Investigation of Efficient CFD Methods for Rotating Stall Prediction in a Centrifugal Compressor Stage

2014 ◽  
Author(s):  
Daniel DeMore ◽  
Elham Maghsoudi ◽  
Jorge Pacheco ◽  
James Sorokes ◽  
Brad Hutchinson ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Computational Study ◽  
Transformation Method ◽  
Rotating Stall ◽  
Computational Domain ◽  
Compressor Stage ◽  
Centrifugal Compressor Stage ◽  
Ansys Cfx ◽  
Minimum Number ◽  
Stall Cells

The Time Transformation Method in ANSYS CFX is investigated as an efficient substitution to Transient Rotor Stator (TRS) analysis for rotating stall prediction in a centrifugal compressor stage. The computational study was performed by varying the number of blade sectors to determine how the circumferential extent of the computational domain affects the accuracy of the stall prediction. The results obtained using a minimum number of blades, approximately one-quarter the full blade count, and approximately one-half the full blade count were compared to both TRS and steady simulations on the same mesh to characterize the predictive capability of each approach. It is shown that both steady and unsteady methods are able to predict the formation of stall cells, but significant qualitative and quantitative differences exist in the flowfield results. The largest mass flow rate at which rotating stall was captured and the number of stall cells were in good agreement with the experimental data.

scholarly journals DEVELOPMENT A MATHEMATICAL MODEL FOR RESEARCHING DYNAMIC PROCESSES IN THE LABYRINTH SEAL OF CENTRIFUGAL COMPRESSOR STAGE

2021 ◽  
pp. 115-124
Author(s):  
Anton Mikryukov ◽  
◽  
Vladimir Modorskii ◽  
Ivan Cherepanov ◽  
◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Labyrinth Seal ◽  
Operating Conditions ◽  
Dynamic Processes ◽  
Computational Domain ◽  
Compressor Stage ◽  
Centrifugal Compressor Stage ◽  
Interdisciplinary Approaches ◽  
Physical Features ◽  
Oscillatory Processes

Research of dynamic processes occurring under real operating conditions of centrifugal compressors often require the use of interdisciplinary approaches. This is determined by the character of the processes, which significantly affect each other during the compressor operation. However, when using interdisciplinary approaches, there are difficulties in the numerical implementation. They are associated with the need to take into account all the geometric and physical features of the processes under research, which leads to significant time and computational costs. At this article discusses issues related to the causes of oscillatory processes in the centrifugal compressor stage, in particular, in the labyrinth seal channel. In the article using 2FSI approach allowing to take into account the bilateral interaction of physical process on another. The article discusses issues related to the causes of oscillatory processes in the centrifugal compressor stage, in particular, in the labyrinth seal channel. The computational domain of research is presented, conceptual and mathematical statements are performed, which allow describing, among other things, self-oscillatory processes using the 2FSI approach.

Unsteady Flow in a Centrifugal Compressor Stage Equipped With a Vaned Diffuser and Cavities

2017 ◽  
Author(s):  
Mohand Younsi ◽  
Christophe Corneloup ◽  
François Moyroud ◽  
Antoine Baldacci
Keyword(s):  
Centrifugal Compressor ◽  
Transient Flow ◽  
Flow Behavior ◽  
Numerical Procedure ◽  
Transformation Method ◽  
Operating Conditions ◽  
Compressor Stage ◽  
Absolute Level ◽  
Impeller Blade ◽  
Centrifugal Compressor Stage

The purpose of this work is to present the Computational Fluid Dynamics (CFD) transient flow simulations of a centrifugal compressor stage with cavities. The cavities are included in the CFD model for several reasons. First the leakage flows and the windage effects are important to predict the absolute level performance of the stage (efficiency). Secondly the cavities also play an important role in the generation of the aerodynamic forcing on the impeller as well as in the prediction of the aerodynamic damping. As the compressor stage contains unequal numbers of blades and vanes, the Time Transformation method, an extension of the time inclining method is used in this work. This method which requires only a few passages per row is employed to reduce computational load and accurately model the full wheel. The numerical procedure is applied at design point firstly and then extended to the off-design operating conditions, permitting to compare and understand the transient flow behavior. The ability of the method to predict the impeller/diffuser interactions and cavity unsteady pressure response is discussed. The respective contributions of the diffuser, impeller blade passages and side cavities in terms of impeller forcing amplitude and frequency content are studied. In addition to this, comparisons between the experiment, the reduced model and the equivalent part wheel periodic solution are made to demonstrate the accuracy and computational efficiency of the considered transformation method.

scholarly journals Numerical Modeling of the Flow in a Vaneless Diffuser of Centrifugal Compressor Stage

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Mykola Kalinkevych ◽  
Oleg Shcherbakov
Keyword(s):  
Experimental Data ◽  
Numerical Modeling ◽  
Centrifugal Compressor ◽  
Compressor Stage ◽  
Vaneless Diffuser ◽  
Flow Core ◽  
Flow Area ◽  
Centrifugal Compressor Stage ◽  
Ansys Cfx ◽  
Sst Turbulence Model

This paper presents the results of numerical investigation of the flow in a vaneless diffuser of centrifugal compressor stage. Simulations were performed using both a commercial CFD package ANSYS CFX and the own-designed computer program. Steady conditions involving SST turbulence model were used for the calculations using CFX. To consider the interaction between impeller and diffuser, not just a diffuser but the whole stage was calculated. The own-designed methodology is based on solving of conservation equations with assumptions that flow in a diffuser is steady state and axisymmetric. The flow area is divided into the flow core and boundary layers. Results of calculation were compared with experimental data.

