Aeroacoustics Your title goes here Methodologies, Validations and - - PowerPoint PPT Presentation

▶

Oct 28, 2023 271 likes •445 views

Aeroacoustics Your title goes here Methodologies, Validations and Continuing Outlook Your subtitle goes here Fred Mendona Some Characteristic Flow Noise Issues Autom omotiv otive e extern ernal, al, sunroof of buffet eting,

SLIDE 1

Your title goes here Your subtitle goes here

Aeroacoustics

Methodologies, Validations and Continuing Outlook Fred Mendonça

SLIDE 2

Some Characteristic Flow Noise Issues

Autom
motiv
tive

e – extern ernal, al, sunroof

f buffet

eting, ing, HVAC

Aerospace – airframe noise, jets, ECS

SLIDE 3

Industry and Expert Collaborations

–

DESTINY Aeroacoustics Projects (2002 - 2005)

–

German Auto manufacturers – Aeroacoustics Working Group (2005-7 and 2009-11)

Daimler, BMW, Audi, VW, Porsche

–

Acoustic partner collaborations

LMS through BEM codes SYSNOISE and V.Lab.Acoustics

FFT’s FEA code, ACTRAN

ESI’s SEA code, VA-One

–

Aero-Vibroacoustics

External flow excitation, internal structural noise transmission

Internal flow excitation, external structural noise transmission

One of the originators in the field, Paul Bremner, expert advisor to CD-adapco

–

LES for Acoustics, Cambridge University Press

http://www.cambridge.org/us/catalogue/catalogue.asp?isbn=0521871441

SLIDE 4

Introduction

– CFD, with the correct physical models…. » Is very capable of simulating the sources of aeroacoustic noise

Directly (LES) for applications in the low Reynolds number range
Indirectly (RANS) using broadband syntesization models

» Also possible to propagate the noise – STAR-CCM+ provides the software tools to extract the maximum

value from the CFD process in Aeroacoustics CAE

» Dedicated Training programme for Aeroacoustics – CD-adapco sees as its responsibility to deliver the validated tools,

with the best-practice advice; stating value and limitations

SLIDE 5

Aeroacoustics Overview: v6.04 and beyond

Ae Aeroacous roacoustics ics Sim Simula lations ions Optio ions ns Steady ady state Transient ansient

Broad

adban

band d Correla rrelatio ions ns Synt nthe hesized ized Fluc uctua uatio ions ns SNGR CURLE surf rfac ace PROUDMAN AN volume lume GOLD LDST STEI EIN 2D-ax axi LEE LEE Lille ley Mesh Freque equenc ncy Cut-off LES LES DES Trans ansien ient RANS Point int and d Surface FFTs Auto

and Cross Spectra

ra – cohere herenc nce e and phas ase FW FW-H Direc ect Export

rt to

ACTRAN AN / V.Lab ab.Ac Acou

ustics

ics / VA-One One Expor port to Propa

pagat

gation ion codes des Direc ect Noise e Propa

paga

gatio ion Direc ect Export

rt to

SEA for r inter ernal nal nois ise e charac haracter eris isatio ion

SLIDE 6

Process

–

Steady-state: Model Optimisation

Source Locations (Broadband correlations, Lilley, Curle, Proudman)

Mesh requirements (Mesh frequency cut-off estimator)

Assess time-step requirements – Transient: Direct Source Capture

Advanced turbulence models

Advanced boundary conditions

Compressible solutions

–

Direct Propagation (in STAR-CCM+)

–

Propagation via coupling to:

SYSNOISE / V.Lab.Acoustics

FFT-ACTRAN

VA-One

–

VibroAcoustics transmission via SEA, FEA

250 Hz 500 Hz 1000 Hz 2000 Hz

SLIDE 7

Steady-state: Broadband correlations for AAC sources

–

Quadrupole-like sources re-synthesized from steady-state RANS result

–

STAR 1st commercial CFD code to introduce Lilley source visualisation (2000)

–

Curle surface noise correlation

–

Proudman volume correlation

–

Locates maximum noise sources quickly

–

Adds value for

Parametric design changes

Locates regions for mesh refinement

Locates regions for data output

SLIDE 8

Steady-state: Broadband correlations - Examples

Surface (Curle) Volume (Proudman)

SLIDE 9

Steady-state: Mesh Frequency Cut-off Estimator

– Unique to STAR – Estimates the resolvable frequency from steady-state results – Informs user of CFD grid suitability early in the process – E.g. Frequency of up to1000Hz in mirror wake example

SLIDE 10

Transient capabilities

–

LES-type turbulence model

DES (options of Spalart-Allmaras, k-ε, k-ωSST)

DES advection scheme blending

Full LES (wall resolved or unresolved)

–

Advanced wall treatment

y+ insensitive

–

Non-reflecting conditions for

Inflow and outflow boundaries

–

Full Compressibility

Interaction between the flow and acoustics

Especially for cavity resonance

–

Most efficient commercial transient solver

2nd order space and time discretisation

–

Spectral Analysis

» FFT at points and surfaces »

Auto and Cross spectra – coherence and phase

Frequency and Wave Number Fourier analysis

SLIDE 11

Validated Methodology

–

Monitor point in mirror wake

–

Tail-off in predicted spectrum at mesh cut-off frequency of ~1000 Hz STAR Experiment

SLIDE 12

Validated Methodology

Surface FFT (dB) at 500Hz (top) and 1000Hz (bottom)

SLIDE 13

Direct Propagation in STAR-CCM+

– Mesh requirement » 20 cells per acoustic wavelength ( λ= c / f )

In ambient conditions, you need cells of ~15mm to propagate a signal at

1000Hz

Domain size = 1000D, (~10 λ )

– Non-reflective in/outflow boundaries

SLIDE 14

100 0 Hz 500 0 Hz 3150 50 Hz Over erall all

Propagation – FW-H and 3rd party code export

–

STAR results capture the acoustic sources for propagation via

Ffowcs Williams-Hawkings (far-field propagation of compact sources without internal reflections)

–

STAR offers coupling to 3rd party propagation codes:

FFT, ACTRAN

LMS, Virtual.Lab.Acoustics

ESI, VA-One

–

VibroAcoustics

Using FVS in STAR-CCM+

Export to SEA and FEA

SLIDE 15

Industrial examples with Validations

–

Resonance Effects

–

Slat / Cavity /Flap

–

HVAC duct: Dipole Sources

–

Fan Noise

–

Side-view mirror: External Aero

–

AIAA Aeroacoustics Benchmarks (2009)

END

SLIDE 16