The Experts below are selected from a list of 14886 Experts worldwide ranked by ideXlab platform

Tooru Suita - One of the best experts on this subject based on the ideXlab platform.

  • Aerodynamics of a Transonic Centrifugal Compressor Impeller
    Journal of Turbomachinery, 2003
    Co-Authors: Seiichi Ibaraki, Tetsuya Matsuo, Hiroshi Kuma, Kunio Sumida, Tooru Suita
    Abstract:

    High-pressure ratio Centrifugal Compressors are applied to turbochargers and turboshaft engines because of their small dimensions, high efficiency, and wide operating range. Such a high-pressure ratio Centrifugal Compressor has a transonic inlet condition accompanied with a shock wave in the inducer portion. It is generally said that extra losses are generated by interaction of the shock wave and the boundary layers on the blade surface. To improve the performance of high-pressure ratio Centrifugal Compressor, it is necessary to understand the flow phenomena. Although some research works on transonic impeller flow have been published, some unknown flow physics are still remaining. The authors designed a transonic impeller, with an inlet Mach number about 1.3, and conducted detailed flow measurements by using laser doppler velocimetry (LDV). In the result, the interaction between the shock wave and tip leakage vortex at the inducer and flow distortion at the downstream of inducer were observed. The interaction of the boundary layer and the shock wave was not observed. Also, computational flow analysis was conducted and compared with experimental results.

  • Aerodynamics of a Transonic Centrifugal Compressor Impeller
    Volume 5: Turbo Expo 2002 Parts A and B, 2002
    Co-Authors: Seiichi Ibaraki, Tetsuya Matsuo, Hiroshi Kuma, Kunio Sumida, Tooru Suita
    Abstract:

    High pressure ratio Centrifugal Compressors are applied to turbochargers and turboshaft engines because of their small dimensions, high efficiency and wide operating range. Such a high pressure ratio Centrifugal Compressor has a transonic inlet condition accompanied with a shock wave in the inducer portion. It is generally said that extra losses are generated by interaction of the shock wave and the boundary layers on the blade surface. To improve the performance of high pressure ratio Centrifugal Compressor it is necessary to understand the flow phenomena. Although some research works on transonic impeller flow have been published, some unknown flow physics are still remaining. The authors designed a transonic impeller, with an inlet Mach number is about 1.3, and conducted detailed flow measurements by using Laser Doppler Velocimetry (LDV). In the result the interaction between the shock wave and tip leakage vortex at the inducer and flow distortion at the downstream of inducer were observed. The interaction of the boundary layer and the shock wave was not observed. Also computational flow analysis were conducted and compared with experimental results.Copyright © 2002 by ASME

R. S. Amano - One of the best experts on this subject based on the ideXlab platform.

  • Design System Development for a Fuel Cell Centrifugal Compressor
    International Journal of Fluid Mechanics & Thermal Sciences, 2019
    Co-Authors: Lei Chen, R. S. Amano
    Abstract:

    Centrifugal Compressors have been used in many areas of the machinery. The Centrifugal Compressor design is very complex, and a unique design system needs to be developed. A Centrifugal Compressor design system should be easy to use in interface and also flexible for inputs and outputs. The design tool also needs to be able to predicate the Compressor performance in a fairly accurate level. In this study, a Centrifugal Compressor design system which was developed in the past is further improved and developed. Current design system includes initial parameter studies, meanline analysis, throughflow calculation, impeller design, diffusser design, volute design, and structure analysis. The main improvements of the design system are adding the interface to allow users easy to use, adding the input and output capabilities and modifying few correlations. Current design system can predict the blade loading and Compressor performance better compared with original design system. A fuel cell low flow and low specific speed Centrifugal Compressor is designed by using current design system and the prototype Compressor is built. The Compressor performance tests were conducted. The experimental results are compared with numerical analysis. The experiments are in good agreements with calculations. The results demonstrate that the Centrifugal Compressor design is successful and the design system can be used for the future Centrifugal Compressor designs.

