Characterizing Flow Effects of Ported Shroud Casing Treatment on Centrifugal Compressor Performance

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
George A. Christou ◽  
Choon S. Tan ◽  
Borislav T. Sirakov ◽  
Vai-Man Lei ◽  
Giuseppe Alescio
Keyword(s):  
Mass Flow ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Flow Path ◽  
Main Flow ◽  
Tip Leakage Flow ◽  
Casing Treatment ◽  
Compressor Performance ◽  
Flow Effects ◽  
Ported Shroud

This paper presents an investigation of the effects of ported shroud (PS) self-recirculating casing treatment used in turbocharger centrifugal compressors for increasing the operable range. The investigation consists of computing three-dimensional flow in a representative centrifugal compressor with and without PS at various levels of approximations in flow physics and geometrical configuration; this provides an enabler for establishing the causal link between PS flow effects and compressor performance changes. It is shown that the main flow path perceives the PS flow as a combination of flow actuations that include injection and removal of mass flow and injection of axial momentum and tangential momentum. A computational model in which the presence of the PS is replaced by imposed boundary conditions (BCs) that reflect the individual flow actuations has thus been formulated and implemented. The removal of a fraction of the inducer mass flow has been determined to be the dominant flow actuation in setting the performance of PS compressors. Mass flow removal reduces the flow blockage associated with the impeller tip leakage flow and increases the diffusion in the main flow path. Adding swirl to the injected flow in the direction opposite to the wheel rotation results in an increase of the stagnation pressure ratio and a decrease of the efficiency. The loss generation in the flow path has been defined to rationalize efficiency changes associated with PS compressor operation.

Characterizing Flow Effects of Ported Shroud Casing Treatment on Centrifugal Compressor Performance

2016 ◽  
Author(s):  
George A. Christou ◽  
Choon S. Tan ◽  
Borislav T. Sirakov ◽  
Vai-Man Lei ◽  
Giuseppe Alescio
Keyword(s):  
Mass Flow ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Flow Path ◽  
Main Flow ◽  
Tip Leakage Flow ◽  
Casing Treatment ◽  
Compressor Performance ◽  
Flow Effects ◽  
Ported Shroud

This paper presents an investigation of the effects of Ported Shroud (PS) self-recirculating casing treatment used in turbocharger centrifugal compressors for increasing the operable range. The investigation consists of computing three-dimensional flow in a representative centrifugal compressor with and without PS at various levels of approximations in flow physics and geometrical configuration; this provides an enabler for establishing the causal link between PS flow effects and compressor performance changes. It is shown that the main flow path perceives the PS flow as a combination of flow actuations that include injection and removal of mass flow, and injection of axial momentum and tangential momentum. A computational model in which the presence of the PS is replaced by imposed boundary conditions that reflect the individual flow actuations has thus been formulated and implemented. The removal of a fraction of the inducer mass flow has been determined to be the dominant flow actuation in setting the performance of PS compressors. Mass flow removal reduces the flow blockage associated with the impeller tip leakage flow and increases the diffusion in the main flow path. Adding swirl to the injected flow in the direction opposite to the wheel rotation results in an increase of the stagnation pressure ratio and a decrease of the efficiency. The loss generation in the flow path has been defined to rationalize efficiency changes associated with PS compressor operation.

Centrifugal Compressor Performance Prediction Using Gaussian Process Regression and Artificial Neural Networks

2019 ◽  
Author(s):  
Pau Cutrina Vilalta ◽  
Hui Wan ◽  
Soumya S. Patnaik
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Rotational Speed ◽  
Data Augmentation ◽  
Pressure Ratio ◽  
Gaussian Process Regression ◽  
Compressor Performance ◽  
Artificial Neural

Abstract In this paper, we use various regression models and Artificial Neural Network (ANN) to predict the centrifugal compressor performance map. Particularly, we study the accuracy and efficiency of Gaussian Process Regression (GPR) and Artificial Neural Networks in modelling the pressure ratio, given the mass flow rate and rotational speed of a centrifugal compressor. Preliminary results show that both GPR and ANN can predict the compressor performance map well, for both interpolation and extrapolation. We also study the data augmentation and data minimzation effects using the GPR. Due to the inherent pressure ratio data distribution in mass-flow-rate and rotational-speed space, data augmentation in the rotational speed is more effective to improve the ANN performance than the mass flow rate data augmentation.

