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This thesis offers new insights into the fluid flow behavior of automotive centrifugal compressors operating under near-stall conditions. Firstly it discusses the validation of three-dimensional computational fluid dynamics (CFD) unsteady simulations against acoustic experimental measurements using an original procedure based on plane wave pressure decomposition. It then examines the configuration of the CFD cases, highlighting the key parameters needed for a successful calculation. Moreover, it describes both the compressor mean and unsteady flow field from best-efficiency to near-surge operating points. Lastly, it provides readers with explanations of the various phenomena that arise when the mass flow rate is reduced and the compressor is driven to poor and noisy performance. Written for students, researchers and professionals who want to improve their understanding of the complex fluid flow behavior in centrifugal compressors, the thesis offers valuable practical insights into reducing the acoustic emissions of turbochargers.
Book Synopsis Predicting Flow-Induced Acoustics at Near-Stall Conditions in an Automotive Turbocharger Compressor by : Roberto Navarro García
Download or read book Predicting Flow-Induced Acoustics at Near-Stall Conditions in an Automotive Turbocharger Compressor written by Roberto Navarro García and published by Springer. This book was released on 2018-01-10 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis offers new insights into the fluid flow behavior of automotive centrifugal compressors operating under near-stall conditions. Firstly it discusses the validation of three-dimensional computational fluid dynamics (CFD) unsteady simulations against acoustic experimental measurements using an original procedure based on plane wave pressure decomposition. It then examines the configuration of the CFD cases, highlighting the key parameters needed for a successful calculation. Moreover, it describes both the compressor mean and unsteady flow field from best-efficiency to near-surge operating points. Lastly, it provides readers with explanations of the various phenomena that arise when the mass flow rate is reduced and the compressor is driven to poor and noisy performance. Written for students, researchers and professionals who want to improve their understanding of the complex fluid flow behavior in centrifugal compressors, the thesis offers valuable practical insights into reducing the acoustic emissions of turbochargers.
Downsizing modern automotive engines poses a challenge to turbocharger designs. Turbocharger compressors are required to provide a wide operating range with high-efficiency levels. The compressors are equipped with either passive or active casing treatments (ACTs) to achieve this goal. On the turbine side, the ever-increasing EGR flow into the engine demands an efficient scroll design that addresses both the performance and packaging limits.The present study conducts numerical aerodynamic and acoustic performance investigation of a turbocharger compressor equipped with a dual-slot active casing treatment (ACT) to widen the compressor's low and high flow rate operating limits independently. The first slot (surge-slot), positioned between the leading edge of the main and splitter blades, improves the surge margin of the compressor. Similar to the widely applied self-recirculating casing treatment, the surge slot removes stagnant fluid from the boundary-layer region of the inducer and delivers it to the impeller inlet when the compressor operates near the surge limit. The second slot (choke-slot), positioned downstream of the aerodynamic throat, increases the choke margin of the compressor. A new combination of loss models is proposed to predict the compressor performance, providing satisfactory results. A novel methodology is developed to estimate the full compressor map from CFD results by incorporating Greitzer's surge model. The compressor performance analysis revealed that the choke-slot closed configuration resulted in an isentropic efficiency penalty at higher compressor speeds. The efficiency penalty is addressed by optimizing the choke slot thickness to reduce the mass flow recirculating in the channel.On the other hand, the casing treatment provides an additional path for the unsteady compressor flow, increasing the noise level of the compressor. In this work, acoustic analogies are used to study the noise generated by different compressor casing treatment configurations. The transient aeroacoustic simulations are completed for both a choke-slot closed design near surge and a choke-slot open design near the maximum efficiency point. The simulation results revealed that the broadband and blade passing frequency (BPF) noise levels in the inlet and exit pipes decreased as the probe points moved away from the impeller.Further, the double inlet turbine performance is assessed numerically at even and uneven turbine inlet flows for three cases representing different engine operating conditions ranging from low load to full load. The CFD setup in this study is validated by using nine experimental data points with equal admissions at the two volute inlets. A significant amount of performance drop is observed when the turbine operates at uneven turbine inlet flow cases. The performance drop is more pronounced when the turbine operating point moves from low to high loads. Additionally, an energy audit of the turbine assembly is completed by estimating the local entropy production rate at eleven sub-regions. In all flow cases, the tip region losses dominate the impeller losses at even and uneven flows. The volute flow is affected sharply by the mass flow imbalance across the turbine inlets, most notably at high engine loads.In the last section of this work, the impact of volute design geometric parameters on the aerodynamic performance of the turbine with nozzle blades is explored by using a three-dimensional computational fluid dynamics method. The volute tongue angle, tongue clearance, and volute shape are assessed in detail to determine how they impact the turbine's isentropic efficiency and the pressure loss coefficient of the volute. The numerical results show that the optimal tongue angle is approximately 15℗ʻ for single-scroll volutes. The study results also indicate that higher tongue clearance improves turbine performance as it enhances flow development. Finally, symmetrical cross-sectional shapes boosted the turbine's aerodynamic performance in single-scroll turbines by uniformly distributing the volute exit flow from the hub to the shroud.
