Mechanisms to reduce the blade passing frequency tone for subsonic low-count OGV fans

Schade, Stephen; Jaron, Robert; Moreau, Antoine; Guérin, Sébastien

doi:10.1016/j.ast.2021.107083

Cited by 4 publications

(9 citation statements)

References 25 publications

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“…Reducing the tonal interaction noise is particularly relevant for low-count OGV fans, as these designs may have a tonal disadvantage. Contrary to conventional fan designs, the usually dominant blade-passing frequency tone may no longer be cut off, since fewer stator than rotor blades are used [6]. Due to the described effect, for both low-count OGV fans, the tonal disadvantage is eliminated, as the results indicate a significant tonal noise reduction compared to the baseline fan.…”

Section: Introductionmentioning

confidence: 99%

“…Analytical and numerical studies on low-speed fan stages indicate that the excitation of tonal rotor-stator interaction noise is significantly affected by the propagation angles of the acoustic modes relative to the stator leading edge angle [2,5,6]. In [6], an analytical and numerical acoustic investigation of fan stages with fewer stator than rotor blades is performed. These designs are called low-count outer guide vane (OGV) fans [2,6].…”

Section: Introductionmentioning

confidence: 99%

“…In [6], an analytical and numerical acoustic investigation of fan stages with fewer stator than rotor blades is performed. These designs are called low-count outer guide vane (OGV) fans [2,6]. It is shown that, for certain blade count numbers, a tonal advantage is achieved if the propagation angles of the dominantly excited modes are nearly parallel to the stator leading edge angle [2,6].…”

Section: Introductionmentioning

confidence: 99%

“…These designs are called low-count outer guide vane (OGV) fans [2,6]. It is shown that, for certain blade count numbers, a tonal advantage is achieved if the propagation angles of the dominantly excited modes are nearly parallel to the stator leading edge angle [2,6]. In recent measurements on a low-speed fan stage, the effect was also confirmed experimentally in design operating conditions [7].…”

Section: Introductionmentioning

confidence: 99%

“…A detailed description of the procedure applied to the RANS-based noise prediction and blade count variation with PropNoise is given in [2,6].…”

mentioning

confidence: 99%

See 4 more Smart Citations

Smart Blade Count Selection to Align Modal Propagation Angle with Stator Stagger Angle for Low-Noise Ducted Fan Designs

Schade,

Jaron,

Klähn

et al. 2024

Aerospace

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The rotor–stator interaction noise is a major source of fan noise. Especially for low-speed fan stages, the tonal component is typically a dominant noise source. A challenge is to reduce this tonal noise, as it is typically perceived as unpleasant. Therefore, in this paper, we analytically, numerically and experimentally investigate an acoustic effect to lower the tonal noise excitation. Our study on an existing low-speed fan indicates a reduction in tonal interaction noise of more than 9 dB at the source if the excited acoustic modes propagate parallel to the stator leading edge angle. Moreover, a design-to-low-noise approach is demonstrated in order to apply this effect to two new fan stages with fewer stator than rotor blades. The acoustic design of both fans is determined by an appropriate choice of the rotor and stator blade numbers in order to align the modal propagation angle with the stator stagger angle. The blade geometries are obtained from aerodynamic optimization. Both fans provide similar aerodynamic but opposing acoustic radiation characteristics compared to the baseline fan and a significant tonal noise reduction resulting from the impact of the modal propagation angle on noise excitation. To ensure that this effect can also be applied to other low-speed fans, a design rule is derived and validated.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…A detailed description of the procedure applied to the RANS-based noise prediction and blade count variation with PropNoise is given in [2,6].…”

mentioning

confidence: 99%

See 3 more Smart Citations

Smart Blade Count Selection to Align Modal Propagation Angle with Stator Stagger Angle for Low-Noise Ducted Fan Designs

Schade,

Jaron,

Klähn

et al. 2024

Aerospace

Self Cite

View full text Add to dashboard Cite

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Ducted fans for hybrid electric propulsion of small aircraft

et al. 2022

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This paper presents a method for modeling ducted fan propulsion systems for hybrid-electrically driven small aircraft based on mean line flow analysis methods. Studies of the essential design parameters provide the basis for a discussion of potential advantages when compared to free propellers, as well as possible new fields of application for the ducted fan. A two-seater aircraft, equipped with two ducted fans powered by a combustion engine and additionally by a parallel hybrid electric start-boost drive, is used as a reference application case. The fan performance characteristics are described with the aid of aero mean line flow analysis methods and semi-empirical loss correlations. Physics-based methods are applied to assess the nacelle drag and noise emissions. The combustion engine and electric motor performance are described using maps. The ducted fan design variables are investigated to identify the main trade-offs and favorable designs for the target aircraft mission, with special attention to noise. The results show that the performance of fixed pitch fans benefits strongly from hybridization. Ducted fans can also operate considerably more quietly than is required by current certification standards. The physics-based design method presented here can be used for conceptual design and performance prediction of ducted fan propulsion systems, which may be especially interesting if low noise emissions are required.

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The noise-generating mechanism of rod-airfoil configuration and the effect of spanwise length on noise prediction

Han

Hong

et al. 2023

Aerospace Science and Technology

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Mechanisms to reduce the blade passing frequency tone for subsonic low-count OGV fans

Cited by 4 publications

References 25 publications

Smart Blade Count Selection to Align Modal Propagation Angle with Stator Stagger Angle for Low-Noise Ducted Fan Designs

Smart Blade Count Selection to Align Modal Propagation Angle with Stator Stagger Angle for Low-Noise Ducted Fan Designs

Ducted fans for hybrid electric propulsion of small aircraft

The noise-generating mechanism of rod-airfoil configuration and the effect of spanwise length on noise prediction

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