Application of a hybrid computational aeroacoustics method to an automotive blower

Piellard, Mélanie; Coutty, Bruno

doi:10.1533/9780857095053.6.447

Cited by 3 publications

(3 citation statements)

References 3 publications

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“…To give a reliable assessment of the whistling potentiality, either compressible flow simulation, i.e., Direct Noise Computation (DNC), or a hybrid workflow incorporating forward-and back-coupling from the flow to the acoustic model is required. Due to the disparity of length scales in flow acoustics [8], [9], DNC poses high requirements regarding temporal and spatial resolution of the domain resulting in high computational cost. Similarly, back-coupling from the acoustic to the flow domain adds significant complexity, as flow and acoustic fields need to be solved simultaneously.…”

Section: Introductionmentioning

confidence: 99%

Using eigenmode forcing to investigate flow instability mechanisms causing whistling sound

Wurzinger,

Mayr-Mittermüller,

Kaltenbacher

et al. 2024

Proceedings of the 10th Convention of the European Acoustics Association Forum Acusticum 2023

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In flow acoustical problem sets, there is typically a large disparity of scales between hydrodynamical and acoustical phenomena both in amplitude and spatial extent. This results in major difficulties for low Mach number and high Reynolds number applications, resolving both acoustic and flow fields in a compressible flow simulation and applying correct boundary conditions. Consequently, during the design process of flow guiding structures, flow, and acoustic fields are only investigated separately, or a forward coupled simulation workflow (standard hybrid aeroacoustic approach) is used. This methodology, however, fails to accurately predict any flow instability mechanism caused by back-coupling of the acoustic field to the flow field, as is the case for whistling sound. This work presents a novel approach to excite flow instabilities, such as the whistling mechanism by applying acoustical mode forcing on an otherwise incompressible flow simulation. This allows for optimal domain size and boundary conditions of the incompressible flow domain. Furthermore, in contrast to strong direct coupling of the flow and acoustic domains, all interpolation tasks can be performed a priori. The relatively low computational cost makes this method especially well applicable to the task of designing complex flow-guiding structures such that whistling is mitigated in an early development stage.

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Section: Introductionmentioning

confidence: 99%

Using eigenmode forcing to investigate flow instability mechanisms causing whistling sound

Wurzinger,

Mayr-Mittermüller,

Kaltenbacher

et al. 2024

Proceedings of the 10th Convention of the European Acoustics Association Forum Acusticum 2023

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“…When aeroacoustic effects are involved, the hybrid approach is an efficient way to limit the computational effort and to overcome the challenge of the disparity of scales in CAA [10,11]. The application of this two-step approach to various kinds of flow configurations, such as fans [12,13], jets [14], and other external flows [15][16][17] can be found in literature. Aeroacoustics of internal (ducted) flows with constrictions was numerically [18][19][20][21][22][23][24][25][26][27][28] and experimentally [29][30][31][32] investigated in the past, considering mostly rectangular ducts with symmetric constrictions.…”

Section: Introductionmentioning

confidence: 99%

Aeroacoustic formulations for confined flows based on incompressible flow data

et al. 2022

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The hybrid aeroacoustic approach is an efficient way to address the issue of the disparity of scales in Computational AeroAcoustics (CAA) at low Mach numbers. In the present paper, three wave equations governing propagation of flow-induced sound of low Mach number flows, namely the Perturbed Convective Wave Equation (PCWE), Ribner’s Dilatation (RIB) equation, and Lighthill’s wave equation, are applied using the Finite Element Method (FEM). An airflow through a circular pipe with a half-moon-shaped orifice at three operating flow speeds is considered, where validation data from measurements on a dedicated test rig is available. An extensive analysis of the flow field is provided based on the results of the incompressible flow simulation. The resulting acoustic source terms are investigated, and the relevant source term contributions are determined. The results of the acoustic propagation simulations revealed that the PCWE and RIB are best suited for the present task. The overall deviation of the predicted pressure spectra from the measured mean values amounted to 2.26 and 2.13 times the standard deviation of the measurement compared to 3.55 for Lighthill’s wave equation. Besides reliably predicting the flow-induced sound, the numerical procedure of source term computation is straightforward for PCWE and RIB, where the source term contributions, shown to be relevant, solely consist of time derivatives of the incompressible pressure. In contrast, the Lighthill source term involves spatial derivatives and, thus, is strongly dependent on the spatial resolution and the numerical method actually used for approximating these terms.

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“…This FEAA method has been used for aero 21,22 and hydro 23 flow-induced noise simulations, with some comparisons with experiments also available in the literature. [24][25][26] The approach relies on a variational formulation of Lighthill's acoustic analogy, in which the acoustic analogy equations are discretized by a finite element discretization in Fourier space, which determines the radiated noise up to the free field, as introduced in Piellard and Coutty, 27 and Actran 28 and the instantaneous noise as in Caro et al 29 Meanwhile, the method also solves the acoustic equations while taking into account the spectral volume and surface source. This article is organized as follows.…”

Section: Introductionmentioning

confidence: 99%

Flow-induced noise simulation using detached eddy simulation and the finite element acoustic analogy method

Zhou

et al. 2016

Advances in Mechanical Engineering

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Signals in long-distance pipes are complex due to flow-induced noise generated in special structure, and the computation of these noise sources is difficult and time-consuming. To address this problem, a hybrid method based on computational fluid dynamics and Lighthill's acoustic analogy theory is proposed to simulate flow-induced noise, with the results showing that the method is sufficient for noise predictions. The proposed method computes the turbulent flow field using detached eddy simulation and then calculates turbulence-generated sound using the finite element acoustic analogy method, which solves acoustic sources as volume sources. The velocity field obtained in the detached eddy simulation computation provides the sound source through interpolation between the computational fluid dynamics and acoustic meshes. The hybrid method is validated and assessed by comparing data from the cavity in pipe and large eddy simulation results. The peak value of flow-induced noise calculated at the monitor point is in good agreement with experimental data available in the literature.

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Application of a hybrid computational aeroacoustics method to an automotive blower

Cited by 3 publications

References 3 publications

Using eigenmode forcing to investigate flow instability mechanisms causing whistling sound

Using eigenmode forcing to investigate flow instability mechanisms causing whistling sound

Aeroacoustic formulations for confined flows based on incompressible flow data

Flow-induced noise simulation using detached eddy simulation and the finite element acoustic analogy method

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