3D Viscous Inverse Design of Vaned Diffuser to Suppress Flow Unsteadiness in a Centrifugal Compressor

2005 ◽  
Author(s):  
Victor I. Mileshin ◽  
Igor A. Brailko ◽  
Andrew N. Startsev ◽  
Igor K. Orekhov
Keyword(s):  
Centrifugal Compressor ◽  
Stokes Equations ◽  
Reverse Flow ◽  
Pressure Ratio ◽  
Design Procedure ◽  
Inverse Design ◽  
Navier Stokes ◽  
Low Velocity ◽  
Vaned Diffuser ◽  
Pressure Surface

Present paper is devoted to numerical investigation of unsteadiness caused by impeller-diffuser interaction in a 8:1 total pressure ratio centrifugal compressor. The compressor designed by CIAM [7], and manufactured and tested by Customer gave satisfactory performances even under the first test. Further development requires new insights and advanced numerical tools. In this context, this paper presents Navier-Stokes computations of 3D viscous unsteady flow field within the impeller-diffuser configuration. Steady and unsteady computations indicated spacious zone of low velocity / reverse flow on pressure surface of the diffuser vane. To suppress this reverse flow, new vaned diffuser has been tailored through application of 3D inverse design procedure for Navier-Stokes equations [8]. Subsequent steady and unsteady N-S calculations performed for compressor with the new diffuser demonstrated depression of reverse flow within diffuser and different unsteady loading of the diffuser vane.

1995 ASME Gas Turbine Award Paper: Development and Application of a Multistage Navier–Stokes Solver: Part I—Multistage Modeling Using Bodyforces and Deterministic Stresses

1998 ◽  
Vol 120 (2) ◽  
pp. 205-214 ◽  
Author(s):  
C. M. Rhie ◽  
A. J. Gleixner ◽  
D. A. Spear ◽  
C. J. Fischberg ◽  
R. M. Zacharias
Keyword(s):  
Stokes Equations ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Design Procedure ◽  
Potential Interaction ◽  
Theoretical Development ◽  
Navier Stokes ◽  
Radial Profiles ◽  
Compressor Performance ◽  
High Level

A multistage compressor performance analysis method based on the three-dimensional Reynolds-averaged Navier-Stokes equations is presented in this paper. This method is an average passage approach where deterministic stresses are used to ensure continuous physical properties across interface planes. The average unsteady effects due to neighboring blades and/or vanes are approximated using deterministic stresses along with the application of bodyforces. Bodyforces are used to account for the “potential” interaction between closely coupled (staged) rows. Deterministic stresses account for the “average” wake blockage and mixing effects both axially and radially. The attempt here is to implement an approximate technique for incorporating periodic unsteady flow physics that provides for a robust multistage design procedure incorporating reasonable computational efficiency. The present paper gives the theoretical development of the stress/bodyforce models incorporated in the code, and demonstrates the usefulness of these models in practical compressor applications. Compressor performance prediction capability is then established through a rigorous code/model validation effort using the power of networked workstations. The numerical results are compared with experimental data in terms of one-dimensional performance parameters such as total pressure ratio and circumferentially averaged radial profiles deemed critical to compressor design. This methodology allows the designer to design from hub to tip with a high level of confidence in the procedure.

Numerical Simulations of Onset of Volute Stall Inside a Centrifugal Compressor

2008 ◽  
Author(s):  
Hua Chen ◽  
Strong Guo ◽  
Xiao-Cheng Zhu ◽  
Zhao-Hui Du ◽  
Stone Zhao
Keyword(s):  
Centrifugal Compressor ◽  
Peak Pressure ◽  
Stokes Equations ◽  
Pressure Ratio ◽  
Pressure Rise ◽  
Navier Stokes ◽  
Cross Sectional ◽  
Navier Stokes Equations ◽  
Mass Flow Rates ◽  
Discharge Section

