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Influence of Centrifugal Compressor Acoustic and Operating Parameters by Stator Geometry Modifications
Vacula, Jiří ; Vítek, Oldřich (referee) ; Babák, Martin (referee) ; Novotný, Pavel (advisor)
The increasing demands on the operational capabilities of rotating machines are mutually reflected in the ever-increasing computational capabilities. This makes it possible to analyse very detailed aerodynamic phenomena and to investigate the detailed effects of lesser-known aerodynamic principles. The standard aerodynamic design of a centrifugal compressor consists of an open impeller containing a smooth stator; however, the shape of the stator also contributes to the resulting parameters of a rotating machine. Thus, in this paper, the effect of stator geometry is first analysed qualitatively by analytical methods based on the analysis of the Navier-Stokes equation. Next, the influence of stator geometry is investigated by a Computational Fluid Dynamics (CFD) tool using circumferential casing treatment. The experimentally measured circumferential grooving of GT15 compressor shows that the quality of the treated surface can have a significant effect on the resulting performance of the rotating machine. Another measured casing treatment variant of the GTD2056 compressor shows an increase in efficiency of 0.5% and a marginal effect on aerodynamic noise. The relationship between the efficiency increases and losses is analysed using a viscous dissipation function that directly points to the influence of the flow field due to the geometric modifications of the stator and is shown to be largely conclusive for describing the losses in the impeller region.
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Computational modelling of aerodynamic noise caused by the car’s side mirror
Vobejda, Radek ; Hájek, Petr (referee) ; Švancara, Pavel (advisor)
The master’sthesis deals with numerical modelling of aerodynamic noisewhich arisesinside of the carcabin. In the first part ofthe thesis simplified model of geometry of the car and of the inside acoustic pressure arecreated. After that numerical analysis of created models of geometry are doneandvarious models of turbulenceare discussed. The results of these CFD simulationswhere then used for changing the model of geometry of the wing mirror. Outputs of these simulations were used for solving the numerical analysis of noise in the car cabin.
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Acoustic microclimate non-manufacturing buildings
Jelínek, Ondřej ; Andrys, Petr (referee) ; Rubina, Aleš (advisor)
This master´s thesis focuses on effect of acoustic microclimate in non-production buildings to human. Within elaboration this topic was made measurment acoustic power level and created protocols by valid technical standards and law. I dedicate to damping noise and aerodynamic noise in airconditioning in part topic analysis. The part aplication on real object deal with assessment current status and draft measure for improve acoustic ratio in laboratories in center of research located in Brno. That includes describe of air-cndition unit and development two variants and their rating.
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Use of Animal Biological Strategies to Reduce Vehicle Noise
Kovács, Gergő ; Vacula, Jiří (referee) ; Novotný, Pavel (advisor)
This bachelor thesis deals with the use of biological strategies of animals to reduce vehicle noise. First, the basic concepts of acoustics and the mentioned causes of noise in a car are clarified. A substantial part is devoted to a more detailed analysis of individual animals and their techniques. The main goal of this work is to analyze the noise reduction rate of these strategies and their potential use in transport, specifically in cars.
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Aerodynamic Borne Noise of Passenger Cars
Benka, Miroslav ; Prokop, Aleš (referee) ; Novotný, Pavel (advisor)
Among the most discussed problems in today's motor mechanics I considers the issue of the economy and also the emissions resulting from the use of cars. The trend is pushing emissions and operating costs down. There are several possible solutions to achieve greater efficiency. The most used is the so-called downsizing when the reduction of cylinder capacity while maintaining performance characteristics remain or even improve. This has the effect on the life of the engine and therefore some automakers try to refrain from this trend. In this thesis I will discuss the issue of vehicle noise, its resources focusing mainly on aerodynamic noise of a passenger car, the possibilities to reduce it and discuss how this market will develop in the future.
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An overview of types of the sound generated when driving a passenger car
Činčár, Vojtěch ; Novotný, Pavel (referee) ; Vacula, Jiří (advisor)
Noise pollution is serious problem, which is particularly affecting our lives. The dominant source of this pollution is road traffic noise, which includes the noise of aerodynamic and mechanical origin. In this bachelor´s thesis, in addition to the main noise sources of both origins while driving a car, a brief overview of acoustic quantities is also presented. The main part of the bachelor´s thesis is dedicated to aerodynamic noise and individual types of mechanical noise, such as the noise of car powertrain. In the end, the overall characteristics of the noise generated by a passenger car while driving are given.
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An overview of types of the sound generated when driving a passenger car
Činčár, Vojtěch ; Novotný, Pavel (referee) ; Vacula, Jiří (advisor)
Noise pollution is serious problem, which is particularly affecting our lives. The dominant source of this pollution is road traffic noise, which includes the noise of aerodynamic and mechanical origin. In this bachelor´s thesis, in addition to the main noise sources of both origins while driving a car, a brief overview of acoustic quantities is also presented. The main part of the bachelor´s thesis is dedicated to aerodynamic noise and individual types of mechanical noise, such as the noise of car powertrain. In the end, the overall characteristics of the noise generated by a passenger car while driving are given.
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Use of Animal Biological Strategies to Reduce Vehicle Noise
Kovács, Gergő ; Vacula, Jiří (referee) ; Novotný, Pavel (advisor)
This bachelor thesis deals with the use of biological strategies of animals to reduce vehicle noise. First, the basic concepts of acoustics and the mentioned causes of noise in a car are clarified. A substantial part is devoted to a more detailed analysis of individual animals and their techniques. The main goal of this work is to analyze the noise reduction rate of these strategies and their potential use in transport, specifically in cars.
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Computational modelling of aerodynamic noise caused by the car’s side mirror
Vobejda, Radek ; Hájek, Petr (referee) ; Švancara, Pavel (advisor)
The master’sthesis deals with numerical modelling of aerodynamic noisewhich arisesinside of the carcabin. In the first part ofthe thesis simplified model of geometry of the car and of the inside acoustic pressure arecreated. After that numerical analysis of created models of geometry are doneandvarious models of turbulenceare discussed. The results of these CFD simulationswhere then used for changing the model of geometry of the wing mirror. Outputs of these simulations were used for solving the numerical analysis of noise in the car cabin.
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Aerodynamic Borne Noise of Passenger Cars
Benka, Miroslav ; Prokop, Aleš (referee) ; Novotný, Pavel (advisor)
Among the most discussed problems in today's motor mechanics I considers the issue of the economy and also the emissions resulting from the use of cars. The trend is pushing emissions and operating costs down. There are several possible solutions to achieve greater efficiency. The most used is the so-called downsizing when the reduction of cylinder capacity while maintaining performance characteristics remain or even improve. This has the effect on the life of the engine and therefore some automakers try to refrain from this trend. In this thesis I will discuss the issue of vehicle noise, its resources focusing mainly on aerodynamic noise of a passenger car, the possibilities to reduce it and discuss how this market will develop in the future.
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