  • Study of the Flow in Centrifugal Compressor
    International Journal of Fluid Machinery and Systems, 2010
    Co-Authors: R. S. Amano
    Abstract:

    Reducing the losses of the tip clearance flow is one of the keys in an unshrouded Centrifugal Compressor design and development because tip clearances are large in relation to the span of the blades and also Centrifugal Compressors produce a sufficiently large pressure rise in single stage. This problem is more acute for a low flow high-pressure ratio impeller design. The large tip clearance would cause flow separations, and as a result it would drop both the efficiency and surge margin. Thus a design of a high efficiency and wide operation range low flow coefficient Centrifugal Compressor is a great challenge. This paper describes a recent development of high efficiency and wide surge margin low flow coefficient Centrifugal Compressor. A viscous turbomachinery optimal design method developed by the authors for axial flow machine was further extended and used in the Centrifugal Compressor design. The Compressor has three main parts: impeller, a low solidity diffuser and volute. The tip clearance is under a special consideration in this design to allow impeller insensitiveness to the clearance. A patented three-dimensional low solidity diffuser design method is used and applied to this design. The Compressor test results demonstrated to be successful to extend the low solidity diffusers to high-pressure ratio Compressor. The Compressor stage performance showed the total to static efficiency of the Compressor being about 85% and stability range over 35%. The test results are in good agreement with the design.

  • Development of a Low Flow Coefficient Single Stage Centrifugal Compressor
    International Journal for Computational Methods in Engineering Science and Mechanics, 2009
    Co-Authors: R. S. Amano
    Abstract:

    A low flow coefficient unshrouded Centrifugal Compressor would give up clearance in relation to the span of the blades, because Centrifugal Compressors produce a sufficiently large pressure rise in fewer stages. This problem is more acute for a low flow high-pressure ratio impeller. The large tip clearance would cause flow separations, and as a result it would drop both the efficiency and surge margin. Thus a design of a high efficiency and wide operation range for a low flow coefficient Centrifugal Compressor is a great challenge. This paper describes a new development of high efficiency and large surge margin low flow coefficient (0.145) Centrifugal Compressor. A viscous turbomachinery optimal design method developed by the authors for axial flow machine was further extended and used in this Centrifugal Compressor design. The new Compressor has three main parts: impeller, a low solidity diffuser, and volute. The tip clearance is under special consideration in this design to allow impeller insensitivenes...

  • The Development of a Centrifugal Compressor Impeller
    International Journal for Computational Methods in Engineering Science and Mechanics, 2009
    Co-Authors: R. S. Amano
    Abstract:

    An impeller is one of the key components of industrial Centrifugal Compressors and turbochargers. Aerodynamic and structure designs of the impeller are critical to the success of the whole Compressor stages. The requirements for efficiency and operating range of industrial Centrifugal Compressors and turbochargers have been increased dramatically compared with the situation in the past. The efficiency of a newly developed, low-pressure-ratio Centrifugal Compressor has reached the possible level of the machine. However, the efficiency level of an intermediate- and high-pressure ratio machine still has gaps between the current state-of-the-art and possible level. The challenge for Centrifugal Compressor design is to keep the efficiency level at state-of-the-art and increase the Compressor operating range. Increase of the Compressor operating range without sacrificing Compressor peak efficiency is difficult to achieve. The product globalization requires one product design, which can be used in all locations....

  • Study of the Flow in Centrifugal Compressor
    Volume 5: Microturbines and Small Turbomachinery; Oil and Gas Applications, 2009
    Co-Authors: R. S. Amano
    Abstract:

    An unshrouded Centrifugal Compressor would give up clearance very large in relation to the span of the blades, because Centrifugal Compressors produce a sufficiently large pressure rise in fewer stages. This problem is more acute for a low flow high-pressure ratio impeller. The large tip clearance would cause flow separations, and as a result it would drop both the efficiency and surge margin. Thus a design of a high efficiency and wide operation range for a Centrifugal Compressor is a great challenge. This paper describes a new development of high efficiency and a large surge margin flow coefficient of 0.145 Centrifugal Compressor. A viscous turbomachinery optimal design method developed by the authors for axial flow machine was further extended and used in this Centrifugal Compressor design. The new Compressor has three main parts: impeller, a low solidity diffuser and volute. The tip clearance is under a special consideration in this design to allow impeller insensitiveness to the clearance. A three-dimensional low solidity diffuser design method is proposed and applied to this design. This design demonstrated to be successful to extend the low solidarity diffusers to high-pressure ratio Compressor. The design performance range showed the total to static efficiency of the Compressor being about 85% and stability range over 35%. The experimental results showed that the test results are in good agreement with the design.© 2009 ASME

Seiichi Ibaraki - One of the best experts on this subject based on the ideXlab platform.