Stability Improvement of High-Pressure-Ratio Turbocharger Centrifugal Compressor by Asymmetric Flow Control: Part II—Non-Axisymmetric Self Recirculation Casing Treatment

2010 ◽  
Author(s):  
Xinqian Zheng ◽  
Yangjun Zhang ◽  
Mingyang Yang ◽  
Takahiro Bamba ◽  
Hideaki Tamaki
Keyword(s):  
High Pressure ◽  
Flow Control ◽  
Centrifugal Compressor ◽  
Control Method ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Asymmetric Flow ◽  
Casing Treatment ◽  
High Pressure Ratio ◽  
Compressor Performance

This is the Part II of a two-part paper involving the development of asymmetric flow control method to widen the operating range of a turbocharger centrifugal compressor with high-pressure-ratio. Non-axisymmetric Self Recirculation Casing Treatment (SRCT) as an instance of asymmetric flow control method is presented. Experimental and numerical methods were used to investigate the impact of non-axisymmetric SRCT on surge point of the centrifugal compressor. Firstly, the influence of the geometry of a symmetric SRCT on the compressor performance was studied by means of numerical simulation. The key parameter of the SRCT was found to be the distance from the main blade leading edge to the rear groove (Sr). Next, several arrangements of a non-axisymmetric SRCT were designed, based on flow analysis presented in Part I. Then, a series of experiments was carried out to analyze the influence of non-axisymmetric SRCT on the compressor performance. Results show that the non-axisymmetry SRCT has certain influence on performance and has a larger potential for stability improvement than the traditional symmetric SRCT. For the investigated SRCT, the surge flow rate of the compressor with the non-axisymmetric SRCT is about 10% lower than that of the compressor with symmetric SRCT. The largest surge margin (smallest surge flow rate) can be obtained when the phase of the largest Sr is coincident with the phase of the minimum static pressure in the vicinity of the leading edge of the splitter blades.

scholarly journals Stability Improvement of High-Pressure-Ratio Turbocharger Centrifugal Compressor by Asymmetrical Flow Control—Part II: Nonaxisymmetrical Self-Recirculation Casing Treatment

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Xinqian Zheng ◽  
Yangjun Zhang ◽  
Mingyang Yang ◽  
Takahiro Bamba ◽  
Hideaki Tamaki
Keyword(s):  
High Pressure ◽  
Flow Control ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Control Method ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Casing Treatment ◽  
High Pressure Ratio ◽  
Compressor Performance

This is part II of a two-part paper involving the development of an asymmetrical flow control method to widen the operating range of a turbocharger centrifugal compressor with high-pressure ratio. A nonaxisymmetrical self-recirculation casing treatment (SRCT) as an instance of asymmetrical flow control method is presented. Experimental and numerical methods were used to investigate the impact of nonaxisymmetrical SRCT on the surge point of the centrifugal compressor. First, the influence of the geometry of a symmetric SRCT on the compressor performance was studied by means of numerical simulation. The key parameter of the SRCT was found to be the distance from the main blade leading edge to the rear groove (Sr). Next, several arrangements of a nonaxisymmetrical SRCT were designed, based on flow analysis presented in part I. Then, a series of experiments were carried out to analyze the influence of nonaxisymmetrical SRCT on the compressor performance. Results show that the nonaxisymmetrical SRCT has a certain influence on the performance and has a larger potential for stability improvement than the traditional symmetric SRCT. For the investigated SRCT, the surge flow rate of the compressor with the nonaxisymmetrical SRCTs is about 10% lower than that of the compressor with symmetric SRCT. The largest surge margin (smallest surge flow rate) can be obtained when the phase of the largest Sr is coincident with the phase of the minimum static pressure in the vicinity of the leading edge of the splitter blades.

An Investigation of Centrifugal Compressor Stability Enhancement Using a Novel Vaned Diffuser Recirculation Technique

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Lee Galloway ◽  
Daniel Rusch ◽  
Stephen Spence ◽  
Klemens Vogel ◽  
René Hunziker ◽  
...  
Keyword(s):  
Mass Flow ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Vaned Diffuser ◽  
Casing Treatment ◽  
Operating Range ◽  
Stable Operating ◽  
Mass Flow Rates ◽  
Low Mass ◽  
Casing Treatments

The main centrifugal compressor performance criteria are pressure ratio, efficiency, and wide flow range. The relative importance of these criteria, and therefore the optimum design balance, varies between different applications. Vaned diffusers are generally used for high-performance applications as they can achieve higher efficiencies and pressure ratios, but have a reduced operating range, in comparison to vaneless diffusers. Many impeller-based casing treatments have been developed to enlarge the operating range of centrifugal compressors over the last decades but there is much less information available in open literature for diffuser focused methods, and they are not widely adopted in commercial compressor stages. The development of aerodynamic instabilities at low mass flow rate operating conditions can lead to the onset of rotating stall or surge, limiting the stable operating range of the centrifugal compressor stage. More understanding of these aerodynamic instabilities has been established in recent years. Based on this additional knowledge, new casing treatments can be developed to prevent or suppress the development of these instabilities, thus increasing the compressor stability at low mass flow rates. This paper presents a novel vaned diffuser casing treatment that successfully increased the stable operating range at low mass flow rates and high pressure ratios. Detailed experimental measurements from a high pressure ratio turbocharger compressor stage combined with complementary CFD simulations were used to examine the effect of the new diffuser casing treatment on the compressor flow field and led to the improvement in overall compressor stability. A detailed description of how the new casing treatment operates is presented within the paper.

