Optimal Vaneless Diffuser Design For A High-End Centrifugal Compressor

Noukhez Ahmed, Taimoor Asim, Rakesh Mishra

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Turbochargers are widely used in the automotive industry to reduce engine emissions and to increase the power. Centrifugal compressors are an integral part of turbochargers. Centrifugal compressors comprises primarily of inducer, impeller, diffuser and volute. The diffuser has an important role in the isentropic efficiency of the compressor. Over the past few decades, researchers have been trying to increase the total-to-total compressor stage efficiency by altering the diffuser’s geometries. Many different methods have been adopted for this purpose, like pinching the diffuser walls, tilting the diffuser walls etc. Pinching increases the outer width of the diffuser while tilting provides an increased radial length. In the present study, both these methods have been used simultaneously. The primary benefit of doing so is to make the turbocharger compressor stage more compact in design, which is the current requirement of the automotive market. In order to investigate the effect of pinching and tilting of diffuser walls, a Computational Fluid Dynamics based solver has been used to predict the flow phenomena within the compressor, especially in the vaneless diffuser. Design of Experiments, using Taguchi’s method, has been incorporated in this study to statistically define the scope of the numerical work, and to obtain the optimal configuration of pinching and tilting that leads to maximum total-to-total compressor stage efficiency. The results depict that the compressor stage efficiency increases up to a tilt angle of 6.25º, after which it starts to decrease. Furthermore, the stage efficiency increases with increase of diffuser outlet width i.e., pinching the diffuser passage, however, this increasing trend has been observed up to an outlet width ratio of 1.23, after which the stage efficiency starts to decrease. Hence, the optimal diffuser model, based on the combined tilting and pinching results obtained, which leads to the maximum total-to-total compressor stage efficiency, has been identified and analysed.
LanguageEnglish
Title of host publication28th International Congress on Condition Monitoring and Diagnostic Engineering Management
Pages406-413
Number of pages8
Publication statusPublished - Sep 2018
Event28th International Congress of Condition Monitoring and Diagnostic Engineering - AAENDE, Buenos Aires, Argentina
Duration: 1 Dec 20154 Dec 2015
Conference number: 28

Conference

Conference28th International Congress of Condition Monitoring and Diagnostic Engineering
Abbreviated titleCOMADEM 2015
CountryArgentina
CityBuenos Aires
Period1/12/154/12/15

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Centrifugal compressors
Compressors
Taguchi methods
Automotive industry
Design of experiments
Computational fluid dynamics
Engines
Geometry

Cite this

Ahmed, N., Asim, T., & Mishra, R. (2018). Optimal Vaneless Diffuser Design For A High-End Centrifugal Compressor. In 28th International Congress on Condition Monitoring and Diagnostic Engineering Management (pp. 406-413)
Ahmed, Noukhez ; Asim, Taimoor ; Mishra, Rakesh. / Optimal Vaneless Diffuser Design For A High-End Centrifugal Compressor. 28th International Congress on Condition Monitoring and Diagnostic Engineering Management. 2018. pp. 406-413
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Ahmed, N, Asim, T & Mishra, R 2018, Optimal Vaneless Diffuser Design For A High-End Centrifugal Compressor. in 28th International Congress on Condition Monitoring and Diagnostic Engineering Management. pp. 406-413, 28th International Congress of Condition Monitoring and Diagnostic Engineering, Buenos Aires, Argentina, 1/12/15.

Optimal Vaneless Diffuser Design For A High-End Centrifugal Compressor. / Ahmed, Noukhez; Asim, Taimoor; Mishra, Rakesh.

28th International Congress on Condition Monitoring and Diagnostic Engineering Management. 2018. p. 406-413.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

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N2 - Turbochargers are widely used in the automotive industry to reduce engine emissions and to increase the power. Centrifugal compressors are an integral part of turbochargers. Centrifugal compressors comprises primarily of inducer, impeller, diffuser and volute. The diffuser has an important role in the isentropic efficiency of the compressor. Over the past few decades, researchers have been trying to increase the total-to-total compressor stage efficiency by altering the diffuser’s geometries. Many different methods have been adopted for this purpose, like pinching the diffuser walls, tilting the diffuser walls etc. Pinching increases the outer width of the diffuser while tilting provides an increased radial length. In the present study, both these methods have been used simultaneously. The primary benefit of doing so is to make the turbocharger compressor stage more compact in design, which is the current requirement of the automotive market. In order to investigate the effect of pinching and tilting of diffuser walls, a Computational Fluid Dynamics based solver has been used to predict the flow phenomena within the compressor, especially in the vaneless diffuser. Design of Experiments, using Taguchi’s method, has been incorporated in this study to statistically define the scope of the numerical work, and to obtain the optimal configuration of pinching and tilting that leads to maximum total-to-total compressor stage efficiency. The results depict that the compressor stage efficiency increases up to a tilt angle of 6.25º, after which it starts to decrease. Furthermore, the stage efficiency increases with increase of diffuser outlet width i.e., pinching the diffuser passage, however, this increasing trend has been observed up to an outlet width ratio of 1.23, after which the stage efficiency starts to decrease. Hence, the optimal diffuser model, based on the combined tilting and pinching results obtained, which leads to the maximum total-to-total compressor stage efficiency, has been identified and analysed.

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BT - 28th International Congress on Condition Monitoring and Diagnostic Engineering Management

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Ahmed N, Asim T, Mishra R. Optimal Vaneless Diffuser Design For A High-End Centrifugal Compressor. In 28th International Congress on Condition Monitoring and Diagnostic Engineering Management. 2018. p. 406-413