Effect of Suction Elbow and Inlet Guide Vanes on Flow Field in a Centrifugal Compressor Stage

2002 ◽  
Author(s):  
Michael M. Cui
Keyword(s):  
Flow Field ◽  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Power Laws ◽  
Working Fluid ◽  
Guide Vanes ◽  
Design And Optimization ◽  
Inlet Guide Vanes ◽  
Compressor Design ◽  
Overall Performance

Suction elbows and inlet guide vanes (IGVs) are typical upstream components in front of first-stage impellers in centrifugal compressors. The three-dimensional distortion induced by elbows and IGVs affects the flow field behind the IGV housing. Since the flow field in front of the impeller is subsonic, the flow motion induced by the rotating impeller will interact with the elbow and IGVs as well. The flow field resulting from these interactions is three-dimensional. The nature of this flow field defines design requirements of upstream components and impact overall performance of the compressor. To understand the mechanism controlling the interactions of up-steam components and optimize the compressor design for better efficiency and reliability, a numerical simulation of the flow field inside the entire first stage of the compressor was conducted. The stage studied includes suction elbow, IGV housing with vanes, and first-stage impeller. HFC 134a was used as the working fluid. The thermodynamic and transport properties of the refrigerant gas were modeled by the Martin-Hou equation of state and power laws respectively. The three-dimensional flow field was simulated with a Navier-Stokes solver using the k-ε turbulence model. The overall performance parameters are obtained by integrating the field quantities. The force, torque, and arm of moment acting on the IGVs were then calculated. The results can be used to improve centrifugal compressor design to achieve higher efficiency and improve reliability. The methodology developed in the current study can be applied to centrifugal compressor design and optimization.

Unsteady Flow Around Suction Elbow and Inlet Guide Vanes in a Centrifugal Compressor

2004 ◽  
Author(s):  
Michael M. Cui
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Centrifugal Compressor ◽  
Guide Vane ◽  
Power Laws ◽  
Working Fluid ◽  
Inlet Guide Vane ◽  
Guide Vanes ◽  
Inlet Guide Vanes ◽  
Compressor Design

A suction elbow and inlet guide vanes (IGVs) are typical upstream components in the front of the first-stage impeller in a centrifugal compressor. Since the flow field in the front of the impeller is subsonic, the flow motion induced by the rotating impeller interacts with the elbow and IGVs. These interactions induce turbulent unsteady flows inside compressors. The resulted unsteadiness affects efficiency, vibration, and noise generation of the compressor. To understand the mechanism controlling the interactions between up-steam components and to optimize the compressor design for better efficiency and reliability, the turbulent unsteady flow inside the first-stage of the compressor was simulated. The model includes the suction elbow, inlet guide vane housing, and first-stage impeller. HFC 134a was used as the working fluid. The thermodynamic and transport properties of the refrigerant gas were modeled by the Martin-Hou equation of state and power laws, respectively. The three-dimensional unsteady flow field was numerically simulated. The overall performance parameters were obtained by integrating the field quantities. The force, torque, and the arm of moments acting on the IGVs are then calculated. The results can be used to improve centrifugal compressor design to achieve higher efficiency and improve reliability.

scholarly journals Comparative Study of Unsteady Flows in a Transonic Centrifugal Compressor With Vaneless and Vaned Diffusers

2001 ◽  
Author(s):  
Michael M. Cui
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Power Laws ◽  
Working Fluid ◽  
Local Flow ◽  
Transonic Centrifugal Compressor ◽  
Compressor Performance ◽  
Overall Performance

To reduce vibration and noise level, the impeller and diffuser blade numbers inside an industrial compressor are typically chosen without common divisors. The shapes of volutes or collectors in these compressors are also not axis-symmetric. When impeller blades pass these asymmetric structures, the flow field in the compressor is time-dependent and three-dimensional. To obtain a fundamental physical understanding of these three-dimensional unsteady flow fields and assess their impact on the compressor performance, the flow field inside the compressors needs to be studied as a whole to include asymmetric and unsteady interaction between the compressor components. In current study, a unified three-dimensional numerical model was built for a transonic centrifugal compressor including impeller, diffusers, and volute. HFC 134a was used as the working fluid. The thermodynamic and transport properties of the refrigerant gas were modeled by the Martin-Hou equation of state and power laws, respectively. The three-dimensional unsteady flow field was simulated with a Navier-Stokes solver using the k-ε turbulent model. The overall performance parameters are obtained by integrating the field quantities. Both unsteady flow field and overall performance are analyzed comparatively for each component. The compressor was tested in a water chiller system instrumented to obtain both overall performance data and local flow field quantities. The experimental and numerical results agree well. The correlation between the overall compressor performance and local flow field quantities is defined. The methodology developed and data obtained in these studies can be applied to centrifugal compressor design and optimization.