Casing Treatment for Desensitization of Compressor Performance and Stability to Tip Clearance

2016 ◽  
Vol 138 (12) ◽  
Author(s):  
Mert Cevik ◽  
Huu Duc Vo ◽  
Hong Yu
Keyword(s):  
Pressure Ratio ◽  
Tip Clearance ◽  
Design Strategies ◽  
Tip Leakage Flow ◽  
Cfd Simulations ◽  
Stall Margin ◽  
Casing Treatment ◽  
Tip Leakage ◽  
Compressor Performance ◽  
Nominal Performance

This paper presents the development of a novel casing treatment to reduce compressor performance and stall margin sensitivities to tip clearance increase. A linked research project on blade design strategies for desensitization had discovered two flow features that reduce sensitivity to tip clearance, namely increased incoming meridional momentum in the rotor tip region and reduction/elimination of double tip leakage flow. Double tip leakage flow is the flow that exits one tip clearance and enters the tip clearance of the circumferentially adjacent blade instead of convecting downstream out of the blade passage. A new and practical casing treatment was developed and analyzed through Reynolds-averaged Navier–Stokes (RANS) computational fluid dynamics (CFD) simulations to decrease double tip leakage and reduce or even eliminate performance and stall margin sensitivity to tip clearance size. The casing treatment design consists of sawtooth-shaped circumferential indentations placed on the shroud over the rotor with a depth on the order of the tip clearance size. A detailed analysis of the flow field allowed for the elucidation of the flow mechanism associated with this casing treatment. A computational parametric study gave preliminary design rules for minimizing both performance/stall margin sensitivity to tip clearance and nominal performance loss. An improved casing indentation design was produced for which CFD simulations showed a complete desensitization of pressure ratio and stall margin while reducing efficiency sensitivity significantly for the tip clearance range studied with only a very small penalty in nominal pressure ratio. Further simulations showed that this casing treatment can be combined with desensitizing blade design strategies to further reduce tip sensitivity and reduce/eliminate/reverse nominal performance penalty. Lastly, preliminary CFD simulations on an axial compressor stage indicate that this shallow indentations' casing treatment strategy remains effective in a stage environment.

Casing Treatment of Centrifugal Compressors

2015 ◽  
Author(s):  
Jisha Noushad ◽  
Anand Babu Dhamarla ◽  
Pavan Kumar
Keyword(s):  
Mass Flow ◽  
Centrifugal Compressor ◽  
Reverse Flow ◽  
Pressure Fluctuations ◽  
Centrifugal Compressors ◽  
Flow Rates ◽  
Casing Treatment ◽  
Operating Range ◽  
Mass Flow Rates ◽  
Ported Shroud

The operating range of any compressor is controlled by Surge and Choke. Surge occurs at lower mass flow rates with large pressure fluctuations and flow reversals, while choke occurs at higher mass flow rates when the flow rate reaches the limit which compressor can discharge. Ported shroud is a cost effective casing treatment that can greatly improve operating range of centrifugal compressors. By removing the stagnant and reverse flow from shroud wall boundary-layer region and recirculating it to impeller inlet, it has been demonstrated that larger range of operability can be achieved without much loss on compressor efficiency. This paper demonstrates the improvement of a centrifugal compressor operational range with ported shroud configuration. A series of CFD simulations were carried out with open source centrifugal compressor geometry (NASA HPCC 4:1) to create performance characteristics/speed-lines. The CFD methodology and practices were validated by comparing the results with the experimental data. Performance evaluation of ported shroud configuration is done with respect to solid shroud. Ported shroud compressor is proven to give higher choke mass flow and also a better surge margin compared to the Solid shroud model. The phenomena of in-flowing and out-flowing port have also been demonstrated. Emphasis was given to understand how ported shroud helps to achieve a better performance. A design optimization study has also been carried out in order to establish the optimum ported shroud configuration. Design parameter such as port location has been selected and the effect of this parameter on the performance of the compressor is studied using CFD. Optimum port geometry was proposed.

