LDV Characterization of Unsteady Vaned Diffuser Flow in a Centrifugal Compressor

Gooding, William J.; Fabian, John C.; Key, Nicole L.

doi:10.1115/gt2019-90476

Cited by 6 publications

(4 citation statements)

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“…However, unsteadiness is one such flow driver that can significantly impact the measured flow field. Recent experimental measurements of the unsteady velocity field through the diffuser show that unsteadiness persists further into the diffuser passage than typically assumed [21], suggesting a strong influence of unsteady effects on the flow field. The methodology used for model selection herealways stepping towards a more physically realistic modelwas done to minimize the impact of omitted flow drivers.…”

Section: Frozen Rotor Resultsmentioning

confidence: 95%

The Impact of Various Modelling Decisions on Flow Field Predictions in a Centrifugal Compressor

Gooding

Meier

Key

2020

Volume 2E: Turbomachinery

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Computational tools have become increasingly important in design and research applications in recent years due to increasing computational resources. In most cases, model geometry and flow-physics are simplified to reduce the complexity of the computational model. While this was necessary historically, modern computational tools are capable of including realistic features such as fillets, surface roughness, and heat transfer. This work presents extensive and systematic numerical results from a simulation of a centrifugal compressor stage for an aero-engine application. Numerical results are compared to detailed experimental data to investigate the effect of various modelling decisions, including turbulence models, on the predicted aerodynamics developing through the diffuser passage. Roughness and the inclusion of fillets significantly impact the flow development, especially with the SST turbulence model. This approach leads to the conclusion that the BSL-EARSM model is best able to predict the experimentally determined diffuser flow profiles and overall performance trends with the inclusion of the previously mentioned model features. Additionally, the misleading conclusions can be reached if modelling decisions are based on merely matching overall performance values. Finally, frozen rotor simulations are used to roughly approximate the impact of unsteadiness on the flow field. The results show a significant impact and also that the inclusion of approximate unsteady effects tends to further improve the predictive capability of the computational models that were considered.

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Section: Frozen Rotor Resultsmentioning

confidence: 95%

The Impact of Various Modelling Decisions on Flow Field Predictions in a Centrifugal Compressor

Gooding

Meier

Key

2020

Volume 2E: Turbomachinery

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“…The diffuser throat is located in this region and the flow is highly unsteady. Gooding et al [15] concluded that steady CFD computations do not accurately predict the flow in this region, specifically on the suction surface. The trailing edge pressure deviates by less than 1% on both the PS and SS which suggests the steady CFD appropriately predicts the static pressure rise in the diffuser.…”

Section: Instrumentationmentioning

confidence: 99%

Considerations for Using Additive Manufacturing Technology in Centrifugal Compressor Research

Meier

Gooding

Fabian

et al. 2020

Journal of Engineering for Gas Turbines and Power

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An additive manufactured (AM) vaned diffuser for use in a centrifugal compressor research facility was designed and implemented. Utilizing an AM process to manufacture the diffuser reduces the long lead time that is associated with conventionally manufactured diffusers, and it increases the instrumentation capabilities within the flow path. Several AM techniques and a variety of plastic and metal materials were evaluated for this application. A high-temperature, stereolithography (SL) resin was chosen because of the tight dimensional tolerances maintained by the SL process. Utilizing a high-temperature plastic also results in manufacturing costs that are significantly less than using a metal material. Samples of the chosen material were subjected to mechanical testing to investigate the effects of build direction and to verify its properties in the high-temperature compressor environment. To fit within the manufacturing space of an SL machine, the AM diffuser consists of seven radially symmetric sections that are assembled to form a complete flow path. Considerations for modifying the research facility to allow for this unique installation are presented. Precision measurements of the AM components were obtained to compare printed and modeled geometry, and they demonstrate close alignment of flow path dimensions.

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“…CFD techniques are currently used for the design and flow analysis of turbomachinery, even with fully 3D stage configuration. Complete, fully 3D unsteady analysis can be performed to study the component coupling near surge conditions [26] or to simulate a complete surge cycle [27]. The same authors performed unsteady simulations at near surge conditions in centrifugal compressors with vaned diffusers [28].…”

Section: Introductionmentioning

confidence: 99%

Simulation and Modeling of Ported Shroud Effects on Radial Compressor Stage Stability Limits

Cravero

Leutcha

2022

Energies

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The design features of a centrifugal compressor must guarantee high performance and a wide operating range. The ported shroud was developed specifically to extend the operating limit. It is a passive flow control device based on a cavity for flow recirculation to avoid blade passage blocking in near surge conditions. A CFD simulation campaign using a simplified model identified the differences in the performance of the centrifugal compressor with ported shroud, compared to the baseline case. The use of a stability criterion to determine the limit mass flow rate, developed in a previous study by the authors, highlighted and quantified the extension of the surge margin in the case with ported shroud for different rotational speeds. An increase in the surge margin of 11% was detected at design speed, but with a lower trend at higher speeds. An in-depth flow analysis showed the main physical mechanisms in the compressor that occur for different operating conditions: at near surge conditions the cavity recirculates the low momentum flow located in the inducer region; it re-energizes the mainstream decreasing the circumferential velocity component; an improvement of up to 7% of the pressure ratio was obtained. Instead, at best efficiency conditions the flow recirculation worsens the performance by reducing the flow incidence at the rotor leading edge. Finally, using unsteady simulations with a complete 3D model and with the application of the stability criterion it was possible to confirm that the ported shroud can effectively extend the operating range.

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LDV Characterization of Unsteady Vaned Diffuser Flow in a Centrifugal Compressor

Cited by 6 publications

References 0 publications

The Impact of Various Modelling Decisions on Flow Field Predictions in a Centrifugal Compressor

The Impact of Various Modelling Decisions on Flow Field Predictions in a Centrifugal Compressor

Considerations for Using Additive Manufacturing Technology in Centrifugal Compressor Research

Simulation and Modeling of Ported Shroud Effects on Radial Compressor Stage Stability Limits

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