  • Aerodynamics of a Transonic Centrifugal Compressor Impeller
    Journal of Turbomachinery, 2003
    Co-Authors: Seiichi Ibaraki, Tetsuya Matsuo, Hiroshi Kuma, Kunio Sumida, Tooru Suita
    Abstract:

    High-pressure ratio Centrifugal Compressors are applied to turbochargers and turboshaft engines because of their small dimensions, high efficiency, and wide operating range. Such a high-pressure ratio Centrifugal Compressor has a transonic inlet condition accompanied with a shock wave in the inducer portion. It is generally said that extra losses are generated by interaction of the shock wave and the boundary layers on the blade surface. To improve the performance of high-pressure ratio Centrifugal Compressor, it is necessary to understand the flow phenomena. Although some research works on transonic impeller flow have been published, some unknown flow physics are still remaining. The authors designed a transonic impeller, with an inlet Mach number about 1.3, and conducted detailed flow measurements by using laser doppler velocimetry (LDV). In the result, the interaction between the shock wave and tip leakage vortex at the inducer and flow distortion at the downstream of inducer were observed. The interaction of the boundary layer and the shock wave was not observed. Also, computational flow analysis was conducted and compared with experimental results.

  • Aerodynamics of a Transonic Centrifugal Compressor Impeller
    Volume 5: Turbo Expo 2002 Parts A and B, 2002
    Co-Authors: Seiichi Ibaraki, Tetsuya Matsuo, Hiroshi Kuma, Kunio Sumida, Tooru Suita
    Abstract:

    High pressure ratio Centrifugal Compressors are applied to turbochargers and turboshaft engines because of their small dimensions, high efficiency and wide operating range. Such a high pressure ratio Centrifugal Compressor has a transonic inlet condition accompanied with a shock wave in the inducer portion. It is generally said that extra losses are generated by interaction of the shock wave and the boundary layers on the blade surface. To improve the performance of high pressure ratio Centrifugal Compressor it is necessary to understand the flow phenomena. Although some research works on transonic impeller flow have been published, some unknown flow physics are still remaining. The authors designed a transonic impeller, with an inlet Mach number is about 1.3, and conducted detailed flow measurements by using Laser Doppler Velocimetry (LDV). In the result the interaction between the shock wave and tip leakage vortex at the inducer and flow distortion at the downstream of inducer were observed. The interaction of the boundary layer and the shock wave was not observed. Also computational flow analysis were conducted and compared with experimental results.Copyright © 2002 by ASME

Jianzhong Xu - One of the best experts on this subject based on the ideXlab platform.

  • Research on Transonic Centrifugal Compressor Blades Tip Clearance Distribution of Vehicle Turbocharger
    SAE International Journal of Fuels and Lubricants, 2008
    Co-Authors: Yangjun Zhang, Xin Qian Zheng, Wei Lin Zhuge, Jianzhong Xu
    Abstract:

    ABSTRACT Flow induced by blades tip clearance is important for Centrifugal Compressor, especially for the high charging ratio transonic Centrifugal Compressor of vehicle. Based on three-dimensional CFD method, the flow fields of two opposite impeller blades tip clearance distribution Compressor stages with vaneless diffuser are analyzed. The law and action mechanism of tip clearance distribution effect on the high charging ratio transonic Centrifugal Compressor impeller and vaneless diffuser performance are researched. It is verified that the pressure ratio and efficiency of Compressor stage whose aft axial clearance height is smaller than fore radial clearance height is higher than that of Compressor stage whose aft axial clearance height is larger than fore radial clearance height. The smaller aft axial clearance height weakens the flow in aft half of impeller passage, improves impeller aft passage power input and obtains higher impeller pressure ratio and Compressor stage pressure ratio. The smaller aft axial clearance height gets higher efficiency because it reduces impeller aft blades tip clearance leakage vortices intensity and imposes the vortices breakdown and dissipation loss less in impeller passage exit and vaneless diffuser passage. The research of the impeller blades tip clearance distribution effect on vehicle transonic Centrifugal Compressor performance and flow structure lays a foundation for transonic Centrifugal Compressor flow control.

