Author: David W. Erickson (S.M.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 270
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Book Description
This research characterizes the performance of a centrifugal compressor stage with a special focus on the pipe diffuser. Two diffuser configurations are studied, one of which is a truncated version of the other. Experimental data acquired on a research compressor stage is interrogated along with a set of well-designed Reynolds-Averaged Navier Stokes computations, complemented by reduced order flow modeling. The fundamental performance-limiting flow mechanisms in the diffuser are identified and used to physically relate important geometry features and operating conditions to the observed compressor pressure rise, efficiency, and operability characteristics. Despite large differences in their geometry, the two diffuser configurations exhibit similar pressure recovery characteristics due to differences in exit nonuniformity and flow angle which result in similar effective area ratios. Variations in the diffuser pressure recovery coefficient with operating point are found to be most influenced by the diffuser inlet flow angle, and secondly by the inlet Mach number. The diffuser inlet flow angle has the primary effect of setting the diffuser inlet one-dimensional area ratio, increasing diffusion at high flow angles. In addition, the diffuser incidence angle influences the formation of counter-rotating vortex pairs that persist throughout the diffuser passage. Using a two-dimensional integral boundary layer model that is modified to accommodate three-dimensional effects as source terms, these secondary flows are shown to detrimentally impact the diffuser pressure rise capability by accumulating high loss flow along the diffuser wall near the plane of symmetry between the vortices. This contributes to the extent and location of a large diffuser passage separation, especially for the baseline diffuser. The impact of the vortices on the boundary layer growth rate is shown to scale inversely with diffuser aspect ratio. The major performance difference between the two diffuser configurations is that the truncated diffuser configuration experiences enhanced stall margin over the baseline diffuser at the design speed. These differences are traced to reduced secondary flows influence and thus reduced separation extent for the higher aspect ratio truncated diffuser. It is hypothesized that the onset of stall for the baseline diffuser configuration is initiated by the transition of the vortex location and corresponding passage separation between diffuser pressure and suction sides with increasing cusp incidence. Conversely, because the extent of the passage separation in the truncated diffuser is diminished due to the higher aspect ratio, the switch in separation side does not immediately initiate instability. The fact that secondary flows have a large influence on diffuser pressure rise capability and compressor stability is counter to conventional preliminary diffuser design approaches which neglect such 3D effects. The findings of this research may therefore be considered during preliminary design optimization to produce better-performing diffuser designs.
Author: Kenneth Arthur Gould
Publisher:
ISBN:
Category :
Languages : en
Pages : 137
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Book Description
(Cont.) A hypothesis has been put forward that increased diffusion associated with increased stage loading increases the impeller sensitivity to the downstream disturbance. The relative Mach number has been shown to set the chordwise distribution of the unsteady load on the blade. Unsteady blade loading has been computed through a quasi two-dimensional model in which an unsteady pressure boundary condition is imposed at the impeller exit to approximate the presence of the downstream diffuser. Results of this approximate model have been shown to yield unsteady loading characteristics that are in accord with the full three-dimensional unsteady model. An implied utility of this result is that a quasi-2D approximation could be used during the design phase to approximate the unsteady loading in a timeframe that is compatible with the design environment. The effect of unsteady flow on mass flow capacity of a fluid device is eliminated as a source for over-predictions in mass flow when a steady-state approximation is used.
Author: Rene Van den Braembussche
Publisher: John Wiley & Sons
ISBN: 1119424100
Category : Technology & Engineering
Languages : en
Pages : 606
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Book Description
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.
