Comparative study of different analytical approaches for modelling the transmission of sound waves through turbomachinery stators

Behn, Maximilian; Tapken, Ulf; Puttkammer, Peter; Hagmeijer, Rob; Thouault, N.

doi:10.2514/6.2016-2927

Cited by 5 publications

(2 citation statements)

References 9 publications

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“…In recent measurements on a low-speed fan stage, the effect was also confirmed experimentally in design operating conditions [7]. Regarding the transmission of sound through rotor or stator blade rows, a similar effect is known as the "modal condition" [8,9].…”

Section: Introductionmentioning

confidence: 70%

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: 70%

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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“…As the radial eigenvalue s mn only depends on the respective mode orders and the hub-to-tip ratio, the axial wave number scales inversely proportional to the shroud radius under the assumption that all dimensionless quantities are held constant. Using the definition of the acoustic propagation angle in accordance with Behn et al (Behn et al, 2016).…”

Section: Dimensional Analysismentioning

confidence: 99%

Aeroacoustic Numerical Investigation of a Scaled Compressor Cascade

Lohse¹,

Moreau²,

Fischer³

et al. 2020

Proceedings of Global Power &Amp; Propulsion Society

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In order to further develop technologies to reduce noise emissions of aero engines, an understanding of the noise propagation through compressor blade rows of modern turbofan engines is of major importance. To enable more detailed experimental investigations of the sound propagation in aero engines, engine components or stages have to be scaled for an installation into test rigs that allow for experiments under acoustically optimized boundary conditions. The main focus of the present work is thus to discuss a scaling approach that ensures both aerodynamic and aeroacoustic similarity between a given test rig and engine. For that purpose, a stator row of a four-stage high-speed axial compressor (4AC) based on the test rig at the Institute of Turbomachinery and Fluid Dynamics (TFD) at the Leibniz University Hanover is scaled to fit into the TFD's Aeroacoustic Wind Tunnel (AWT). Numerical investigations based on multiple modeling approaches are performed to verify a similar aeroacoustic behaviour in both test rigs. Reynolds-Averaged Navier-Stokes (RANS) and Unsteady-RANS simulations are carried out to assess the aerodynamic characteristics of the blade rows. The aeroacoustic modelling consists of simulations with an Euler acoustic solver to compare the modal transmis-1 The presented work was divided equally between the Institute of Turbomachinery and Fluid Dynamics in Hanover and the Mechanical Engineering Department in Sherbrooke

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