Assessment of Various Turbulence Models in a High Pressure Ratio Centrifugal Compressor With an Object Oriented CFD Code

Mangani, Luca; Casartelli, Ernesto; Mauri, Sebastiano

doi:10.1115/gt2011-46829

Cited by 8 publications

(13 citation statements)

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“…The inconsistency not only occurs in the current research, but was also reported by former researchers. 25,26 It is also noticed in Figure 6 that inconsistency also exists for the surge point prediction. In this steady case, the surge point is defined as the converged point with the highest backpressure.…”

Section: Optimization Methodsmentioning

confidence: 81%

Performance improvement of transonic centrifugal compressors by optimization of complex three-dimensional features

Zheng

2016

Proceedings of the Institution of Mechanical Engineers, Part G:

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Transonic centrifugal compressors with high efficiency and wide stable flow range are required in modern gas turbine engines. Blade design with complex three-dimensional features is one of the promising methods to further improve the performance of such cases. Aiming to increase the efficiency while maintaining similar level of the stable flow range, this article investigates aerodynamic potentials of complex three-dimensional features in a transonic centrifugal compressor by multi-point and multi-objective optimizations, in which the camber curves, the sweep feature, and the lean feature have been optimized. During the first round of optimizations, the aforementioned three groups of variables are optimized individually, and their sensitivities to the performance have been analyzed. When optimizing the camber curves, the best result shows an end-bend feature at the front of the hub section, and the efficiency is improved by 1.0% due to the lowered shock strength. When optimizing the sweep feature, the best result presents an S-shape leading edge and a forward sweep feature. The efficiency is increased by 0.5% because of the reduced wake region. The optimized lean feature only improves the efficiency by 0.2%, which shows its relatively low potential. The final round of optimizations couples both the camber curves and the sweep feature, and the best geometry combines both the end-bend and S-shape leading edge patterns. The peak efficiency and the choke mass flow rate have been increased by 2.2% and 8.1%, respectively, which is owing to the combination of the lowered shock strength by optimized camber curves and the reduced wake region by optimized sweep feature. The result indicates significant potential of complex three-dimensional features to improve the performance of transonic centrifugal compressors.

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Section: Optimization Methodsmentioning

confidence: 81%

Performance improvement of transonic centrifugal compressors by optimization of complex three-dimensional features

Zheng

2016

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…Furthermore left operating range is correctly computed if the unsteadiness are resolved. Finally the possibility to model hub cavity in open centrifugal compressor impellers and the possibility of using non-matching blocks for tip domain should increase the accuracy of CFD computations on predicting operating range and quantitative level of efficiency that has been historically a weak point for open impellers like shown in [21] …”

Section: Discussionmentioning

confidence: 99%

“…Numerical approximations and turbulence modeling increase also the source of errors. According to the study of Mangani [21], more advanced turbulence models are not sufficient to capture the discrepancy between experimental and numerical results, especially at high pressure ratios and high mass-flow on open centrifugal compressor impellers. In the present study full cavity meshing has been included and accurate reproduction of the stage geometry including fillets and upstream stage has been used.…”

Section: Overall Performancementioning

confidence: 99%

Cavity Flow Modeling in an Industrial Centrifugal Compressor Stage at Design and Off-Design Conditions

Guidotti

Naldi

Tapinassi

et al. 2012

Volume 8: Turbomachinery, Parts A, B, and C

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Numerical tools and test equipments used in the design and validation of modern centrifugal compressor stages need to be at the state-of-the-art. In particular, a big effort is currently made to correctly model secondary flows that play a relevant role in the accuracy of the performance prediction. This paper presents the flow analysis of a high efficiency centrifugal compressor stage using high accurate computational fluid dynamics with a particular attention to the cavity flows modeling. Experimental data were also available and used to validate the numerical results. The key experimental data coming from an advanced FRAPP (Fast Response Aerodynamic Pressure Probe) and traditional probes are presented in the study as overall performance and flow features details. Test data are in fact necessary to validate and continuously improve the numerical techniques.The geometry of the stage including full modeling of the secondary flows cavities were faithfully reproduced in the computational model. The availability of new in-house automated tools for cavity meshing allow compressor aero-designers to ac- * Reference author. curately resolve leakage flows with a reasonable increase in computational and user time.The results of the computational model were in excellent agreement with the experimental data both in terms of overall performance and main flow field structures. Also details of the flow features inside the cavities matched the test data very well. Only using high accurate geometry modeling including leakage flows was possible to capture important flow features that instead were not correctly simulated with simplified computational models.

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“…The stage averaging at the interface incurs a one-time mixing loss which accounts for timeaveraged interaction effects. The Shear Stress Transport (SST) turbulence model of Menter (1994) was employed because of its success in modeling flows in an adverse pressure gradient, and Mangani, Casartelli, and Mauri (2012) have proved that this turbulence model is suitable for centrifugal compressor calculations. A 'high resolution' advection scheme (ANSYS, 2011a) was employed for all equations except for the turbulence equation, which uses a first-order upwind scheme.…”

Section: Numerical Schemementioning

confidence: 99%

The effect of impeller–diffuser interactions on diffuser performance in a centrifugal compressor

Zhao

Liu

et al. 2016

Engineering Applications of Computational Fluid Mechanics

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The unsteady phenomenon abounds in centrifugal compressors and significantly affects the compressor performance. In this paper, unsteady simulations are carried out to investigate the aerodynamic performance of a process-unshrouded centrifugal compressor and the unsteady mechanism in the vaned diffuser. The predicted stage performance and pressure fluctuations at some locations are in good agreement with experimental data. The predicted main pressure fluctuation frequency spectrums at the diffuser inlet and outlet are consistent with the measured results. The results indicate that at the inlet of the diffuser there are two pressure peaks in a passage cycle. The higher pressure peak relates to the impeller wake and the lower peak is connected with the vortex generated at the diffuser's leading edge. With a decrease in the mass flow coefficient, the vortex core region becomes larger and the lower pressure peak becomes more pronounced. The change in circumferential flow angle at the diffuser inlet is mainly responsible for the unsteadiness in the diffuser flow field, which in turn affects the inlet incidence of the diffuser vane and the vane loading distributions. ARTICLE HISTORY

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Assessment of Various Turbulence Models in a High Pressure Ratio Centrifugal Compressor With an Object Oriented CFD Code

Cited by 8 publications

References 0 publications

Performance improvement of transonic centrifugal compressors by optimization of complex three-dimensional features

Performance improvement of transonic centrifugal compressors by optimization of complex three-dimensional features

Cavity Flow Modeling in an Industrial Centrifugal Compressor Stage at Design and Off-Design Conditions

The effect of impeller–diffuser interactions on diffuser performance in a centrifugal compressor

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