Book Synopsis Numerical Simulation and Modeling of a Turbocharger Compressor and Turbine to Improve Aerodynamics and Acoustics Performance by : Mekuannint M. Messele
Download or read book Numerical Simulation and Modeling of a Turbocharger Compressor and Turbine to Improve Aerodynamics and Acoustics Performance written by Mekuannint M. Messele and published by . This book was released on 2021 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: Downsizing modern automotive engines poses a challenge to turbocharger designs. Turbocharger compressors are required to provide a wide operating range with high-efficiency levels. The compressors are equipped with either passive or active casing treatments (ACTs) to achieve this goal. On the turbine side, the ever-increasing EGR flow into the engine demands an efficient scroll design that addresses both the performance and packaging limits.The present study conducts numerical aerodynamic and acoustic performance investigation of a turbocharger compressor equipped with a dual-slot active casing treatment (ACT) to widen the compressor's low and high flow rate operating limits independently. The first slot (surge-slot), positioned between the leading edge of the main and splitter blades, improves the surge margin of the compressor. Similar to the widely applied self-recirculating casing treatment, the surge slot removes stagnant fluid from the boundary-layer region of the inducer and delivers it to the impeller inlet when the compressor operates near the surge limit. The second slot (choke-slot), positioned downstream of the aerodynamic throat, increases the choke margin of the compressor. A new combination of loss models is proposed to predict the compressor performance, providing satisfactory results. A novel methodology is developed to estimate the full compressor map from CFD results by incorporating Greitzer's surge model. The compressor performance analysis revealed that the choke-slot closed configuration resulted in an isentropic efficiency penalty at higher compressor speeds. The efficiency penalty is addressed by optimizing the choke slot thickness to reduce the mass flow recirculating in the channel.On the other hand, the casing treatment provides an additional path for the unsteady compressor flow, increasing the noise level of the compressor. In this work, acoustic analogies are used to study the noise generated by different compressor casing treatment configurations. The transient aeroacoustic simulations are completed for both a choke-slot closed design near surge and a choke-slot open design near the maximum efficiency point. The simulation results revealed that the broadband and blade passing frequency (BPF) noise levels in the inlet and exit pipes decreased as the probe points moved away from the impeller.Further, the double inlet turbine performance is assessed numerically at even and uneven turbine inlet flows for three cases representing different engine operating conditions ranging from low load to full load. The CFD setup in this study is validated by using nine experimental data points with equal admissions at the two volute inlets. A significant amount of performance drop is observed when the turbine operates at uneven turbine inlet flow cases. The performance drop is more pronounced when the turbine operating point moves from low to high loads. Additionally, an energy audit of the turbine assembly is completed by estimating the local entropy production rate at eleven sub-regions. In all flow cases, the tip region losses dominate the impeller losses at even and uneven flows. The volute flow is affected sharply by the mass flow imbalance across the turbine inlets, most notably at high engine loads.In the last section of this work, the impact of volute design geometric parameters on the aerodynamic performance of the turbine with nozzle blades is explored by using a three-dimensional computational fluid dynamics method. The volute tongue angle, tongue clearance, and volute shape are assessed in detail to determine how they impact the turbine's isentropic efficiency and the pressure loss coefficient of the volute. The numerical results show that the optimal tongue angle is approximately 15℗ʻ for single-scroll volutes. The study results also indicate that higher tongue clearance improves turbine performance as it enhances flow development. Finally, symmetrical cross-sectional shapes boosted the turbine's aerodynamic performance in single-scroll turbines by uniformly distributing the volute exit flow from the hub to the shroud.
Aero and Vibroacoustics of Automotive Turbochargers is a topic involving aspects from the working fields of thermodynamics of turbomachinery, aerodynamics, rotordynamics, and noise propagation computation. In this broadly interdisciplinary subject, thermodynamics of turbomachinery is used to design the turbocharger and to determine its operating conditions. Aerodynamics is needed to study the compressor flow dynamics and flow instabilities of rotating stall and surge, which can produce growling and whining-type noises. Rotordynamics is necessary to study rotor unbalance and self-excited oil-whirl instabilities, which lead to whistling and constant tone-type noises in rotating floating oil-film type bearings. For the special case of turbochargers using ball bearings, some high-order harmonic and wear noises also manifest in the rotor operating range. Lastly, noise propagation computation, based on Lighthill’s analogy, is required to investigate airborne noises produced by turbochargers in passenger vehicles. The content of this book is intended for advanced undergraduates, graduates in mechanical engineering, research scientists and practicing engineers who want to better understand the interactions between these working fields and the resulting impact on the interesting topic of Aero and Vibroacoustics of Automotive Turbochargers.
