The Experts below are selected from a list of 2634 Experts worldwide ranked by ideXlab platform

L Guan - One of the best experts on this subject based on the ideXlab platform.

  • Multidisciplinary analysis transient flow effects on the Impeller in a semi-open centrifugal Impeller Stage
    2017 IEEE 21st International Conference on Computer Supported Cooperative Work in Design (CSCWD), 2017
    Co-Authors: Rong Xie, M. Hao, L Guan, Y. Shi
    Abstract:

    Centrifugal compressors present very complex unsteady characteristics under running. The influence of unsteady aerodynamic load on blades surface may be related to the blade fracture. This issue involves aerodynamics, engineering thermodynamics, structural mechanics, computational fluid dynamics, mathematics, etc. A multidisciplinary analysis method based on CFD software has been applied to predict the flow field in a semi-open Impeller Stage of a centrifugal compressor, to analyze 3D flow characteristics in the transient flow field and aerodynamic load on the blade surfaces. Mechanism with a high amplitude frequency was focused on. Combined with entropy distribution diagrams, the wake vortex shedding frequency and the interference frequency generated by low-energy groups were captured. Results indicate that the wake vortex shedding and the low-energy groups are the main factors causing high aerodynamic load on the Impeller blade. The large pressure pulsation generated by wake vortex shedding and low-energy group may greatly threaten the blade safety. This study provides beneficial references for the analysis of blade fracture causes in a semi-open Impeller Stage of a centrifugal compressor.

  • CSCWD - Multidisciplinary analysis transient flow effects on the Impeller in a semi-open centrifugal Impeller Stage
    2017 IEEE 21st International Conference on Computer Supported Cooperative Work in Design (CSCWD), 2017
    Co-Authors: L Guan
    Abstract:

    Centrifugal compressors present very complex unsteady characteristics under running. The influence of unsteady aerodynamic load on blades surface may be related to the blade fracture. This issue involves aerodynamics, engineering thermodynamics, structural mechanics, computational fluid dynamics, mathematics, etc. A multidisciplinary analysis method based on CFD software has been applied to predict the flow field in a semi-open Impeller Stage of a centrifugal compressor, to analyze 3D flow characteristics in the transient flow field and aerodynamic load on the blade surfaces. Mechanism with a high amplitude frequency was focused on. Combined with entropy distribution diagrams, the wake vortex shedding frequency and the interference frequency generated by low-energy groups were captured. Results indicate that the wake vortex shedding and the low-energy groups are the main factors causing high aerodynamic load on the Impeller blade. The large pressure pulsation generated by wake vortex shedding and low-energy group may greatly threaten the blade safety. This study provides beneficial references for the analysis of blade fracture causes in a semi-open Impeller Stage of a centrifugal compressor.

  • a simplified model of semi open Impeller Stage and analysis of its effects on the transient flow
    Applied Mechanics and Materials, 2014
    Co-Authors: L Guan, Zi Fu Lu
    Abstract:

    The centrifugal compressor is one type of vital energy conversion equipment and its unsteady characteristics are extremely complex in actual operation. A semi-open Impeller Stage with inlet guide vanes, an Impeller and a diffuser in a centrifugal compressor was concerned. For simulation of unsteady flow, the full-passage model of the integrate Stage requires much more simulating time and memory space, higher computer configuration. Therefore, a single-passage simplified model was established for unsteady analysis. The internal flow characteristics and aerodynamic load on the blade obtained by the simplified model were also compared with that by the full-passage model. The result shows that the precision of the simplified model can meet the engineering requirement. Compared with the full-passage model, the simplified model can give a relatively true reflection of the local flow characteristics and the aerodynamic load on blade surfaces, but it ignores the unevenness resulted from unsteadiness along circumferential direction. Only high-frequency information is retained in aerodynamic load analysis while low-frequency one is diluted. However, as far as the local flow pattern or high-frequency information resulted from unsteady effects is concerned, the simplified model provides the advantages of higher computational efficiency and lower hardware requirements.

Dara W. Childs - One of the best experts on this subject based on the ideXlab platform.