scholarly journals Stall Margin Improvement in a Centrifugal Compressor through Inducer Casing Treatment

2016 ◽  
Vol 2016 ◽  
pp. 1-19
Author(s):  
V. V. N. K. Satish Koyyalamudi ◽  
Quamber H. Nagpurwala
Keyword(s):  
Mass Flow ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Treatment Technique ◽  
Centrifugal Compressors ◽  
Stall Margin ◽  
Casing Treatment ◽  
Operating Range ◽  
Stable Operating ◽  
Stall Margin Improvement

The increasing trend of high stage pressure ratio with increased aerodynamic loading has led to reduction in stable operating range of centrifugal compressors with stall and surge initiating at relatively higher mass flow rates. The casing treatment technique of stall control is found to be effective in axial compressors, but very limited research work is published on the application of this technique in centrifugal compressors. Present research was aimed to investigate the effect of casing treatment on the performance and stall margin of a high speed, 4 : 1 pressure ratio centrifugal compressor through numerical simulations using ANSYS CFX software. Three casing treatment configurations were developed and incorporated in the shroud over the inducer of the impeller. The predicted performance of baseline compressor (without casing treatment) was in good agreement with published experimental data. The compressor with different inducer casing treatment geometries showed varying levels of stall margin improvement, up to a maximum of 18%. While the peak efficiency of the compressor with casing treatment dropped by 0.8%–1% compared to the baseline compressor, the choke mass flow rate was improved by 9.5%, thus enhancing the total stable operating range. The inlet configuration of the casing treatment was found to play an important role in stall margin improvement.

scholarly journals Axial Flow Compressor Stability Enhancement: Circumferential T-Shape Grooves Performance Investigation

Aerospace ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 12
Author(s):  
Marco Porro ◽  
Richard Jefferson-Loveday ◽  
Ernesto Benini
Keyword(s):  
Vortex Breakdown ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Suction Side ◽  
Treatment Technique ◽  
Tip Leakage Flow ◽  
Stall Inception ◽  
Stall Margin ◽  
Casing Treatment ◽  
Stall Margin Improvement

This work focuses its attention on possibilities to enhance the stability of an axial compressor using a casing treatment technique. Circumferential grooves machined into the case are considered and their performances evaluated using three-dimensional steady state computational simulations. The effects of rectangular and new T-shape grooves on NASA Rotor 37 performances are investigated, resolving in detail the flow field near the blade tip in order to understand the stall inception delay mechanism produced by the casing treatment. First, a validation of the computational model was carried out analysing a smooth wall case without grooves. The comparisons of the total pressure ratio, total temperature ratio and adiabatic efficiency profiles with experimental data highlighted the accuracy and validity of the model. Then, the results for a rectangular groove chosen as the baseline case demonstrated that the groove interacts with the tip leakage flow, weakening the vortex breakdown and reducing the separation at the blade suction side. These effects delay stall inception, improving compressor stability. New T-shape grooves were designed keeping the volume as a constant parameter and their performances were evaluated in terms of stall margin improvement and efficiency variation. All the configurations showed a common efficiency loss near the peak condition and some of them revealed a stall margin improvement with respect to the baseline. Due to their reduced depth, these new configurations are interesting because they enable the use of a thinner light-weight compressor case as is desirable in aerospace applications.

scholarly journals Influence of Seal Cavity Leakage Flow on Compressor Performance Investigated with a Circumferentially Averaged Method

2021 ◽  
Vol 11 (2) ◽  
pp. 780
Author(s):  
Dong Liang ◽  
Xingmin Gui ◽  
Donghai Jin
Keyword(s):  
Flow Field ◽  
Pressure Ratio ◽  
Interaction Mechanism ◽  
Main Flow ◽  
Leakage Flow ◽  
Destructive Effect ◽  
Through Flow ◽  
Compressor Performance ◽  
Overall Performance ◽  
Flow Blockage

In order to investigate the effect of seal cavity leakage flow on a compressor’s performance and the interaction mechanism between the leakage flow and the main flow, a one-stage compressor with a cavity under the shrouded stator was numerically simulated using an inhouse circumferentially averaged through flow program. The leakage flow from the shrouded stator cavity was calculated simultaneously with main flow in an integrated manner. The results indicate that the seal cavity leakage flow has a significant impact on the overall performance of the compressor. For a leakage of 0.2% of incoming flow, the decrease in the total pressure ratio was 2% and the reduction of efficiency was 1.9 points. Spanwise distribution of the flow field variables of the shrouded stator shows that the leakage flow leads to an increased flow blockage near the hub, resulting in drop of stator performance, as well as a certain destructive effect on the flow field of the main passage.

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