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 704
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Book Description
Author: Raj P. Chhabra
Publisher: CRC Press
ISBN: 1351646036
Category : Science
Languages : en
Pages : 1801
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Book Description
The CRC Handbook of Thermal Engineering, Second Edition, is a fully updated version of this respected reference work, with chapters written by leading experts. Its first part covers basic concepts, equations and principles of thermodynamics, heat transfer, and fluid dynamics. Following that is detailed coverage of major application areas, such as bioengineering, energy-efficient building systems, traditional and renewable energy sources, food processing, and aerospace heat transfer topics. The latest numerical and computational tools, microscale and nanoscale engineering, and new complex-structured materials are also presented. Designed for easy reference, this new edition is a must-have volume for engineers and researchers around the globe.
Author: Erwann Guillou
Publisher:
ISBN:
Category :
Languages : en
Pages : 371
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Book Description
Due to recent emission regulations, the use of turbochargers for force induction of internal combustion engines has increased. Actually, the trend in diesel engines is to downsize the engine by use of turbochargers that operate at higher pressure ratio. Unfortunately, increasing the rotational speed tends to reduce the turbocharger radial compressor range of operation which is limited at low mass flow rate by the occurrence of surge. In order to extent the operability of turbochargers, compressor housings can be equipped with a passive surge control device also known as ported shroud. This specific casing treatment has been demonstrated to enhance surge margin with minor negative impact on the compressor efficiency. However, the actual working mechanisms of the bypass system remain not well understood. In order to optimize the design of the ported shroud, it is then crucial to identify the dynamic flow changes induced by the implementation of the device to control instabilities. Experimental methods were used to assess the development of instabilities from stable, stall and eventually surge regimes of a ported shroud centrifugal compressor. Systematic comparison was conducted with the same compressor design without ported shroud. Hence, the full pressure dynamic survey of both compressors' performance characteristics converged toward two different and probably interrelated driving mechanisms to the development and/or propagation of unsteadiness within each compressor. One related the pressure disturbances at the compressor inlet, and notably the more apparent development of perturbations in the non-ported compressor impeller, whereas the other was attributed to the pressure distortions induced by the presence of the tongue in the asymmetric design of the compressor volute. Specific points of operation were selected to carry out planar flow measurements. At normal working, both standard and stereoscopic particle imaging velocimetry (PIV) measurements were performed to calculate the instantaneous and mean velocity fields at the inlet of the compressor. At incipient and full surge, phase-locked PIV measurements were added. In this work, satisfying characterization of the compressor inlet flow instabilities was obtained at different operational speeds. Combining transient pressure data and PIV measurements, the time evolution of the complex flow patterns occurring at surge was reconstructed and a better insight into the bypass mechanisms was achieved.
Author: Michael Casey
Publisher: Cambridge University Press
ISBN: 1108416675
Category : Science
Languages : en
Pages : 789
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Book Description
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.
Author: Fahua Gu
Publisher:
ISBN:
Category : Compressors
Languages : en
Pages : 484
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Book Description
Author: Hooman Rezaei
Publisher:
ISBN:
Category : Compressors
Languages : en
Pages : 422
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Book Description
Author: Theodore Gresh
Publisher: Newnes
ISBN: 0080529623
Category : Technology & Engineering
Languages : en
Pages : 215
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Book Description
Compressor Performance is a reference book and CD-ROM for compressor design engineers and compressor maintenance engineers, as well as engineering students. The book covers the full spectrum of information needed for an individual to select, operate, test and maintain axial or centrifugal compressors. It includes basic aerodynamic theory to provide the user with the "how's" and "why's" of compressor design. Maintenance engineers will especially appreciate the troubleshooting guidelines offered. Includes many example problems and reference data such as gas properties and flow meter calculations to enable easy analysis of compressor performance in practice. Includes companion CD with computer programs.M. Theodore Gresh has been with the Elliot Company in Jeannette, Pennsylvania, since 1975, initially working on the mechanical and aerodynamic design and application of centrifugal compressors. Unrivalled coverage of the theory and practical use of all kinds of compressors in industrial use from an industry-leading company sourceComplete subject reference and learning resource in one stop, suitable for newly graduated engineers and experienced professional reference useIncludes companion CD-ROM