Comparative Study of Vaneless and Vaned Diffusers in a Transonic Centrifugal Compressor With Real Gas

2000 ◽  
Author(s):  
Michael M. Cui
Keyword(s):  
Flow Field ◽  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Power Laws ◽  
Navier Stokes ◽  
Local Flow ◽  
Design And Optimization ◽  
Transonic Centrifugal Compressor ◽  
Overall Performance ◽  
The Impact

Vaneless and vaned diffusers in a transonic centrifugal compressor with the refrigerant HFC-134a were studied experimentally and numerically. The compressor was tested on a closed-loop stand instrumented to obtain both overall performance data and local flow field quantities. In numerical studies, the thermodynamic and transport properties of the refrigerant gas were modeled by the Martin-Hou equation of state and power laws, respectively. To include the interaction of the compressor components in these analyses, a unified three-dimensional numerical model was built for the complete compressor stage. The flow field was calculated with a Navier-Stokes solver using the k-ε turbulent model. The impact of the different diffusers on both local flow field and overall performance is analyzed comparatively for each component. The experimental and numerical results agree well. The correlation between the overall compressor performance and local flow field quantities is defined. The methodology developed and data obtained in these studies can be applied to centrifugal compressor design and optimization.

scholarly journals Comparative Study of Unsteady Flows in a Transonic Centrifugal Compressor with Vaneless and Vaned Diffusers

2005 ◽  
Vol 2005 (1) ◽  
pp. 90-103 ◽  
Author(s):  
Michael M. Cui
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Centrifugal Compressor ◽  
Three Dimensional ◽  
Power Laws ◽  
Working Fluid ◽  
Local Flow ◽  
Transonic Centrifugal Compressor ◽  
Compressor Performance ◽  
Overall Performance

To reduce vibration and noise level, the impeller and diffuser blade numbers inside an industrial compressor are typically chosen without common divisors. The shapes of volutes or collectors in these compressors are also not axis-symmetric. When impeller blades pass these asymmetric structures, the flow field in the compressor is time-dependent and three-dimensional. To obtain a fundamental physical understanding of these three-dimensional unsteady flow fields and assess their impact on the compressor performance, the flow field inside the compressors needs to be studied as a whole to include asymmetric and unsteady interaction between the compressor components. In the current study, a unified three-dimensional numerical model was built for a transonic centrifugal compressor including impeller, diffusers, and volute. HFC 134a was used as the working fluid. The thermodynamic and transport properties of the refrigerant gas were modeled by the Martin-Hou equation of state and power laws, respectively. The three-dimensional unsteady flow field was simulated with a Navier-Stokes solver using thek−εturbulent model. The overall performance parameters are obtained by integrating the field quantities. Both the unsteady flow field and the overall performance are analyzed comparatively for each component. The compressor was tested in a water chiller system instrumented to obtain both the overall performance data and local flow-field quantities. The experimental and numerical results agree well. The correlation between the overall compressor performance and local flow-field quantities is defined. The methodology developed and data obtained in these studies can be applied to the centrifugal compressor design and optimization.

Performance Characteristics of Two- and Three-Dimensional Impellers in Centrifugal Compressors

1988 ◽  
Vol 110 (1) ◽  
pp. 110-114 ◽  
Author(s):  
H. Harada
Keyword(s):  
Centrifugal Compressor ◽  
Closed Loop ◽  
Three Dimensional ◽  
Test Stand ◽  
Performance Characteristics ◽  
Working Fluid ◽  
Angle Distribution ◽  
Blade Angle ◽  
Operating Range ◽  
Overall Performance

The overall performance of two- and three-dimensional impellers of a centrifugal compressor were tested and compared. A closed-loop test stand with Freon gas as the working fluid was employed for the experiments. The inlet and outlet velocity distributions of all impellers were measured using three-hole cobra probes. As a result, it has been revealed that three-dimensional impeller in terms of efficiency, head coefficient, and operating range. Further, it has also been clarified that the impeller slip factor is affected by blade angle distribution.

