Numerical Investigation of Aerodynamic Radial and Axial Impeller Forces in a Turbocharger

Raetz, H.; Kammeyer, Jasper; Natkaniec, Christoph; Seume, Joerg R.

doi:10.1115/gt2011-46360

Cited by 5 publications

(3 citation statements)

References 7 publications

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“…The variation range (max-min) assigned at the LE is greater (in percentage terms) and this is related to a third contribution factor, i.e., the axial thrust on rotor bearings. On this issue many authors investigated [13,14] and discussed that the thrust contribution from the leakage flow in the rotor backside cavity is usually greater than the momentum variation contribution due to blade flow deflection. The overall thrust tends to push the rotor toward the shroud at the LE resulting in a further reduction of the existing gap (while at the TE the axial thrust has no effect on the clearance).…”

Section: Input Uncertaintiesmentioning

confidence: 99%

Uncertainty Quantification Methodologies Applied to the Rotor Tip Clearance Effect in a Twin Scroll Radial Turbine

Cravero

Ottonello

2020

Fluids

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In the last three decades computer simulation tools have achieved wide spread use in the design and analysis of engineering devices. This has shortened the overall product design cycle (physical experiments may be impossible during early design stages) and it has also provided better understanding of the operating behavior of the systems under investigation. As a consequence numerical simulation have led to a reduction of physical prototyping and to lower costs for manufacturing production chains. Despite this success, it remains difficult to provide objective confidence levels in quantitative information derived from numerical predictions. The complexity arises from the amount of uncertainties related to the inputs of any computation attempting to represent a physical system. This paper focuses on geometrical sources of uncertainty in the field of CFD applied to twin scroll radial turbines. In particular it has been investigated the effect of uncertainties on tip clearance values at rotor blade leading edge and trailing edge on selected turbine performance parameters. The analysis shows the use of the Surrogate-based uncertainty quantification technique that has been setup by the authors in the Dakota® environment. The polynomial chaos expansion method has been applied to the same case. The comparison of the results coming from the different approaches and the discussion of the pros and cons related to each technique lead to interesting conclusions, which are proposed as guidelines for future UQ applications on the theme of CFD applied to radial turbines.

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Section: Input Uncertaintiesmentioning

confidence: 99%

Uncertainty Quantification Methodologies Applied to the Rotor Tip Clearance Effect in a Twin Scroll Radial Turbine

Cravero

Ottonello

2020

Fluids

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“…However, the total axial thrust predicted by the two methods was in good agreement with the experimental measurements. Raetz et al 18 analyzed the radial and axial forces on the impeller and concluded that the radial force on the impeller was much smaller than the axial force. Most of the aerodynamic parameters were evenly distributed in the circumferential direction, and the radial pressure gradient was mainly caused by the centrifugal force.…”

Section: Introductionmentioning

confidence: 99%

Effect of the hub cavity leakage on the aerodynamic performance and strength characteristics of the 150 kW SCO₂ centrifugal compressor

Cao

Deng

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part A:

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The hub cavity leakage has large effect on the aerodynamic performance on the Supercritical carbon dioxide (SCO2) centrifugal compressor. In this paper, the aerodynamic performance and strength characteristics of the 150 kW SCO2 centrifugal compressor with the hub cavity were numerically investigated using three-dimensional Reynolds-Averaged Navier-Stokes (RANS) and [Formula: see text] turbulence model. The high precision physical properties tables of SCO2 were used to calculate the SCO2 property parameters across the centrifugal compressor flow passages. The aerodynamic performance of the 150 kW SCO2 centrifugal compressor without and with the hub cavity and the labyrinth seal at different mass flow coefficients was compared. The equivalent (von-Mises) stress and the deformation on the SCO2 centrifugal impeller were obtained by the combination of the aerodynamic pressure and centrifugal force calculation. The results show that the isentropic efficiency of the SCO2 centrifugal compressor without and with the hub cavity and the labyrinth seal at the designed flow coefficient equal 73.2% and 72.1% respectively. The effects of the hub cavity leakage on the pressure ratio of the SCO2 centrifugal compressor are limited. The hub cavity leakage decreases with the flow coefficient increasing. The similar isentropic efficiency of the SCO2 centrifugal compressor without and with the hub cavity and the labyrinth seal at the largest flow coefficient is obtained. The axial thrust of the SCO2 centrifugal compressor with the hub cavity and the labyrinth seal ranges from 1000N to 2000N at different flow coefficients, as well as keeps the same direction. The maximum equivalent (von-Mises) stress of the impeller is 109.95 MPa and less than the allowable stress 137 MPa (using 304 steel as the impeller material). The maximum deformation of the seal teeth is less than 0.003 mm. This work provides the reference of the compressor design and safety operation for the SCO2 centrifugal compressor.