Yangjun Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Research and Design of a Centrifugal Compressor for Fuel Cell Turbocharger
    SAE Technical Paper Series, 2008
    Co-Authors: Xin Qian Zheng, Yangjun Zhang
    Abstract:

    ABSTRACT A low specific speed Centrifugal Compressor powered by an ordinary electric motor (20, 000 rpm) has been designed at Tsinghua University for air systems application of automotive fuel cell engines. Preliminary design characteristics have been concluded. Three-Dimensional Computational Fluid Dynamics (CFD) is used to investigate the flow field of the impeller. The characteristic curve and primary aerodynamic parameters of designed impeller are achieved. The experimental results indicate that the designed low specific speed Centrifugal Compressor has comparatively high efficiency and wide operating range. The highest efficiency and pressure ratio of the Centrifugal Compressor is up to 78% and 1.42, respectively. The designed low specific speed Centrifugal Compressor can meet the requirement of air systems of automotive fuel cell engines. Moreover, the low specific speed Centrifugal Compressor avoids difficulties of usage of high-speed electric motors in high specific speed Compressor.

  • Research on Transonic Centrifugal Compressor Blades Tip Clearance Distribution of Vehicle Turbocharger
    SAE International Journal of Fuels and Lubricants, 2008
    Co-Authors: Yangjun Zhang, Xin Qian Zheng, Wei Lin Zhuge, Jianzhong Xu
    Abstract:

    ABSTRACT Flow induced by blades tip clearance is important for Centrifugal Compressor, especially for the high charging ratio transonic Centrifugal Compressor of vehicle. Based on three-dimensional CFD method, the flow fields of two opposite impeller blades tip clearance distribution Compressor stages with vaneless diffuser are analyzed. The law and action mechanism of tip clearance distribution effect on the high charging ratio transonic Centrifugal Compressor impeller and vaneless diffuser performance are researched. It is verified that the pressure ratio and efficiency of Compressor stage whose aft axial clearance height is smaller than fore radial clearance height is higher than that of Compressor stage whose aft axial clearance height is larger than fore radial clearance height. The smaller aft axial clearance height weakens the flow in aft half of impeller passage, improves impeller aft passage power input and obtains higher impeller pressure ratio and Compressor stage pressure ratio. The smaller aft axial clearance height gets higher efficiency because it reduces impeller aft blades tip clearance leakage vortices intensity and imposes the vortices breakdown and dissipation loss less in impeller passage exit and vaneless diffuser passage. The research of the impeller blades tip clearance distribution effect on vehicle transonic Centrifugal Compressor performance and flow structure lays a foundation for transonic Centrifugal Compressor flow control.

  • Design of a Centrifugal Compressor With Low Specific Speed for Automotive Fuel Cell
    ASME Conference Proceedings, 2008
    Co-Authors: Xin Qian Zheng, Hong He, Yangjun Zhang, Zhiling Qiu
    Abstract:

    Centrifugal Compressors driven by electric motor are the promising type for fuel cell pressurization system. A low specific speed Centrifugal Compressor powered by an ordinary high-speed (about 25,000rpm) electric motor has been designed at Tsinghua University for automotive fuel cell engines. The experimental results indicate that the designed low specific speed Centrifugal Compressor has comparatively high efficiency and wide operating range. In the condition of designed speed (24,000rpm), the highest efficiency and pressure ratio of the Centrifugal Compressor is up to 70% and 1.6, respectively. The designed low specific speed Centrifugal Compressor can meet the requirement of air systems of automotive fuel cell engines preliminarily. Moreover, the low specific speed Centrifugal Compressor avoids difficulties of usage of ultra-high-speed electric motors (about 60,000rpm) in high specific speed Compressor. Based on the preliminary results of this Centrifugal Compressor, a new low specific speed Centrifugal Compressor with higher performances is being developed.