beneficial in order to achieve the most lightweight and efficient air supply system for fuel cells. Experimental validation of an air bearing turbo compressor for a 100 kW fuel cell stack on an aerodynamic test rig verifies the predicted performance.

Air bearing radial turbo (also called centrifugal) compressors prevail in most mobile fuel cell air supply applications due to the small size and weight, the high efficiency and the oil- and maintenance free operation. An important aspect in mobile fuel cell applications is the vibration resistance of all system components, including the compressor, with vibration requirements up to 20 g in automotive applications. This paper gives the background of the air bearing vibration characteristics, depicting the dependencies of vibration resistance on inlet conditions and operating points. The critical operating conditions concerning vibration resistance are identified, and it is outlined how vibration requirements can be included in the design process of an air bearing turbo compressor. A visualization of vibration resistance in the commonly used compressor map is presented, allowing the fuel cell system integrator to take qualified decisions for the mechanical integration of the compressor concerning vibrations.

This diploma’s thesis analyzes the possibility of accumulation of thermal power plants in the Czech Republic. The thesis is divided into several parts. The first part describes the different types of storage power plants, the historical development of power storage for compressed air and the appropriateness of their location. The second part is devoted to the design of storage power plant for compressed air in South Moravia. In the next chapter, a calculation is made of all equipment storage power plant, including turbo-compressor, combustion chamber, combustion turbines, the volume of storage tanks and two heat exchangers. The last part is the economic analysis of the return on investment of such a project.