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“…The backside cavity behind the rotor disk can affect the flow at rotor inlet and consequently turbine performance. The flow features within the cavity were investigated by Raetz et al [10] to calculate aerodynamic forces in a turbocharger. Results showed a flow structure with high total pressure gradients in the radial direction generated by centrifugal forces.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of the Performance of a Twin Scroll Radial Turbine at Different Operating Conditions

Cravero

Domenico

Ottonello

2019

International Journal of Rotating Machinery

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Twin scroll radial turbines are increasingly used for turbocharging applications, to take advantage of the pulsating exhaust gases. In spite of its relevance in turbocharging techniques, scientific literature about CFD applied to twin scroll turbines is limited, especially in case of partial admission. In the present paper a CFD complete model of a twin scroll radial turbine is developed in order to give a contribution to literature in understanding the capabilities of current industrial CFD approaches applied to these difficult cases and to develop performance index that can be used for turbine design optimization purposes. The flow solution is obtained by means of ANSYS CFX ® in a wide range of operating conditions in full and partial admission cases. The total-to-static efficiency and the mass flow parameter (MFP) have been calculated and compared with the experimental database in order to validate the numerical model. The purpose of the developed procedure is also to generate a database for twin scroll turbines useful for future applications. A comparison between performances obtained in different admission conditions was performed. In particular the analysis focused on the characterization of the flow at volute outlet/rotor inlet section. A flow distortion index at rotor inlet was introduced to correlate the turbine performance and the flow nonuniformities generated by the volute. Finally the influence of the backside cavity on the performance parameters is also discussed. The introduction of these new nonuniformity indices is proposed for volute design and optimization procedures.

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Numerical Investigation of Aerodynamic Radial and Axial Impeller Forces in a Turbocharger

Cited by 5 publications

References 7 publications

Uncertainty Quantification Methodologies Applied to the Rotor Tip Clearance Effect in a Twin Scroll Radial Turbine

Uncertainty Quantification Methodologies Applied to the Rotor Tip Clearance Effect in a Twin Scroll Radial Turbine

Effect of the hub cavity leakage on the aerodynamic performance and strength characteristics of the 150 kW SCO₂ centrifugal compressor

Numerical Simulation of the Performance of a Twin Scroll Radial Turbine at Different Operating Conditions

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Numerical Investigation of Aerodynamic Radial and Axial Impeller Forces in a Turbocharger

Cited by 5 publications

References 7 publications

Uncertainty Quantification Methodologies Applied to the Rotor Tip Clearance Effect in a Twin Scroll Radial Turbine

Uncertainty Quantification Methodologies Applied to the Rotor Tip Clearance Effect in a Twin Scroll Radial Turbine

Effect of the hub cavity leakage on the aerodynamic performance and strength characteristics of the 150 kW SCO2 centrifugal compressor

Numerical Simulation of the Performance of a Twin Scroll Radial Turbine at Different Operating Conditions

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Effect of the hub cavity leakage on the aerodynamic performance and strength characteristics of the 150 kW SCO₂ centrifugal compressor