In a previous publication (Guo & Chen et al., 2007), the authors solved the unsteady, 3-D Navier-Stokes equations with the k-ε turbulence model using CFX software to show that there is a volute stall coincided with the stage stall of a turbocharger centrifugal compressor operated at 423m/s tip speed and the stage stall frequency is dictated by a volute standing wave. This paper presents the flow condition at the vaneless diffuser and volute from the same simulation at various mass flow rates from stage peak efficiency to deep stage stall. Time averaged flow conditions show that (1) the influence of exducer blade passing at the volute inlet rapidly diminishes at the compressor peak pressure ratio point and the influence vanishes when the stage is in stall; (2) only at the peak pressure ratio point, circumferentially averaged, spanwise distribution of radial velocity at the volute inlet has an inflection point and the distribution meets the requirement of the Fjo̸rtoft instability theorem; (3) in the volute discharge section, the flow stalls after the stage stalls and the vortex core at the cross sectional center of the section breaks down; (4) impeller total pressure rise curve has a flat region in the middle before the stage stalls and (5) diffuser stall triggers the stage stall and drives the volute into stall.

A Numerical Study on Performances of Centrifugal Compressor Stages With Different Radial Gaps

2000 ◽  
Author(s):  
K. Sato ◽  
L. He
Keyword(s):  
Centrifugal Compressor ◽  
Stokes Equations ◽  
Numerical Study ◽  
Axial Compressor ◽  
Navier Stokes ◽  
Centrifugal Impeller ◽  
Vaned Diffuser ◽  
Navier Stokes Equations ◽  
Performance Predictions ◽  
Radial Gap

A numerical study of 3D unsteady flows in centrifugal compressor stages solving the Navier-Stokes equations is presented. The emphasis is on the effect of the radial gap between blade rows on the aerodynamic performance. In the numerical tests, Krain’s centrifugal impeller was combined with a DCA (Double Circular Arc) type radial vaned diffuser. The compressor stages with three settings of radial gap ranging from 5 to 15 percent of the impeller trailing edge radius are configured and unsteady flow simulations are carried out to compare the time-averaged efficiencies. The performance predictions show that the efficiency is deteriorated if the radial gap between blade rows is reduced with intensified blade row interaction, which is in contradiction to the general trend for axial compressor stages. In the centrifugal compressors tested, wake chopping by diffuser vanes, which usually benefits efficiency in axial compressor stages, causes unfavourable wake compression through the diffuser passages to deteriorate the efficiency.

Design and Experimental Study on the Surge Performance Improvement by the Effects of Bleed Slot Casing of a Centrifugal Compressor

2014 ◽  
Author(s):  
Hong Won Kim ◽  
Jae Hoon Chung ◽  
Hyo Seong Lee ◽  
Min Ouk Choi
Keyword(s):  
Centrifugal Compressor ◽  
Stokes Equations ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Design Parameters ◽  
Navier Stokes Equations ◽  
Operating Range ◽  
Surge Margin ◽  
Commercial Code

The primary design goal of a compressor is focused on improving efficiency. Secondary objective is to widen the compressor’s operating range. This paper presents a numerical and experimental investigation of the influence of the bleed slot to enlarge operating range for the 1.2MW class centrifugal compressor installed in a turbocharger. The main design parameters of the bleed slot casing are upstream slot position, inlet pipe slope, downstream slot position and width. The DOE (design of experiment) method was carried out to optimize the casing design. Numerical analyses were done by the commercial code ANSYS-CFX based on the three dimensional Reynolds-averaged Navier-Stokes equations. From the analysis, as the downstream slot position and width are smaller and upstream position is located away from impeller inlet, efficiency and pressure ratio are increased. Experimental works were done with and without the bleed slot casing. The simulation results were in good agreement with the test data. In case without the bleed slot casing, the surge margin value came out to be only 11.8% but with the optimized bleed slot design, the surge margin reached 23%. Therefore, the surge margin increase of 11.2% was achieved.