  • Rotordynamic Stability Predictions for Centrifugal Compressors Using a Bulk-Flow Model to Predict Impeller Shroud Force and Moment Coefficients
    Journal of Engineering for Gas Turbines and Power, 2010
    Co-Authors: Manoj K. Gupta, Dara W. Childs
    Abstract:

    An analysis is developed for a compressible bulk-flow model of the leakage path between a centrifugal-compressor Impeller’s shroud and its housing along the Impeller’s front and back sides. This development is an extension of analyses performed first by Childs (1989, ASME J. Vib. Acoust., Stress, Reliab. Des., 111, pp. 216–225) for pump Impellers. The bulk-flow model is used to predict reaction force and moment coefficients for the Impeller shroud. A labyrinth seal code developed by Childs and Scharrer ( 1986, ASME Trans. J. Eng. Gas Turbines Power, 108, pp. 325–331) is used to calculate the rotordynamic coefficients developed by the labyrinth seals in the compressor Stage and also provides a boundary condition for the shroud calculations. Comparisons between the measured shroud moment coefficients by Yoshida (1996, Proceedings of the 6th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery, 2, pp. 151–160) and model predictions show reasonable agreements for the clearance flow and reaction moments. For the conditions considered, low Mach number flow existed in the shroud clearance areas and compressible-flow and incompressible-flow models produced similar predictions. Childs’ model predictions for the direct damping and cross-coupled stiffness coefficients of a pump Impeller produced reasonable agreement; hence the present model was validated to the extent possible. A rotor model consisting of an overhung Impeller Stage supported by a nominally cantilevered rotor was analyzed for stability using the present bulk-flow model and an API standard Wachel–von Nimitz formula model (1981, J. Petrol. Technol., pp. 2252–2260). The bulk-flow model predicted significantly higher onset speeds of instability. Given that some compressors have been predicted to be comfortably stable using API standard Wachel–von Nimitz formula but have been unstable on the test stand, these results suggest that unidentified destabilizing forces and or moments are present in compressors. Seal rub conditions that arise from surge events and increase the seal clearances are simulated, showing that enlarged clearances increase the preswirl at the seals, thus increasing these seal’s destabilizing forces and reducing stability margins. These results are consistent with field experience. Predictions concerning the back shroud indicate that shunt-hole injection mainly acts to enhance stability by changing the flow field of the division wall or balance piston seals, not by influencing the back-shroud’s forces or moments. Effective swirl brakes at these seals also serve this purpose.

  • Rotordynamic Stability Predictions for Centrifugal Compressors Using a Bulk-Flow Model to Predict Impeller Shroud Force and Moment Coefficients
    Volume 5: Marine; Microturbines and Small Turbomachinery; Oil and Gas Applications; Structures and Dynamics Parts A and B, 2006
    Co-Authors: Manoj K. Gupta, Dara W. Childs
    Abstract:

    An analysis is developed for a compressible bulk-flow model of the leakage path between a centrifugal-compressor Impeller’s shroud and its housing along the Impeller’s front and back sides. This development is an extension of analyses performed first by Childs [15] for pump Impellers. The bulk-flow model is used to predict reaction force and moment coefficients for the Impeller shroud. A labyrinth seal code developed by Childs and Scharrer [21] is used to calculate the rotordynamic coefficients developed by the labyrinth seals in the compressor Stage and also provides a boundary condition for the shroud calculations. Comparisons between the measured shroud moment coefficients by Yoshida et al. [18] and model predictions show reasonable agreements for the clearance flow and reaction moments. For the conditions considered, low Mach number flow existed in the shroud clearance areas and compressible-flow and incompressible-flow models produced similar predictions. Childs’ model predictions for the direct damping and cross-coupled stiffness coefficients of a pump Impeller produced reasonable agreement; hence the present model was validated to the extent possible. A rotor model consisting of an overhung Impeller Stage supported by a nominally cantilevered rotor was analyzed for stability using the present bulk-flow model and an API standard Wachel-formula model [10]. The bulk-flow model predicted significantly higher onset speeds of instability. Given that some compressors have been predicted to be comfortably stable using API standard Wachel-formula but have been unstable on the test stand, these results suggest that unidentified destabilizing forces and or moments are present in compressors. Seal rub conditions that arise from surge events and increase the seal clearances are simulated, showing that enlarged clearances increase the preswirl at the seals, thus increasing these seal’s destabilizing forces and reducing stability margins. These results are consistent with field experience. Predictions concerning the back shroud indicate that shunt-hole injection mainly acts to enhance stability by changing the flow field of the division wall or balance piston seals, not by influencing the back-shroud’s forces or moments. Effective swirl brakes at these seals also serves this purpose.Copyright © 2006 by ASME

