Simplified permeable surface correction for frequency-domain Ffowcs Williams and Hawkings integrals

Zhou, Zhiteng; Wang, Hongping; Wang, Shizhao

doi:10.1016/j.taml.2021.100259

Cited by 16 publications

(4 citation statements)

References 13 publications

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“…Nevertheless, future studies will concern sensitivity analysis of the model, taking into account the influence of monopole, dipole and quadrupole sources. Numerical calculation and verification will be preceded by the implementation of, among others, the method proposed in the paper [55].…”

Section: Discussionmentioning

confidence: 99%

Numerical Analysis of Aeroacoustic Phenomena Generated by Truck Platoons

Hamiga

Ciesielka

2021

Sustainability

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In recent years there has been dynamic progress in the development of fully autonomous trucks and their combination and coordination into sets of vehicles moving behind each other within short distances, i.e., platooning. Numerous reports from around the world present significant benefits of platooning for the environment due to reduced emissions, reduced fuel costs, and improved logistics in the transport industry. This paper presents original aerodynamic and aeroacoustic studies of identical truck column models. They are divided into four main stages. In the first, a truck model and three columns of identical trucks with different distances between the vehicles was made and tested using computational fluid dynamics (CFD). Two turbulence models were used in the study: k−ω shear stress transport (SST) and large eddy simulation (LES). The aim of the work was to determine the drag coefficients for each set of vehicles. The second stage of work included determination of sound field distributions generated by moving vehicles. Using the Ffowcs Williams–Hawkings (FW-H) analogy, the sound pressure levels were determined, followed by the sound pressure levels A. In order to verify the correctness of the work carried out, field tests were also performed and additional acoustic calculations were carried out using the NMPB-Routes-2008 and ISO 9613-2 models. Calculations were performed using SoundPlan software. The performed tests showed good quality of the built aerodynamic and aeroacoustic models. The results presented in this paper have a universal character and can be used to build intelligent transport systems (ITSs) and intelligent environmental management systems (IEMSs) for municipalities, counties, cities, and urban agglomerations by taking into account the platooning process.

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Section: Discussionmentioning

confidence: 99%

Numerical Analysis of Aeroacoustic Phenomena Generated by Truck Platoons

Hamiga

Ciesielka

2021

Sustainability

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“…where y 0 is required to be on the integral boundary. For 2D flows, the far-field asymptotic of Green's function is [24] G(x; y) = i 4…”

Section: Mass Conserved Formulationmentioning

confidence: 99%

“…To clarify the mass-conserved monopole term I Tmc (x, ω), we expand the monopole term (Equation ( 3)) as follows, using the higher-order derivatives of Green's function, as proposed by zhou et al [20,24].…”

Section: Mass Conserved Formulationmentioning

confidence: 99%

Mass-Conserved Solution to the Ffowcs-Williams and Hawkings Equation for Compact Source Regions

et al. 2023

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A mass-conserved formulation for the Ffowcs-Williams–Hawkings (FW–H) integral is proposed to suppress contributions of spurious mass flux to the far-field sound at very low Mach numbers. The far-field condition and compact-source region assumptions are employed. By using higher-order derivatives of Green’s function, an expansion of the integrand in the monopole term is performed. This expansion transforms the mass-flux like monopole term into a series including different orders of velocity moment. At very low Mach numbers, the zero-order term is exactly the contribution from the spurious mass flux. The proposed mass-conserved formulation is confirmed by using an unsteady dipole, a two-dimensional (2D) incompressible convecting vortex, a circular-cylinder flow, and a co-rotating vortex pair. Additional spurious mass flux is added to the unsteady dipole, 2D incompressible convecting vortex, and flows over a circular cylinder; and the spurious mass flux of the co-rotating vortex pair comes from the residual of an incompressible-flow simulation. The far-field sound is found to be sensitive to spurious mass flux in the unsteady dipole and 2D incompressible convecting vortex cases. Then, the computation of the monopole-term expansion with the flow over a circular cylinder is presented. Fast convergence performance was observed, suggesting that the expansion requires little extra computational resources. Finally, FW–H boundary dependence is observed in the co-rotating vortex-pair case and eliminated by using the proposed mass-conserved formulation.

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“…This decoupling potentially enables the direct verification of the theoretical analysis presented by Ianniello & De Bernardis (2015) and Ianniello (2016). In addition, the porous formulation is typically affected by the issue of the spurious sound due to the eddies crossing the permeable surface of integration, although the recent works by Zhou, Wang & Wang (2021 a ) and Zhou et al. (2021 b , 2022) proposed a fix to this problem.…”

Section: Introductionmentioning

confidence: 99%

Hydroacoustic analysis of a marine propeller using large-eddy simulation and acoustic analogy

et al. 2022

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The acoustic analogy is adopted to characterise the signature of a seven-bladed submarine propeller, relying on a high-fidelity large-eddy simulation, performed on a computational grid consisting of 840 million points. Results demonstrate that the nonlinear terms of the Ffowcs-Williams and Hawkings equation quickly become dominant moving away from the propeller along the direction of its wake development. While the linear terms experience a decay moving downstream, the nonlinear terms grow in the near wake, as a result of the development of wake instability. In particular, this growth affects frequencies lower than the blade frequency. Therefore, the acoustic signature of the propeller is mainly tonal in the near field only, due to the thickness and loading components of noise from the surface of the propeller and the periodic perturbation caused by its tip vortices. They develop instability at a faster rate, compared with the hub vortex, triggering the process of energy cascade towards higher frequencies and contributing in this way to broadband noise.

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Simplified permeable surface correction for frequency-domain Ffowcs Williams and Hawkings integrals

Cited by 16 publications

References 13 publications

Numerical Analysis of Aeroacoustic Phenomena Generated by Truck Platoons

Numerical Analysis of Aeroacoustic Phenomena Generated by Truck Platoons

Mass-Conserved Solution to the Ffowcs-Williams and Hawkings Equation for Compact Source Regions

Hydroacoustic analysis of a marine propeller using large-eddy simulation and acoustic analogy

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