Book Synopsis Aero and Vibroacoustics of Automotive Turbochargers by : Hung Nguyen-Schäfer
Download or read book Aero and Vibroacoustics of Automotive Turbochargers written by Hung Nguyen-Schäfer and published by Springer Science & Business Media. This book was released on 2013-01-06 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aero and Vibroacoustics of Automotive Turbochargers is a topic involving aspects from the working fields of thermodynamics of turbomachinery, aerodynamics, rotordynamics, and noise propagation computation. In this broadly interdisciplinary subject, thermodynamics of turbomachinery is used to design the turbocharger and to determine its operating conditions. Aerodynamics is needed to study the compressor flow dynamics and flow instabilities of rotating stall and surge, which can produce growling and whining-type noises. Rotordynamics is necessary to study rotor unbalance and self-excited oil-whirl instabilities, which lead to whistling and constant tone-type noises in rotating floating oil-film type bearings. For the special case of turbochargers using ball bearings, some high-order harmonic and wear noises also manifest in the rotor operating range. Lastly, noise propagation computation, based on Lighthill’s analogy, is required to investigate airborne noises produced by turbochargers in passenger vehicles. The content of this book is intended for advanced undergraduates, graduates in mechanical engineering, research scientists and practicing engineers who want to better understand the interactions between these working fields and the resulting impact on the interesting topic of Aero and Vibroacoustics of Automotive Turbochargers.
An introduction to the theory and engineering practice that underpins the component design and analysis of radial flow turbocompressors. Drawing upon an extensive theoretical background and years of practical experience, the authors provide descriptions of applications, concepts, component design, analysis tools, performance maps, flow stability, and structural integrity, with illustrative examples. Features wide coverage of all types of radial compressor over many applications unified by the consistent use of dimensional analysis. Discusses the methods needed to analyse the performance, flow, and mechanical integrity that underpin the design of efficient centrifugal compressors with good flow range and stability. Includes explanation of the design of all radial compressor components, including inlet guide vanes, impellers, diffusers, volutes, return channels, de-swirl vanes and side-streams. Suitable as a reference for advanced students of turbomachinery, and a perfect tool for practising mechanical and aerospace engineers already within the field and those just entering it.
Book Synopsis Radial Flow Turbocompressors by : Michael Casey
Download or read book Radial Flow Turbocompressors written by Michael Casey and published by Cambridge University Press. This book was released on 2021-06-10 with total page 789 pages. Available in PDF, EPUB and Kindle. Book excerpt: An introduction to the theory and engineering practice that underpins the component design and analysis of radial flow turbocompressors. Drawing upon an extensive theoretical background and years of practical experience, the authors provide descriptions of applications, concepts, component design, analysis tools, performance maps, flow stability, and structural integrity, with illustrative examples. Features wide coverage of all types of radial compressor over many applications unified by the consistent use of dimensional analysis. Discusses the methods needed to analyse the performance, flow, and mechanical integrity that underpin the design of efficient centrifugal compressors with good flow range and stability. Includes explanation of the design of all radial compressor components, including inlet guide vanes, impellers, diffusers, volutes, return channels, de-swirl vanes and side-streams. Suitable as a reference for advanced students of turbomachinery, and a perfect tool for practising mechanical and aerospace engineers already within the field and those just entering it.
Building on the success of an established series of successful conferences held every four years since 1978, 8th International Conference on Turbochargers and Turbocharging presents the latest technologies relating to engine pressure charging systems from international industry and academic experts in the field, covering new developments in compressors and novel intake systems; Improved models for cycle simulation; Electro boost systems; Industry trends and requirements; Turbines and mechanical aspects such as thermomechanical analysis, dynamics, and axial load capacity. Discusses the latest technologies relating to engine pressure charging systems Looks at mechanical aspects such as thermomechanical analysis, dynamics, and axial load capacity
Book Synopsis 8th International Conference on Turbochargers and Turbocharging by : IMechE
Download or read book 8th International Conference on Turbochargers and Turbocharging written by IMechE and published by Elsevier. This book was released on 2016-06-15 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt: Building on the success of an established series of successful conferences held every four years since 1978, 8th International Conference on Turbochargers and Turbocharging presents the latest technologies relating to engine pressure charging systems from international industry and academic experts in the field, covering new developments in compressors and novel intake systems; Improved models for cycle simulation; Electro boost systems; Industry trends and requirements; Turbines and mechanical aspects such as thermomechanical analysis, dynamics, and axial load capacity. Discusses the latest technologies relating to engine pressure charging systems Looks at mechanical aspects such as thermomechanical analysis, dynamics, and axial load capacity
Book Synopsis International Aerospace Abstracts by :
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1042 pages. Available in PDF, EPUB and Kindle. Book excerpt:
The book provides a survey of numerical methods for acoustics, namely the finite element method (FEM) and the boundary element method (BEM). It is the first book summarizing FEM and BEM (and optimization) for acoustics. The book shows that both methods can be effectively used for many other cases, FEM even for open domains and BEM for closed ones. Emphasis of the book is put on numerical aspects and on treatment of the exterior problem in acoustics, i.e. noise radiation.
