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Efficient prediction of broadband trailing edge noise and application to porous edge treatment

Faßmann, Benjamin and Rautmann, Christof and Ewert, Roland and Delfs, Jan Werner (2018) Efficient prediction of broadband trailing edge noise and application to porous edge treatment. Cornell University Library. [Other]

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Official URL: https://arxiv.org/abs/1810.02642

Abstract

Trailing edge noise generated by turbulent flow traveling past an edge of an airfoil is one of the most essential aeroacoustic sound generation mechanisms. It is of great interest for noise problems in various areas of industrial application. First principle based CAA with short response time are needed in the industrial design process for reliable prediction of spectral differences in turbulent-boundary-layer trailing-edge noise due to design modifications. In this paper, an aeroacoustic method is studied, resting on a hybrid CFD/CAA procedure. In a first step RANS simulation provides a time-averaged solution, including the mean-flow and turbulence statistics such as length-scale, time-scale and turbulence kinetic energy. Based on these, fluctuating sound sources are then stochastically generated by the Fast Random Particle-Mesh Method to simulate in a second CAA step broadband aeroacoustic sound. From experimental findings it is well known that porous trailing edges significantly lower trailing edge noise level over a large range of frequencies reaching up to 8dB reduction. Furthermore, sound reduction depends on the porous material parameters, e.g. geometry, porosity, permeability and pore size. The paper presents first results for an extended hybrid CFD/CAA method including porous materials with prescribed parameters. To incorporate the effect of porosity, an extended formulation of the Acoustic Perturbation Equations with source terms is derived based on a reformulation of the volume averaged Navier-Stokes equations into perturbation form. Proper implementation of the Darcy and Forchheimer terms is verified for sound propagation in homogeneous and anisotropic porous medium. Sound generation is studied for a generic symmetric NACA0012 airfoil without lift to separate secondary effects of lift and camber on sound from those of the basic edge noise treatments.

Item URL in elib:https://elib.dlr.de/125460/
Document Type:Other
Title:Efficient prediction of broadband trailing edge noise and application to porous edge treatment
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Faßmann, BenjaminBenjamin.Fassmann (at) dlr.deUNSPECIFIED
Rautmann, ChristofChristof.Rautmann (at) dlr.deUNSPECIFIED
Ewert, RolandRoland.Ewert (at) dlr.deUNSPECIFIED
Delfs, Jan WernerJan.Delfs (at) dlr.deUNSPECIFIED
Date:October 2018
Journal or Publication Title:arXiv 2331-8422
Refereed publication:No
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
DOI :arXiv:1810.02642
Publisher:Cornell University Library
Series Name:Fluid Dynamics (physics.flu-dyn)
ISSN:2331-8422
Status:Published
Keywords:Aeroacoustic; Trailing Edge Noise; Pourous Material; Noise Reduction
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:fixed-wing aircraft
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Simulation and Validation
Location: Braunschweig
Institutes and Institutions:Institute for Aerodynamics and Flow Technology > Technical Acoustics
Deposited By: Faßmann, Benjamin
Deposited On:04 Feb 2019 11:11
Last Modified:04 Feb 2019 11:11

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