Aerodynamic Investigation of a Composite Low-Speed Fan for UHBR Application

Rodrigues, Martin; Soulat, Laurent; Paoletti, Benoît; Ottavy, Xavier; Brandstetter, Christoph

doi:10.1115/gt2020-14915

Cited by 7 publications

(23 citation statements)

References 24 publications

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“…In order to measure structural vibrations which interact with the aerodynamic or acoustic disturbances, the same method can be applied to rotor-strain gauges on different rotor blades. Filtered on specific vibration eigenmodes, the dominant nodal diameter can be calculated [28]. Fig.…”

Section: Analysis Methodsmentioning

confidence: 99%

“…Nodal diameter N v = 3 is present before rotating stall forms at revolution 0. More detail on this NSV interaction is given in [28].…”

Section: Analysis Methodsmentioning

confidence: 99%

“…3. A UHBR low speed transonic fan constructed from composite material that has been developed by Safran Aircraft Engines 1 was used as a test vehicle [28]. The machine core is instrumented with pressure and temperature sensors distributed from the bellmouth shaped intake to the throttle mechanism at various meridian positions, on the hub and casing.…”

Section: Test Case: Enoval Low-speed Fanmentioning

confidence: 99%

“…At the relevant speedline the blade passing frequency is below 3kHz, the dynamic inlet pressure approximates 8000 Pa. The main parameters of the investigated fan stage are summarized in Table 1 [28].…”

Section: Test Case: Enoval Low-speed Fanmentioning

confidence: 99%

“…In addition to the high-speed core compressor (hub-to-tip ratio ∼ 0.5) the model has been validated for the low-speed transonic fan described in this study (hub-to-tip ratio << 0.5, experiment) [28], the Open-Test-Case fan ECL5/CATANA (hub-to-tip ratio ∼ 0.3, numerics) [27], and a transonic booster (ENOVAL, hub-to-tip ratio > 0.5, experiment and numerics). Its general applicability indicates that the physical phenomenon, which is limited to the outer section of the rotor (> 90% span) [19] is independent of the hub-to-tip ratio.…”

Section: Model Descriptionmentioning

confidence: 99%

See 4 more Smart Citations

Interpretation of Stall Precursor Signatures

Brandstetter

Ottavy

Paoletti

et al. 2021

Journal of Turbomachinery

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A specific phenomenon that has been observed in many experimental studies on turbomachinery compressors and fans is discussed under the term ‘rotating instabilities’. It is associated to a local aerodynamic phenomenon, typically occurring in the tip region at highly loaded near stall conditions and often linked to blade vibrations. Even though the effect has been discussed over more than two decades, a very ambiguous interpretation still prevails. A particular problem is that certain signatures in measurement data are often considered to characterize the phenomenon despite possible misinterpretations. The present paper illustrates that a specific image of a pulsating disturbance that has been established in the 1990s needs to be reconsidered. At the example of a recent investigation on a composite fan the difficulties concerning sensor placement and post-processing techniques is discussed with a focus on spectral averaging, isolation of non-synchronous phenomena and multi-sensor cross-correlation methods.

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Section: Analysis Methodsmentioning

confidence: 99%

“…Nodal diameter N v = 3 is present before rotating stall forms at revolution 0. More detail on this NSV interaction is given in [28].…”

Section: Analysis Methodsmentioning

confidence: 99%

Section: Test Case: Enoval Low-speed Fanmentioning

confidence: 99%

Section: Test Case: Enoval Low-speed Fanmentioning

confidence: 99%

Section: Model Descriptionmentioning

confidence: 99%

See 3 more Smart Citations

Interpretation of Stall Precursor Signatures

Brandstetter

Ottavy

Paoletti

et al. 2021

Journal of Turbomachinery

Self Cite

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Interpretation of stall precursor signatures-stable instabilities

2022

Self Cite

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A specific phenomenon that has been observed in many experimental studies on turbomachinery compressors and fans is discussed under the term “rotating instabilities”. It is associated to a local aerodynamic phenomenon, typically occurring in the tip region at highly loaded near stall conditions and often linked to blade vibrations. Even though the effect has been discussed over more than two decades, a very ambiguous interpretation still prevails. A particular problem is that certain signatures in measurement data are often considered to characterize the phenomenon despite possible misinterpretations. The present paper illustrates that a specific image of a pulsating disturbance that has been established in the 1990s needs to be reconsidered. At the example of a recent investigation on a composite fan the difficulties concerning sensor placement and post-processing techniques is discussed with a focus on spectral averaging, isolation of non-synchronous phenomena and multi-sensor cross-correlation methods.

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Suppression of Nonsynchronous Vibration Through Intentional Aerodynamic and Structural Mistuning

Stapelfeldt

Brandstetter

2021

Journal of Turbomachinery

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Non-synchronous vibrations (NSV) arising near the stall boundary of compressors are a recurring and potentially safety-critical problem in modern axial compressors and fans. Recent research has improved predictive capabilities and physical understanding of NSV but prevention measures are still lacking. This paper addresses this by systematically studying the influence of aerodynamic and structural mistuning on NSV. This is achieved by incorporating mistuning effects in a validated linear model, in which individual blade modes are modelled as single-degree of freedom mass oscillators coupled by a convected aerodynamic disturbance term. The results demonstrate that both structural and aerodynamic mistuning are effective. While structural mistuning improves stability by preventing aero-structure lock-in, aerodynamic mistuning, which locally reduces the tip blockage, attenuates the aerodynamic disturbance causing NSV. In the latter case, the circumferentially-averaged conditions are shown to be most influential, while the pattern plays a minor role. A combination of moderate aerodynamic and structural mistuning (1%) was also found to be effective. These findings are relevant for design decisions, demonstrating that small blade-to-blade variations can suppress NSV.

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Aerodynamic Investigation of a Composite Low-Speed Fan for UHBR Application

Cited by 7 publications

References 24 publications

Interpretation of Stall Precursor Signatures

Interpretation of Stall Precursor Signatures

Interpretation of stall precursor signatures-stable instabilities

Suppression of Nonsynchronous Vibration Through Intentional Aerodynamic and Structural Mistuning

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