A New Gas Compressor Product Development

1996 ◽  
Author(s):  
Ronald P. Porter
Keyword(s):  
Product Development ◽  
Centrifugal Compressor ◽  
High Efficiency ◽  
Low Cost ◽  
Design Features ◽  
Guide Vanes ◽  
Inlet Guide Vanes ◽  
Compressor Design ◽  
Gas Seals ◽  
Product Definition

A high efficiency, low cost gas compressor is under development. Design has been completed and fabrication is in process. The manufacturer’s background in centrifugal compressor design and current methodology is discussed along with product definition. Assembly and test of the first unit is planned for summer 1996. The design features a single-stage overhung centrifugal compressor, variable inlet guide vanes, and dry gas seals.

scholarly journals Performance Characteristics of Two- and Three-Dimensional Impellers in Centrifugal Compressors

1986 ◽  
Author(s):  
H. Harada
Keyword(s):  
Centrifugal Compressor ◽  
Closed Loop ◽  
Three Dimensional ◽  
Performance Characteristics ◽  
Working Fluid ◽  
Angle Distribution ◽  
Two Dimensional ◽  
Blade Angle ◽  
Operating Range ◽  
Overall Performance

The overall performance of two- and three-dimensional impellers of a centrifugal compressor were tested and compared. A closed loop test stand with Freon gas as working fluid was employed for the experiments. The inlet and outlet velocity distribtions of all impellers were measured using three hole cobra probes. As a result, it has been revealed that three-dimensional impellers are superior to two-dimensional one in terms of efficiency, head coefficient and operating range. Further, it has also been clarified that the impeller slip factor is affected by blade angle distribution.

Use of Inlet Guide Vanes for a Miniature Centrifugal Compressor

2005 ◽  
Author(s):  
Xiaoyi Li ◽  
Lei Zhou ◽  
Jay Kapat ◽  
Louis C. Chow
Keyword(s):  
Centrifugal Compressor ◽  
Total Pressure ◽  
High Speed ◽  
Cooling System ◽  
Pressure Ratio ◽  
Working Fluid ◽  
Guide Vanes ◽  
Inlet Guide Vanes ◽  
Total Pressure Ratio ◽  
Isentropic Efficiency

A novel design for a high-speed, miniature centrifugal compressor for a miniature RTBC (reverse turbo Brayton cycle) cryogenic cooling system is the focus of this paper. Due to the geometrical restriction imposed by the cryocooling system, the outer radius of the compressor is limited to 2.5 cm. Such a small compressor must rotate at a high speed in order to provide an acceptable pressure ratio. Miniature design precludes the use of inducers with large angles. In order to compensate for the absence of conventional inducers, the proposed design uses inlet guide vanes (IGV) that produce preswirl at the impeller inlet. IGV is followed by a radial impeller and an axial diffuser. The design speed for this compressor is 313,000 rpm for an overall static-to-total pressure ratio of 1.7 with helium as the working fluid for the compressor and the cryocooling system. The analysis undertaken in this paper is for an aerodynamically similar design with air as the working fluid. The rotational speed is 108,000 rpm and the overall static-to-total pressure ratio of 1.55. This paper concentrates on computational prediction of the performance of the compressor. The three-dimensional transient simulation is performed by using sliding mesh model (SMM). Blade tip leakage is not considered in the computation presented here. The unsteady solution predicts the interaction between IGV and the impeller, and between the impeller and the diffuser. The isentropic efficiency of impeller is found to be 81% at the design point. Based on the results obtained in this study, the inlet angle of diffuser vanes is modified to match the gas flow at the impeller exit, resulting in an increase of the isentropic efficiency of diffuser from 8.6% to 74.8%. It is also found that the performance of upstream components — IGV and impeller, are not affected by the performance of the diffuser.

Efficiency Improvement at Part Load of Multistage Centrifugal Compressor for Turbo Chiller

2011 ◽  
Author(s):  
Daisuke Kawaguchi ◽  
Takeshi Okada ◽  
Yasushi Nakamura ◽  
Masatoshi Terasaki
Keyword(s):  
Centrifugal Compressor ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Efficiency Improvement ◽  
Guide Vanes ◽  
Part Load ◽  
Inlet Guide Vanes ◽  
Opening Ratio ◽  
The One ◽  
Multistage Centrifugal Compressor

The effect of variable inlet guide vanes in the multistage centrifugal compressor for the turbo chiller on the part load efficiency improvement was analyzed by using CFD (computational fluid dynamics). The area we analyzed targeted two stages including the first and second variable inlet guide vanes arranged upstream of each compressor. The numerical simulation involved three-dimensional, steady, and compressible flow analysis with ANSYS-CFX. The flash gas injected from the intermediate inlet of the economizer passage was taken into account. The part-load efficiency was measured while changing the opening ratio for the first and second variable inlet guide vanes. The predicted part-load efficiency corresponded to the one that was measured. The predicted flow pattern indicated that higher efficiency could be obtained by adjusting the opening ratio for the first and second variable inlet guide vanes to suppress excessive prewhirl from the first impeller and stall from the second impeller.

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