Development and Application of a Multistage Navier-Stokes Solver: Part I — Multistage Modeling Using Bodyforces and Deterministic Stresses

1995 ◽  
Author(s):  
Chae M. Rhie ◽  
Aaron J. Gleixner ◽  
David A. Spear ◽  
Craig J. Fischberg ◽  
Robert M. Zacharias
Keyword(s):  
Stokes Equations ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Design Procedure ◽  
Potential Interaction ◽  
Theoretical Development ◽  
Navier Stokes ◽  
Interface Plane ◽  
Radial Profiles ◽  
Compressor Performance

A novel multistage compressor performance analysis method based on the three-dimensional Reynolds averaged Navier-Stokes equations is presented in this paper. This approach is a “continuous interface plane approach” where deterministic stresses are used to ensure continuous physical properties across interface planes. The average unsteady effects due to neighboring blades and/or vanes are approximated using deterministic stresses along with the application of bodyforces. Bodyforces are used to account for the “potential” interaction between closely coupled (staged) rows. Deterministic stresses account for the “average” wake blockage and mixing effects both axially and radially. The attempt here is to implement an approximate technique for incorporating periodic unsteady flow physics that provides for a robust multistage design procedure incorporating reasonable computational efficiency. The present paper gives the theoretical development of the stress/bodyforce models incorporated in the code, and demonstrates the usefulness of these models in practical compressor applications. Compressor performance prediction capability is then established through a rigorous code/model validation effort using the power of networked workstations. The numerical results are compared with experimental data in terms of one-dimensional performance parameters such as total pressure ratio and circumferentially averaged radial profiles deemed critical to compressor design. This methodology allows the designer to design from hub to tip with a high level of confidence in the procedure.

Inverse Design of and Experimental Measurements in a Double-Passage Transonic Turbine Cascade Model

2005 ◽  
Vol 127 (3) ◽  
pp. 619-626 ◽  
Author(s):  
G. M. Laskowski ◽  
A. Vicharelli ◽  
G. Medic ◽  
C. J. Elkins ◽  
J. K. Eaton ◽  
...  
Keyword(s):  
Stokes Equations ◽  
Design Procedure ◽  
Cascade Model ◽  
Inverse Design ◽  
Navier Stokes ◽  
Turbine Cascade ◽  
Flow Conditions ◽  
Navier Stokes Equations ◽  
Attached Flow ◽  
Transonic Turbine

A new transonic turbine cascade model that accurately produces infinite cascade flow conditions with minimal compressor requirements is presented. An inverse design procedure using the Favre-averaged Navier-Stokes equations and k‐ε turbulence model based on the method of steepest descent was applied to a geometry consisting of a single turbine blade in a passage. For a fixed blade geometry, the passage walls were designed such that the surface isentropic Mach number (SIMN) distribution on the blade in the passage matched the SIMN distribution on the blade in an infinite cascade, while maintaining attached flow along both passage walls. An experimental rig was built that produces realistic flow conditions, and also provides the extensive optical access needed to obtain detailed particle image velocimetry measurements around the blade. Excellent agreement was achieved between computational fluid dynamics (CFD) of the infinite cascade SIMN, CFD of the designed double passage SIMN, and the measured SIMN.

Numerical Evaluation of the Unsteady Flow in a Centrifugal Compressor With Vaned Diffuser via URANS Approach

2016 ◽  
Author(s):  
Ali Zamiri ◽  
Byung Ju Lee ◽  
Jin Taek Chung
Keyword(s):  
Centrifugal Compressor ◽  
Stokes Equations ◽  
Pressure Ratio ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Frequency Noise ◽  
Computational Domain ◽  
Vaned Diffuser ◽  
Noise Characteristics ◽  
Time Space