Y. Shi - One of the best experts on this subject based on the ideXlab platform.

  • Multidisciplinary analysis transient flow effects on the Impeller in a semi-open centrifugal Impeller Stage
    2017 IEEE 21st International Conference on Computer Supported Cooperative Work in Design (CSCWD), 2017
    Co-Authors: Rong Xie, M. Hao, L Guan, Y. Shi
    Abstract:

    Centrifugal compressors present very complex unsteady characteristics under running. The influence of unsteady aerodynamic load on blades surface may be related to the blade fracture. This issue involves aerodynamics, engineering thermodynamics, structural mechanics, computational fluid dynamics, mathematics, etc. A multidisciplinary analysis method based on CFD software has been applied to predict the flow field in a semi-open Impeller Stage of a centrifugal compressor, to analyze 3D flow characteristics in the transient flow field and aerodynamic load on the blade surfaces. Mechanism with a high amplitude frequency was focused on. Combined with entropy distribution diagrams, the wake vortex shedding frequency and the interference frequency generated by low-energy groups were captured. Results indicate that the wake vortex shedding and the low-energy groups are the main factors causing high aerodynamic load on the Impeller blade. The large pressure pulsation generated by wake vortex shedding and low-energy group may greatly threaten the blade safety. This study provides beneficial references for the analysis of blade fracture causes in a semi-open Impeller Stage of a centrifugal compressor.

Manoj K. Gupta - One of the best experts on this subject based on the ideXlab platform.

  • Rotordynamic Stability Predictions for Centrifugal Compressors Using a Bulk-Flow Model to Predict Impeller Shroud Force and Moment Coefficients
    Journal of Engineering for Gas Turbines and Power, 2010
    Co-Authors: Manoj K. Gupta, Dara W. Childs
    Abstract:

    An analysis is developed for a compressible bulk-flow model of the leakage path between a centrifugal-compressor Impeller’s shroud and its housing along the Impeller’s front and back sides. This development is an extension of analyses performed first by Childs (1989, ASME J. Vib. Acoust., Stress, Reliab. Des., 111, pp. 216–225) for pump Impellers. The bulk-flow model is used to predict reaction force and moment coefficients for the Impeller shroud. A labyrinth seal code developed by Childs and Scharrer ( 1986, ASME Trans. J. Eng. Gas Turbines Power, 108, pp. 325–331) is used to calculate the rotordynamic coefficients developed by the labyrinth seals in the compressor Stage and also provides a boundary condition for the shroud calculations. Comparisons between the measured shroud moment coefficients by Yoshida (1996, Proceedings of the 6th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery, 2, pp. 151–160) and model predictions show reasonable agreements for the clearance flow and reaction moments. For the conditions considered, low Mach number flow existed in the shroud clearance areas and compressible-flow and incompressible-flow models produced similar predictions. Childs’ model predictions for the direct damping and cross-coupled stiffness coefficients of a pump Impeller produced reasonable agreement; hence the present model was validated to the extent possible. A rotor model consisting of an overhung Impeller Stage supported by a nominally cantilevered rotor was analyzed for stability using the present bulk-flow model and an API standard Wachel–von Nimitz formula model (1981, J. Petrol. Technol., pp. 2252–2260). The bulk-flow model predicted significantly higher onset speeds of instability. Given that some compressors have been predicted to be comfortably stable using API standard Wachel–von Nimitz formula but have been unstable on the test stand, these results suggest that unidentified destabilizing forces and or moments are present in compressors. Seal rub conditions that arise from surge events and increase the seal clearances are simulated, showing that enlarged clearances increase the preswirl at the seals, thus increasing these seal’s destabilizing forces and reducing stability margins. These results are consistent with field experience. Predictions concerning the back shroud indicate that shunt-hole injection mainly acts to enhance stability by changing the flow field of the division wall or balance piston seals, not by influencing the back-shroud’s forces or moments. Effective swirl brakes at these seals also serve this purpose.