Book Synopsis Computational Acoustics of Noise Propagation in Fluids - Finite and Boundary Element Methods by : Steffen Marburg
Download or read book Computational Acoustics of Noise Propagation in Fluids - Finite and Boundary Element Methods written by Steffen Marburg and published by Springer Science & Business Media. This book was released on 2008-02-27 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book provides a survey of numerical methods for acoustics, namely the finite element method (FEM) and the boundary element method (BEM). It is the first book summarizing FEM and BEM (and optimization) for acoustics. The book shows that both methods can be effectively used for many other cases, FEM even for open domains and BEM for closed ones. Emphasis of the book is put on numerical aspects and on treatment of the exterior problem in acoustics, i.e. noise radiation.
A comprehensive overview of fluid dynamic models and experimental results that can help solve problems in centrifugal compressors and modern techniques for a more efficient aerodynamic design. Design and Analysis of Centrifugal Compressors isacomprehensive overview of the theoretical fluid dynamic models describing the flow in centrifugal compressors and the modern techniques for the design of more efficient centrifugal compressors. The author — a noted expert in the field, with over 40 years of experience — evaluates relevant numerical and analytical prediction models for centrifugal compressors with special attention to their accuracy and limitations. Relevant knowledge from the last century is linked with new insights obtained from modern CFD. Emphasis is to link the flow structure, performance and stability to the geometry of the different compressor components. Design and Analysis of Centrifugal Compressors is an accessible resource that combines theory with experimental data and previous research with recent developments in computational design and optimization. This important resource Covers the basic information concerning fluid dynamics that are specific for centrifugal compressors and clarifies the differences with axial compressors Provides an overview of performance prediction models previously developed in combination with extra results from research conducted by the author Describes helpful numerical and analytical models for the flow in the different components in relation to flow stability, operating range and performance Includes the fundamental information for the aerodynamic design of more efficient centrifugal compressors Explains the use of computational fluid dynamics (CFD) for the design and analysis of centrifugal compressors Written for engineers, researchers and designers in industry as well as for academics specializing in the field, Design and Analysis of Centrifugal Compressors offers an up to date overview of the information needed for the design of more effective centrifugal compressors.
Book Synopsis Design and Analysis of Centrifugal Compressors by : Rene Van den Braembussche
Download or read book Design and Analysis of Centrifugal Compressors written by Rene Van den Braembussche and published by John Wiley & Sons. This book was released on 2019-04-08 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive overview of fluid dynamic models and experimental results that can help solve problems in centrifugal compressors and modern techniques for a more efficient aerodynamic design. Design and Analysis of Centrifugal Compressors isacomprehensive overview of the theoretical fluid dynamic models describing the flow in centrifugal compressors and the modern techniques for the design of more efficient centrifugal compressors. The author — a noted expert in the field, with over 40 years of experience — evaluates relevant numerical and analytical prediction models for centrifugal compressors with special attention to their accuracy and limitations. Relevant knowledge from the last century is linked with new insights obtained from modern CFD. Emphasis is to link the flow structure, performance and stability to the geometry of the different compressor components. Design and Analysis of Centrifugal Compressors is an accessible resource that combines theory with experimental data and previous research with recent developments in computational design and optimization. This important resource Covers the basic information concerning fluid dynamics that are specific for centrifugal compressors and clarifies the differences with axial compressors Provides an overview of performance prediction models previously developed in combination with extra results from research conducted by the author Describes helpful numerical and analytical models for the flow in the different components in relation to flow stability, operating range and performance Includes the fundamental information for the aerodynamic design of more efficient centrifugal compressors Explains the use of computational fluid dynamics (CFD) for the design and analysis of centrifugal compressors Written for engineers, researchers and designers in industry as well as for academics specializing in the field, Design and Analysis of Centrifugal Compressors offers an up to date overview of the information needed for the design of more effective centrifugal compressors.
Book Synopsis Aeroacoustics of Flight Vehicles by : Harvey H. Hubbard
Download or read book Aeroacoustics of Flight Vehicles written by Harvey H. Hubbard and published by . This book was released on 1991 with total page 620 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1987 with total page 1126 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