The Influence of a Diffuser Width on the Unsteady Performance of a Centrifugal Compressor Stage

2002 ◽  
Author(s):  
Abraham Engeda
Keyword(s):  
Centrifugal Compressor ◽  
Time Domain ◽  
Rotating Stall ◽  
Compressor Stage ◽  
Relative Speed ◽  
Vaneless Diffuser ◽  
Flow Rates ◽  
Centrifugal Compressor Stage ◽  
Different Types ◽  
Unsteady Performance

An experimental investigation was conducted to determine the effect of the vaneless diffuser width on the unsteady flow performance of a centrifugal compressor stage. Two compressor configurations with different vaneless diffuser width were investigated at four different impeller speeds and compared in the frequency and time domain. Only one diffuser rotating stall but different types of impeller rotating stalls were detected. The experiments show that the diffuser has a strong influence on the flow in the impeller including in areas way upstream. Analysis of the results indicated: • With increasing diffuser width the onset of impeller rotating stall was shifted to lower flow rates. • With increasing diffuser width the frequencies of the rotating stalls decreased. • There is a common tendency in most of the experiments to lower numbers of rotating cells with increasing relative speed. The impeller rotating stalls can be subdivided in a slow pattern with a relative speed to the impeller of 0.21 to 0.29 and a fast pattern with a relative speed of 0.50 to 0.56. This occurrence of two rotating pressure patterns confirms analytical results presented in previous investigations.

Effect of the Exit System on the Performance of a Low Specific Speed Industrial Centrifugal Compressor Stage

2003 ◽  
Author(s):  
Jean-Luc Di Liberti
Keyword(s):  
Centrifugal Compressor ◽  
High Frequency ◽  
Rotating Stall ◽  
Cfd Analysis ◽  
Compressor Stage ◽  
Test Results ◽  
Centrifugal Compressor Stage ◽  
Surge Margin ◽  
Low Specific Speed ◽  
Specific Speed

A low specific speed stage was tested with two different size volutes and a return vane system. The stage was instrumented with pressure probes at various locations, including the inlet and discharge flanges, diffuser inlet, diffuser exit, and return vane inlet. Cobra probes were positioned at the diffuser inlet and the return vane inlet for the return vane configuration to measure the flow angles. High frequency transducers were installed in the diffuser. This paper presents the test results showing the effect of two different volute sizes and of the return vane system on surge margin, rotating stall onset, and overall rotor and stage performance. Rotating stall criteria are reviewed, since this stage was previously tested with a different diffuser pinch. The performance is compared with some CFD analysis.

An Investigation of the Stability Enhancement of a Centrifugal Compressor Stage Using a Porous Throat Diffuser

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Lee Galloway ◽  
Stephen Spence ◽  
Sung In Kim ◽  
Daniel Rusch ◽  
Klemens Vogel ◽  
...  
Keyword(s):  
Centrifugal Compressor ◽  
Compressor Stage ◽  
Vaned Diffuser ◽  
Flow Rates ◽  
Stall Inception ◽  
Centrifugal Compressor Stage ◽  
Operating Range ◽  
Stable Operating ◽  
The Stability ◽  
Circumferential Pressure

The stable operating range of a centrifugal compressor stage of an engine turbocharger is limited at low mass flow rates by aerodynamic instabilities which can lead to the onset of rotating stall or surge. There have been many techniques employed to increase the stable operating range of centrifugal compressor stages. The literature demonstrates that there are various possibilities for adding special treatments to the nominal diffuser vane geometry, or including injection or bleed flows to modify the diffuser flow field in order to influence diffuser stability. One such treatment is the porous throat diffuser (PTD). Although the benefits of this technique have been proven in the existing literature, a comprehensive understanding of how this technique operates is not yet available. This paper uses experimental measurements from a high pressure ratio (PR) compressor stage to acquire a sound understanding of the flow features within the vaned diffuser which affect the stability of the overall compression system and investigate the stabilizing mechanism of the porous throat diffuser. The nonuniform circumferential pressure imposed by the asymmetric volute is experimentally and numerically examined to understand if this provides a preferential location for stall inception in the diffuser. The following hypothesis is confirmed: linking of the diffuser throats via the side cavity equalizes the diffuser throat pressure, thus creating a more homogeneous circumferential pressure distribution, which delays stall inception to lower flow rates. The results of the porous throat diffuser configuration are compared to a standard vaned diffuser compressor stage in terms of overall compressor performance parameters, circumferential pressure nonuniformity at various locations through the compressor stage and diffuser subcomponent analysis. The diffuser inlet region was found to be the element most influenced by the porous throat diffuser, and the stability limit is mainly governed by this element.

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