  • Rotordynamic Stability Predictions for Centrifugal Compressors Using a Bulk-Flow Model to Predict Impeller Shroud Force and Moment Coefficients
    Volume 5: Marine; Microturbines and Small Turbomachinery; Oil and Gas Applications; Structures and Dynamics Parts A and B, 2006
    Co-Authors: Manoj K. Gupta, Dara W. Childs
    Abstract:

    An analysis is developed for a compressible bulk-flow model of the leakage path between a centrifugal-compressor Impeller’s shroud and its housing along the Impeller’s front and back sides. This development is an extension of analyses performed first by Childs [15] for pump Impellers. The bulk-flow model is used to predict reaction force and moment coefficients for the Impeller shroud. A labyrinth seal code developed by Childs and Scharrer [21] is used to calculate the rotordynamic coefficients developed by the labyrinth seals in the compressor Stage and also provides a boundary condition for the shroud calculations. Comparisons between the measured shroud moment coefficients by Yoshida et al. [18] and model predictions show reasonable agreements for the clearance flow and reaction moments. For the conditions considered, low Mach number flow existed in the shroud clearance areas and compressible-flow and incompressible-flow models produced similar predictions. Childs’ model predictions for the direct damping and cross-coupled stiffness coefficients of a pump Impeller produced reasonable agreement; hence the present model was validated to the extent possible. A rotor model consisting of an overhung Impeller Stage supported by a nominally cantilevered rotor was analyzed for stability using the present bulk-flow model and an API standard Wachel-formula model [10]. The bulk-flow model predicted significantly higher onset speeds of instability. Given that some compressors have been predicted to be comfortably stable using API standard Wachel-formula but have been unstable on the test stand, these results suggest that unidentified destabilizing forces and or moments are present in compressors. Seal rub conditions that arise from surge events and increase the seal clearances are simulated, showing that enlarged clearances increase the preswirl at the seals, thus increasing these seal’s destabilizing forces and reducing stability margins. These results are consistent with field experience. Predictions concerning the back shroud indicate that shunt-hole injection mainly acts to enhance stability by changing the flow field of the division wall or balance piston seals, not by influencing the back-shroud’s forces or moments. Effective swirl brakes at these seals also serves this purpose.Copyright © 2006 by ASME

Rong Xie - One of the best experts on this subject based on the ideXlab platform.

  • Multidisciplinary analysis transient flow effects on the Impeller in a semi-open centrifugal Impeller Stage
    2017 IEEE 21st International Conference on Computer Supported Cooperative Work in Design (CSCWD), 2017
    Co-Authors: Rong Xie, M. Hao, L Guan, Y. Shi
    Abstract:

    Centrifugal compressors present very complex unsteady characteristics under running. The influence of unsteady aerodynamic load on blades surface may be related to the blade fracture. This issue involves aerodynamics, engineering thermodynamics, structural mechanics, computational fluid dynamics, mathematics, etc. A multidisciplinary analysis method based on CFD software has been applied to predict the flow field in a semi-open Impeller Stage of a centrifugal compressor, to analyze 3D flow characteristics in the transient flow field and aerodynamic load on the blade surfaces. Mechanism with a high amplitude frequency was focused on. Combined with entropy distribution diagrams, the wake vortex shedding frequency and the interference frequency generated by low-energy groups were captured. Results indicate that the wake vortex shedding and the low-energy groups are the main factors causing high aerodynamic load on the Impeller blade. The large pressure pulsation generated by wake vortex shedding and low-energy group may greatly threaten the blade safety. This study provides beneficial references for the analysis of blade fracture causes in a semi-open Impeller Stage of a centrifugal compressor.