The three dimensional, compressible, unsteady Navier-Stokes equations are solved to investigate the flow field of a centrifugal compressor with high compression ratio. Computational domain is consisted of an inlet bell and impeller with splitter blades followed by a two dimensional wedge vaned diffuser. The numerical method is validated by comparing the computational results with the experiments in terms of pressure ratio and compressor efficiency. The present study focuses on the unsteady pressure fluctuations and entropy production within the impeller and diffuser passages at the compressor design point. It is shown that the interaction between the impeller and diffuser blades leads to unsteadiness at the interface region and a pulsating behavior within the diffuser passages. Pressure waves with different convective velocities, generated by the impeller-diffuser interaction and pseudo-periodic unsteady separation bubbles, are captured in time/space domain along the diffuser blade surfaces. The pressure fluctuation spectra captured at the impeller-diffuser interface is evaluated to analyze the noise characteristics of the centrifugal compressor as a main source of blade passing frequency noise.

Numerical Investigation of a Transonic Centrifugal Compressor

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Michele Marconcini ◽  
Filippo Rubechini ◽  
Andrea Arnone ◽  
Seiichi Ibaraki
Keyword(s):  
Shock Waves ◽  
Flow Field ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Turbulence Models ◽  
Tip Clearance ◽  
Complex Flow ◽  
Low Velocity ◽  
Flow Measurements ◽  
Vaned Diffuser

A three-dimensional Navier-Stokes solver is used to investigate the flow field of a high-pressure ratio centrifugal compressor for turbocharger applications. Such a compressor consists of a double-splitter impeller followed by a vaned diffuser. The inlet flow to the open shrouded impeller is transonic, thus giving rise to interactions between shock waves and boundary layers and between shock waves and tip leakage vortices. These interactions generate complex flow structures which are convected and distorted through the impeller blades. Detailed laser Doppler velocimetry flow measurements are available at various cross sections inside the impeller blades highlighting the presence of low-velocity flow regions near the shroud. Particular attention is focused on understanding the physical mechanisms which govern the flow phenomena in the near shroud region. To this end numerical investigations are performed using different tip clearance modelizations and various turbulence models, and their impact on the computed flow field is discussed.

Aerodynamic Performances of a Centrifugal Compressor With Discrete Cavities

2017 ◽  
Author(s):  
Sang-Bum Ma ◽  
Kwang-Yong Kim
Keyword(s):  
Centrifugal Compressor ◽  
Stokes Equations ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Stall Margin ◽  
Tetrahedral Grid ◽  
Aerodynamic Performances ◽  
Inclined Angle

In this study, aerodynamic performance of the centrifugal compressor was investigated by using a recirculating device called discrete cavities. A parametric study was conducted using six parameters related to the geometry of the discrete cavities, i.e., the inclined angle, the port angle and width, the length of cavity, the axial location of each cavity, and the number of cavities. Three-dimensional Reynolds-averaged Navier-Stokes equations with shear stress transport turbulence model were used for aerodynamic analysis of the centrifugal compressor with discrete cavities. The hexahedral grid was used in impeller domain and tetrahedral grid was used in volute and inclined discrete cavities. The numerical results for the adiabatic efficiency and the total pressure ratio (inlet to outlet) showed good agreements with experimental data. It was found that inclination of the discrete cavities further increased the stall margin without loss of efficiency compared to the uninclined discrete cavities.

Numerical Analysis of the Vaned Diffuser of a Transonic Centrifugal Compressor

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Michele Marconcini ◽  
Filippo Rubechini ◽  
Andrea Arnone ◽  
Seiichi Ibaraki
Keyword(s):  
Flow Field ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Flow Measurements ◽  
Vaned Diffuser ◽  
High Pressure Ratio ◽  
Unsteady Interaction ◽  
Inlet Conditions

A three-dimensional Navier–Stokes solver is used to investigate the flow field of a high pressure ratio centrifugal compressor for turbocharger applications. Such a compressor consists of a double-splitter impeller followed by a vaned diffuser. Particular attention is focused on the analysis of the vaned diffuser, designed for high subsonic inlet conditions. The diffuser is characterized by a complex three-dimensional flow field and influenced by the unsteady interaction with the impeller. Detailed particle image velocimetry flow measurements within the diffuser are available for comparison purposes.

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