Predictions of Turbulent Flow for the Impeller of a NASA Low-Speed Centrifugal Compressor

Guleren, K M; Afgan, Imran; Turan, Ali

doi:10.1115/1.3140824

Cited by 18 publications

(10 citation statements)

References 11 publications

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“…Remarkable is the formation of recirculation bubbles in the exit region of the impeller, which do not seem to have large influence on the flow further downstream. The occurrence of the flow reversal and the turbulence distribution in the impeller at design operating conditions has been also reported and analysed by Guleren et al [26].…”

Section: Resultsmentioning

confidence: 86%

Flow phenomena leading to surge in a centrifugal compressor

Semlitsch

Mihăescu

2016

Energy

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Surge is a global flow instability occurring in centrifugal compressors at low mass-flow rate operation. Due to its violent nature, it is the limiting factor for operability. To enhance the operating range, understanding of the flow instability inception when approaching surge is essential. Therefore, the flow evolution along a speed line is analysed by performing unsteady, three-dimensional flow simulations using a centrifugal compressor geometry with ported shroud. A stable operating condition, at high mass-flow rates, is compared to lower mass-flow rate operating conditions close to and at surge. The particularities of the flow-fields are analysed and described. A smooth flow-field is observed for the stable operating condition, whereas flow reversal manifesting as tip leakage at the outer periphery of the impeller occurs for all o↵-design operating conditions. The reversed flow exhibits swirling motion in the impeller rotation direction. This induces a globally swirling flow upstream of the impeller, which influences the flow incidence angles at the blades and hence, their e ciency. Proper orthogonal decomposition and dynamic mode decomposition have been performed to analyse the flow structures appearing with surge more thoroughly. For the lowest mass-flow rate operating condition, low frequency modes describing the filling and emptying processes during surge have been found.

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Section: Resultsmentioning

confidence: 86%

Flow phenomena leading to surge in a centrifugal compressor

Semlitsch

Mihăescu

2016

Energy

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“…the variable vaned diffusers, and the variable inlet guide vanes [1][2][3][4]. Passive flow control devices including casing treatment [5][6][7][8], (which includes the ported shroud,) inducer casing bleed system [7][8][9], and internal recirculation or ring groove arrangements [10][11][12]. From the above mentioned devices, the variable inlet guide vanes and variable vaned diffuser introduce an efficiency penalty along with a gain of wider compressor operability range.…”

Section: Introductionmentioning

confidence: 99%

“…Several Large Eddy Simulation (LES) investigations have been performed analyzing the flow phenomena occurring in centrifugal compressors [11,12,15]. Flow separation and recirculation bubbles were accurately predicted and the LES approach results were more accurate in predicting the performance parameters and the flow structure details than Reynolds Averaged Navier-Stokes (RANS) simulations.…”

Section: Introductionmentioning

confidence: 99%

Numerical Flow Analysis of a Centrifugal Compressor with Ported and without Ported Shroud

Semlitsch¹,

Jyothishkumar²,

Mihăescu³

et al. 2014

SAE Technical Paper Series

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Turbochargers are commonly used in automotive engines to increase the internal combustion engine performance during off design operation conditions. When used, a most wide operation range for the turbocharger is desired, which is limited on the compressor side by the choke condition and the surge phenomenon. The ported shroud technology is used to extend the operable working range of the compressor, which permits flow disturbances that block the blade passage to escape and stream back through the shroud cavity to the compressor inlet. The impact of this technology on a speed-line at near optimal operation condition and near surge operation condition is investigated. A numerical study investigating the flow-field in a centrifugal compressor of an automotive turbocharger has been performed using Large Eddy Simulation. The wheel rotation is handled by the numerically expensive sliding mesh technique. In this analysis, the full compressor geometry (360 deg) is considered. Numerical solutions with and without ported shroud for a near optimal operation condition and near-surge operation condition. The flow-field of the different cases is analyzed to elucidate the functionality of the ported shroud. In agreement with previous observations, it was found that the ported shroud reduces the flow disturbances in the blade passage for all operating conditions. However, the compressor efficiency for the off-design operation condition was found to be higher without the ported shroud, supporting the findings reported recently by an experimental investigation. The computational results are validated with experimental measurements in terms of the performance parameters and available Particle Image Velocimetry data.

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“…A second-order central differencing scheme was used for flow parameters, whereas the turbulent properties were discretized using the van Leer scheme (Van Leer [ 55 ]). The numerical treatment and discretization techniques utilized in this study have already been extensively benchmarked over a wide range of thermal-hydraulic and renewable energy configurations, see Afgan et al [ 56 ], Filippone and Afgan [ 57 ], Guleren et al [ 58 ], Han et al [ 59 ], Wu et al [ 60 ], Wu et al [ 61 ], Wu et al [ 62 ], Kahil et al [ 63 ], Benhamadouche et al [ 64 ], Nguyen et al [ 65 ], Ejeh et al [ 66 ], Ejeh et al [ 67 ], Revell et al [ 68 ], Ahmed et al [ 69 ], Ahmed et al [ 70 ], McNaughton et al [ 71 ] and Abed et al [ 72 ]. The boundary conditions applied in the current study are summarized below:…”

Section: Numerical Modelingmentioning

confidence: 99%

Thermal-Hydraulic Analysis of Parabolic Trough Collectors Using Straight Conical Strip Inserts with Nanofluids

et al. 2021

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In this study, we numerically investigated the effect of swirl inserts with and without nanofluids over a range of Reynolds numbers for parabolic trough collectors with non-uniform heating. Three approaches were utilized to enhance the thermal-hydraulic performance—the variation of geometrical properties of a single canonical insert to find the optimized shape; the use of nanofluids and analysis of the effect of both the aforementioned approaches; the use of swirl generators and nanofluids together. Results revealed that using the straight conical strips alone enhanced the Nusselt number by 47.13%. However, the use of nanofluids along with the swirl generators increased the Nusselt number by 57.48%. These improvements reduced the thermal losses by 22.3% for swirl generators with nanofluids, as opposed to a reduction of only 15.7% with nanofluids alone. The investigation of different swirl generator designs showed various levels of improvements in terms of the overall thermal efficiency and thermal exergy efficiency. The larger swirl generator (H30mm-θ30°-N4) with 6% SiO2 nanofluids was found to be the optimum configuration, which improved the overall collector efficiency and thermal exergy by 14.62% and 14.47%, respectively.

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Predictions of Turbulent Flow for the Impeller of a NASA Low-Speed Centrifugal Compressor

Cited by 18 publications

References 11 publications

Flow phenomena leading to surge in a centrifugal compressor

Flow phenomena leading to surge in a centrifugal compressor

Numerical Flow Analysis of a Centrifugal Compressor with Ported and without Ported Shroud

Thermal-Hydraulic Analysis of Parabolic Trough Collectors Using Straight Conical Strip Inserts with Nanofluids

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